Real stats on engine failures? [Archive]

slomo

November 24th 03, 10:42 PM

I have about 3000 hrs over 45 years.
Three failures which I had no contribution to (I did not precipitate the
failure).
One total power loss - carburetor malfunction - landed off airport.
One partial power loss - turbo charger induction failure
One damn near total power loss on takeoff - turbo charger failure

I've had others, but they were due to "unusual circumstances".

One complete failure of a magneto. Didn't count that as an engine failure,
but the reduction in power is sure noticeable at night.

Just to put some perspective on the equipment. Two out of the three
were in airplanes less than a year old.

In article >,
(Captain Wubba) wrote:
>Howdy. I was discussing with a friend of mine my concerns about flying
>single-engine planes at night or in hard IFR, due to the possibility
>of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
>3500 hours, and been around airplanes for a long time, so I tend to
>give credence to his experiences. He asked me how often I thought a
>piston engine had an in-flight engine failure. I guestimated once
>every 10,000 hours or so. He said that was *dramatically*
>over-estimating the failure rate. He said that in his experience it is
>at least 40,000 to 50,000 hours per in-flight engine failure. The
>place where he works sometimes as a mechanic has plenty of planes come
>in for overhauls and annuals, and he estimates that for every plane
>that has had an engine failure before TBO, at least 20-30 make it to
>TBO without any failure (which would extrapolate to a similar figure).
>The flight school he teaches at has 7 Cessnas used for primary
>training and rental that have flown at least 40,000 hours total in the
>six years he has been there, and they have not experienced a single
>engine failure.
>
>I emailed Lycoming, and (unsurprisingly) they told me they did not
>keep records about engine failure rates.
>
>So I'd like to find out if anyone has done any objective analysis of
>certificated, piston-engine failure rates in light airplanes. I have
>seen all kinds of 'guesses', but little in the way of objective facts.
>After analyzing NTSB accident data and comparing to annual GA
>flight-hours, I'm starting to think my friend is on the right track,
>but that is a relatively small sample, and has some methodologial
>flaws. It's funny. I know 20,000 hour CFIs who have never had an
>engine failure, and I also know 300 hour PP-ASELs who have had engine
>failures.
>
>Just for giggles, I asked 8 pilot friends/relatives if they had ever
>had an engine failure. The only 'yes' was a relative who lost an
>engine after takeoff on his first solo cross-country in 1958. And I
>know one other pilot who had an engine failure, who I wasn't able to
>talk to.
>
>So what is it? If the engine-failure rate is one failure for every
>50,000 flight hours, I'll feel much less reticent about night/IFR
>single-engine flying than if it is one in 10,000 hours. Anybody have
>any facts or hard data, or have any idea where I might be able to
>track some down?
>
>Thanks,
>
>Cap

Bob Gardner

November 24th 03, 10:54 PM

In 7000 hours I had one engine "failure," which was just a loose hose
between the turbocharger and intake manifold. Engine didn't really fail, it
just lost boost on that side. I've had some engine anomalies, but nothing
that would meet the definition of failure. I would tend to agree that
honest-to-goodness failures are very rare when considered in the context of
total operating hours for all powered aircraft.

Bob Gardner

"Captain Wubba" > wrote in message
om...
> Howdy. I was discussing with a friend of mine my concerns about flying
> single-engine planes at night or in hard IFR, due to the possibility
> of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> 3500 hours, and been around airplanes for a long time, so I tend to
> give credence to his experiences. He asked me how often I thought a
> piston engine had an in-flight engine failure. I guestimated once
> every 10,000 hours or so. He said that was *dramatically*
> over-estimating the failure rate. He said that in his experience it is
> at least 40,000 to 50,000 hours per in-flight engine failure. The
> place where he works sometimes as a mechanic has plenty of planes come
> in for overhauls and annuals, and he estimates that for every plane
> that has had an engine failure before TBO, at least 20-30 make it to
> TBO without any failure (which would extrapolate to a similar figure).
> The flight school he teaches at has 7 Cessnas used for primary
> training and rental that have flown at least 40,000 hours total in the
> six years he has been there, and they have not experienced a single
> engine failure.
>
> I emailed Lycoming, and (unsurprisingly) they told me they did not
> keep records about engine failure rates.
>
> So I'd like to find out if anyone has done any objective analysis of
> certificated, piston-engine failure rates in light airplanes. I have
> seen all kinds of 'guesses', but little in the way of objective facts.
> After analyzing NTSB accident data and comparing to annual GA
> flight-hours, I'm starting to think my friend is on the right track,
> but that is a relatively small sample, and has some methodologial
> flaws. It's funny. I know 20,000 hour CFIs who have never had an
> engine failure, and I also know 300 hour PP-ASELs who have had engine
> failures.
>
> Just for giggles, I asked 8 pilot friends/relatives if they had ever
> had an engine failure. The only 'yes' was a relative who lost an
> engine after takeoff on his first solo cross-country in 1958. And I
> know one other pilot who had an engine failure, who I wasn't able to
> talk to.
>
> So what is it? If the engine-failure rate is one failure for every
> 50,000 flight hours, I'll feel much less reticent about night/IFR
> single-engine flying than if it is one in 10,000 hours. Anybody have
> any facts or hard data, or have any idea where I might be able to
> track some down?
>
> Thanks,
>
> Cap

studentpilot

November 24th 03, 11:31 PM

Know a bloke well with over 15'000 hours, he has had no engine failures.
He has had however 4 self inficted engine failures, these were fuel
system failures. Mostly failure to put enough in, failure to check
for water contamination properly, failure to know the aircraft fuel
system. This blokes expirence is all single engine, going from little
Lyc's to Radial's and turbine.

Most Iv'e come across in the last 25 years aviating have had no
problems, usually if there are it's a maintaince issue or operator
induced.

--
studentpilot
------------------------------------------------------------------------
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Michael

November 24th 03, 11:58 PM

(Captain Wubba) wrote
> Howdy. I was discussing with a friend of mine my concerns about flying
> single-engine planes at night or in hard IFR, due to the possibility
> of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> 3500 hours, and been around airplanes for a long time, so I tend to
> give credence to his experiences. He asked me how often I thought a
> piston engine had an in-flight engine failure. I guestimated once
> every 10,000 hours or so. He said that was *dramatically*
> over-estimating the failure rate. He said that in his experience it is
> at least 40,000 to 50,000 hours per in-flight engine failure.

The only vaguely official number that I've ever seen came from a UK
accident report for a US-built twin. The UK investigators queried the
FAA on engine failure rates for the relevant engine, and the only
answer they got was that piston engines have failure rates on the
order of 1 in 1000 to 1 in 10000 hours. This is consistent with my
experience. I've had one non-fuel-related engine failure (partial,
but engine could only produce 20-30% power) in 1600+ hrs. Most people
I know with over 1500 GA hours have had an engine failure.

50,000 hours is not realistic. Excluding a few airline pilots (who
have ALL had engine failures) all my pilot friends together don't have
50,000 hours, and quite a few of them have had engine failures.

I've heard the maintenance shop thing before, but you need to realize
that most engine failures do not result in a major overhaul. Stuck
valves and cracked jugs mean that only a single jug is replaced;
failure of the carb or fuel injection system (my problem) affects only
that component. And oil loss will often seize an engine and make it
not worth overhauling.

There are no real stats on engine failures because engine
manufacturers and the FAA don't want those stats to exist. The FAA
could create those stats simply by requiring pilots to report engine
failures for other than fuel exhaustion/contamination reasons, but
will not.

The truth is, FAA certification requirements have frozen aircraft
piston engines in the past, and now they're less reliable than
automotive engines (not to mention ridiculously expensive).

Michael

Mike O'Malley

November 25th 03, 12:05 AM

"Captain Wubba" > wrote in message
om...
> Howdy. I was discussing with a friend of mine my concerns about flying
> single-engine planes at night or in hard IFR, due to the possibility
> of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> 3500 hours, and been around airplanes for a long time, so I tend to
> give credence to his experiences. He asked me how often I thought a
> piston engine had an in-flight engine failure. I guestimated once
> every 10,000 hours or so. He said that was *dramatically*
> over-estimating the failure rate. He said that in his experience it is

I would say the failure rate is not uniform, and would depend a lot on how the
aircraft are maintained and utilized. Ex: the large univesity flight school I
went to that flies on the order of 10,000 hours a year, has had no engine
failures in the past 10 years that weren't due to pilot error.

However, the company I towed banners for had two complete engine failures and
two partial power failures in the two 3 month seasons I worked for them. In my
1100 hours, I've had one quit on takeoff when a mag that was improperly torqued
down slipped and put the ignition way out of time, and one partial power loss
when a leaky oil control ring finally let go and fouled out one cylinder.

And be careful using NTSB data for your analysis, as not all engine failures are
cause for a report; both of mine ended with me making it home and no bent metal,
so they aren't in the database.

--
Mike

Ben Dover

November 25th 03, 12:33 AM

"Mike O'Malley" > wrote in message
...
> "Captain Wubba" > wrote in message
> om...
> > Howdy. I was discussing with a friend of mine my concerns about flying
> > single-engine planes at night or in hard IFR, due to the possibility
> > of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> > 3500 hours, and been around airplanes for a long time, so I tend to
> > give credence to his experiences. He asked me how often I thought a
> > piston engine had an in-flight engine failure. I guestimated once
> > every 10,000 hours or so. He said that was *dramatically*
> > over-estimating the failure rate. He said that in his experience it is
>
> I would say the failure rate is not uniform, and would depend a lot on how
the
> aircraft are maintained and utilized. Ex: the large univesity flight
school I
> went to that flies on the order of 10,000 hours a year, has had no engine
> failures in the past 10 years that weren't due to pilot error.
>
> However, the company I towed banners for had two complete engine failures
and
> two partial power failures in the two 3 month seasons I worked for them.
In my
> 1100 hours, I've had one quit on takeoff when a mag that was improperly
torqued
> down slipped and put the ignition way out of time, and one partial power
loss
> when a leaky oil control ring finally let go and fouled out one cylinder.
>
> And be careful using NTSB data for your analysis, as not all engine
failures are
> cause for a report; both of mine ended with me making it home and no bent
metal,
> so they aren't in the database.

I had an engine failure (sort of on landing) when a plug failed. I noticed
it after landing at Everglades City. I put on some power to turn and
backtrack and boy did the engine run rough.

I then spent a couple of hours speculating about what would have been the
result if I had screwed up the final approach and had to go around again.
The engine did not like full power. My home base runways are small than
Everglades City so it was not too bad.

Mike Rapoport

November 25th 03, 02:43 AM

I don't have any personally but I have a friend that has had three in
3500hrs. One connecting rod failure in a 210. A crankshaft failure in an
Azetec and I forget the details of the third failure. It has been estimated
that 10% of Malibus have had inflight engine failures of some kind.

Mike
MU-2

"Captain Wubba" > wrote in message
om...
> Howdy. I was discussing with a friend of mine my concerns about flying
> single-engine planes at night or in hard IFR, due to the possibility
> of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> 3500 hours, and been around airplanes for a long time, so I tend to
> give credence to his experiences. He asked me how often I thought a
> piston engine had an in-flight engine failure. I guestimated once
> every 10,000 hours or so. He said that was *dramatically*
> over-estimating the failure rate. He said that in his experience it is
> at least 40,000 to 50,000 hours per in-flight engine failure. The
> place where he works sometimes as a mechanic has plenty of planes come
> in for overhauls and annuals, and he estimates that for every plane
> that has had an engine failure before TBO, at least 20-30 make it to
> TBO without any failure (which would extrapolate to a similar figure).
> The flight school he teaches at has 7 Cessnas used for primary
> training and rental that have flown at least 40,000 hours total in the
> six years he has been there, and they have not experienced a single
> engine failure.
>
> I emailed Lycoming, and (unsurprisingly) they told me they did not
> keep records about engine failure rates.
>
> So I'd like to find out if anyone has done any objective analysis of
> certificated, piston-engine failure rates in light airplanes. I have
> seen all kinds of 'guesses', but little in the way of objective facts.
> After analyzing NTSB accident data and comparing to annual GA
> flight-hours, I'm starting to think my friend is on the right track,
> but that is a relatively small sample, and has some methodologial
> flaws. It's funny. I know 20,000 hour CFIs who have never had an
> engine failure, and I also know 300 hour PP-ASELs who have had engine
> failures.
>
> Just for giggles, I asked 8 pilot friends/relatives if they had ever
> had an engine failure. The only 'yes' was a relative who lost an
> engine after takeoff on his first solo cross-country in 1958. And I
> know one other pilot who had an engine failure, who I wasn't able to
> talk to.
>
> So what is it? If the engine-failure rate is one failure for every
> 50,000 flight hours, I'll feel much less reticent about night/IFR
> single-engine flying than if it is one in 10,000 hours. Anybody have
> any facts or hard data, or have any idea where I might be able to
> track some down?
>
> Thanks,
>
> Cap

John Gaquin

November 25th 03, 03:22 AM

"Captain Wubba" > wrote in message
>
> Anybody have
> any facts or hard data,

No hard data, just a fact. Flying since '72, including 18 years of airline
flying, and I've never had a catastrophic failure of any kind, ever. Just
lucky, I guess.

JG

Richard Hertz

November 25th 03, 03:35 AM

<snip>

> There are no real stats on engine failures because engine
> manufacturers and the FAA don't want those stats to exist. The FAA
> could create those stats simply by requiring pilots to report engine
> failures for other than fuel exhaustion/contamination reasons, but
> will not.
>
> Michael

Even if the FAA did require reporting those failures, without also requiring
pilots/annuals to report to the FAA all the total accumulated hours, the
failure numbers would be useless. (However, I am not an A&P and do not know
if these numbers are reported - I doubt it)

Captain Wubba

November 25th 03, 04:35 AM

Indeed. Interesting. But I'd still like to see some hard data. This is
the kind of problem I run into...most of your pilot friends report
that they have had a failure, but the majority of mine report none.
And none of the 2000+ hour CFI types I asked (I asked 4 of them) have
ever experienced an engine failure. My dad was a pilot with well over
12,000 hours and never had one. Another relative had fewer than 500
hours total in his flying carrer and lost one on his first solo XC.

I asked another A&P I ran into at the airport tonight, and he said he
thought it should be at least 40,000 hours per in-flight engine
failure, but really wasn't sure. Since a big part of flying is risk
management, it would be very helpful to *really* know the risks
involved. If the odds of losing an engine are 1 in 50,000 hours, then
night/hard-IFR single-engine flying becomes a great deal more
appealing than if it is 1 in 10,000 hours.

I'll try to go over the NTSB data more thoroughly, I think a
reasonable extrapolation would be that at least 1 in 4 in-flight
engine failures (probably more) would end up in the NTSB database.
But the cursory review I made earlier made me think the numbers were
much less negative than I had considered before. And the opinions of
these A&Ps are very interesting, because while failure might not
require a total overhaul, it will require *something* to be done by a
mechanic...and if these guys are seeing 30-40 engines make it to TBO
for every one needing repair due to an in-flight failure, that might
well support the 40,000 to 50,000 hour hypothesis.

Cheers,

Cap

(Michael) wrote in message >...
> (Captain Wubba) wrote
> > Howdy. I was discussing with a friend of mine my concerns about flying
> > single-engine planes at night or in hard IFR, due to the possibility
> > of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> > 3500 hours, and been around airplanes for a long time, so I tend to
> > give credence to his experiences. He asked me how often I thought a
> > piston engine had an in-flight engine failure. I guestimated once
> > every 10,000 hours or so. He said that was *dramatically*
> > over-estimating the failure rate. He said that in his experience it is
> > at least 40,000 to 50,000 hours per in-flight engine failure.
>
> The only vaguely official number that I've ever seen came from a UK
> accident report for a US-built twin. The UK investigators queried the
> FAA on engine failure rates for the relevant engine, and the only
> answer they got was that piston engines have failure rates on the
> order of 1 in 1000 to 1 in 10000 hours. This is consistent with my
> experience. I've had one non-fuel-related engine failure (partial,
> but engine could only produce 20-30% power) in 1600+ hrs. Most people
> I know with over 1500 GA hours have had an engine failure.
>
> 50,000 hours is not realistic. Excluding a few airline pilots (who
> have ALL had engine failures) all my pilot friends together don't have
> 50,000 hours, and quite a few of them have had engine failures.
>
> I've heard the maintenance shop thing before, but you need to realize
> that most engine failures do not result in a major overhaul. Stuck
> valves and cracked jugs mean that only a single jug is replaced;
> failure of the carb or fuel injection system (my problem) affects only
> that component. And oil loss will often seize an engine and make it
> not worth overhauling.
>
> There are no real stats on engine failures because engine
> manufacturers and the FAA don't want those stats to exist. The FAA
> could create those stats simply by requiring pilots to report engine
> failures for other than fuel exhaustion/contamination reasons, but
> will not.
>
> The truth is, FAA certification requirements have frozen aircraft
> piston engines in the past, and now they're less reliable than
> automotive engines (not to mention ridiculously expensive).
>
> Michael

Ditch

November 25th 03, 05:43 AM

>No hard data, just a fact. Flying since '72, including 18 years of airline
>flying, and I've never had a catastrophic failure of any kind, ever. Just
>lucky, I guess.

I have just over 5000 hours and have had
4 complete failures, one partial power failure, and 2 precautionary shutdowns.
I've also had a dual prop governor failure in a Twin Otter which lead to
shutting down one of the engines.

It makes me really happy that I did my initial training in gliders!!

-John
*You are nothing until you have flown a Douglas, Lockheed, Grumman or North
American*

R. Hubbell

November 25th 03, 07:20 AM

On 24 Nov 2003 11:31:57 -0800
(Captain Wubba) wrote:

> Howdy. I was discussing with a friend of mine my concerns about flying
> single-engine planes at night or in hard IFR, due to the possibility
> of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> 3500 hours, and been around airplanes for a long time, so I tend to
> give credence to his experiences. He asked me how often I thought a
> piston engine had an in-flight engine failure. I guestimated once
> every 10,000 hours or so. He said that was *dramatically*
> over-estimating the failure rate. He said that in his experience it is
> at least 40,000 to 50,000 hours per in-flight engine failure. The
> place where he works sometimes as a mechanic has plenty of planes come
> in for overhauls and annuals, and he estimates that for every plane
> that has had an engine failure before TBO, at least 20-30 make it to
> TBO without any failure (which would extrapolate to a similar figure).
> The flight school he teaches at has 7 Cessnas used for primary
> training and rental that have flown at least 40,000 hours total in the
> six years he has been there, and they have not experienced a single
> engine failure.
>
> I emailed Lycoming, and (unsurprisingly) they told me they did not
> keep records about engine failure rates.
>
> So I'd like to find out if anyone has done any objective analysis of
> certificated, piston-engine failure rates in light airplanes. I have
> seen all kinds of 'guesses', but little in the way of objective facts.
> After analyzing NTSB accident data and comparing to annual GA
> flight-hours, I'm starting to think my friend is on the right track,
> but that is a relatively small sample, and has some methodologial
> flaws. It's funny. I know 20,000 hour CFIs who have never had an
> engine failure, and I also know 300 hour PP-ASELs who have had engine
> failures.
>
> Just for giggles, I asked 8 pilot friends/relatives if they had ever
> had an engine failure. The only 'yes' was a relative who lost an
> engine after takeoff on his first solo cross-country in 1958. And I
> know one other pilot who had an engine failure, who I wasn't able to
> talk to.
>
> So what is it? If the engine-failure rate is one failure for every
> 50,000 flight hours, I'll feel much less reticent about night/IFR
> single-engine flying than if it is one in 10,000 hours. Anybody have
> any facts or hard data, or have any idea where I might be able to
> track some down?
>
> Thanks,
>
> Cap

I think it's a reasonable question to ask bnut to me it's more important to
know how many engine failures resulted in fatalities since if the engine
failed and they walked away from it then who the hell cares what failed
as long as you live to fly again. Am I making any sense? The stat I'm
tinking of would be engine failures where a fatality resulted and that
number will be many more hours than just a engine failure and that's
the number that I'll live close to if I have to live close to some fear
factor. Even if I'm carried away on a stretcher it beats paying the
down mortgage. The engine will just be the last thing I'd think of.

Do you know what that does to your numbers when you include fatals?

R. Hubbell

Andrew Rowley

November 25th 03, 10:41 AM

studentpilot > wrote:

>Know a bloke well with over 15'000 hours, he has had no engine failures.
>He has had however 4 self inficted engine failures, these were fuel
>system failures. Mostly failure to put enough in, failure to check
>for water contamination properly, failure to know the aircraft fuel
>system. This blokes expirence is all single engine, going from little
>Lyc's to Radial's and turbine.

Why do you exclude fuel exhaustion, fuel contamination etc? Don't they
happen if you're IFR?

If you're IFR or at night it doesn't really matter WHY it stops.

Morgans

November 25th 03, 10:45 AM

"R. Hubbell" > wrote > > Cap
>
>
> I think it's a reasonable question to ask bnut to me it's more important
to
> know how many engine failures resulted in fatalities since if the engine
> failed and they walked away from it then who the hell cares what failed
> as long as you live to fly again. Am I making any sense? The stat I'm
> tinking of would be engine failures where a fatality resulted and that
> number will be many more hours than just a engine failure and that's
> the number that I'll live close to if I have to live close to some fear
> factor. Even if I'm carried away on a stretcher it beats paying the
> down mortgage. The engine will just be the last thing I'd think of.
>
> Do you know what that does to your numbers when you include fatals?
>
>
> R. Hubbell
>
>
That is ridiculous! What happens after the engine failure is a combination
of timing, luck, location, with a mix of judgment and skill. That is what
prevents fatalities.

Saying what you said, is like saying a fart is only a fart, if it results in
a ****.

Get a grip!
--
Jim in NC

John Gaquin

November 25th 03, 01:04 PM

Well, I've had a couple of precautionary shutdowns in a commuter t-prop,
both ultimately traced to faulty sensor or indicator; and a couple of
failed generators or hydraulic systems, etc, but these last occurred in
Boeing transports with multiple redundancy. I've never encountered a
failure that was a show-stopper. Knock wood.

JG

"Ditch" > wrote in message
>
> I have just over 5000 hours and have had
> 4 complete failures, one partial power failure, and 2 precautionary
shutdowns.
> I've also had a dual prop governor failure in a Twin Otter which lead to
> shutting down one of the engines.

November 25th 03, 01:31 PM

Night VFR engine failure:

1. turn on landing lights,

2. if you don't like what you see, turn them back off!

Hope this helps,
Peter

Captain Wubba

November 25th 03, 01:49 PM

Andrew Rowley > wrote in message >...
> studentpilot > wrote:
>
> >Know a bloke well with over 15'000 hours, he has had no engine failures.
> >He has had however 4 self inficted engine failures, these were fuel
> >system failures. Mostly failure to put enough in, failure to check
> >for water contamination properly, failure to know the aircraft fuel
> >system. This blokes expirence is all single engine, going from little
> >Lyc's to Radial's and turbine.
>
> Why do you exclude fuel exhaustion, fuel contamination etc? Don't they
> happen if you're IFR?
>
> If you're IFR or at night it doesn't really matter WHY it stops.

Because I can control these problems. If I do a proper preflight, the
probability of fuel contamination is very, very low. If I do the
proper fuel calculations and check the fuel levels and carry proper
reserves, I'm not going to run out of gas.

This is about risk management. I can manage the risks of fuel
contamination or exhaustion very easily, if I exercise diligence and
care. If those are no longer concerns, the primary engine-related
concern becomes mechanical failure, and that's what I'm looking at.

Cap

Captain Wubba

November 25th 03, 01:56 PM

"R. Hubbell" > wrote in message news:<%oDwb.3381$ZE1.73@fed1read04>...
> On 24 Nov 2003 11:31:57 -0800
> (Captain Wubba) wrote:
>
> > Howdy. I was discussing with a friend of mine my concerns about flying
> > single-engine planes at night or in hard IFR, due to the possibility
> > of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> > 3500 hours, and been around airplanes for a long time, so I tend to
> > give credence to his experiences. He asked me how often I thought a
> > piston engine had an in-flight engine failure. I guestimated once
> > every 10,000 hours or so. He said that was *dramatically*
> > over-estimating the failure rate. He said that in his experience it is
> > at least 40,000 to 50,000 hours per in-flight engine failure. The
> > place where he works sometimes as a mechanic has plenty of planes come
> > in for overhauls and annuals, and he estimates that for every plane
> > that has had an engine failure before TBO, at least 20-30 make it to
> > TBO without any failure (which would extrapolate to a similar figure).
> > The flight school he teaches at has 7 Cessnas used for primary
> > training and rental that have flown at least 40,000 hours total in the
> > six years he has been there, and they have not experienced a single
> > engine failure.
> >
> > I emailed Lycoming, and (unsurprisingly) they told me they did not
> > keep records about engine failure rates.
> >
> > So I'd like to find out if anyone has done any objective analysis of
> > certificated, piston-engine failure rates in light airplanes. I have
> > seen all kinds of 'guesses', but little in the way of objective facts.
> > After analyzing NTSB accident data and comparing to annual GA
> > flight-hours, I'm starting to think my friend is on the right track,
> > but that is a relatively small sample, and has some methodologial
> > flaws. It's funny. I know 20,000 hour CFIs who have never had an
> > engine failure, and I also know 300 hour PP-ASELs who have had engine
> > failures.
> >
> > Just for giggles, I asked 8 pilot friends/relatives if they had ever
> > had an engine failure. The only 'yes' was a relative who lost an
> > engine after takeoff on his first solo cross-country in 1958. And I
> > know one other pilot who had an engine failure, who I wasn't able to
> > talk to.
> >
> > So what is it? If the engine-failure rate is one failure for every
> > 50,000 flight hours, I'll feel much less reticent about night/IFR
> > single-engine flying than if it is one in 10,000 hours. Anybody have
> > any facts or hard data, or have any idea where I might be able to
> > track some down?
> >
> > Thanks,
> >
> > Cap
>
>
> I think it's a reasonable question to ask bnut to me it's more important to
> know how many engine failures resulted in fatalities since if the engine
> failed and they walked away from it then who the hell cares what failed
> as long as you live to fly again. Am I making any sense? The stat I'm
> tinking of would be engine failures where a fatality resulted and that
> number will be many more hours than just a engine failure and that's
> the number that I'll live close to if I have to live close to some fear
> factor. Even if I'm carried away on a stretcher it beats paying the
> down mortgage. The engine will just be the last thing I'd think of.
>
> Do you know what that does to your numbers when you include fatals?
>
>
> R. Hubbell

Actually I'd really like to know that too. When I delve more deeply
into the NTSB stuff, I'll break out fatalities. And it does
relate....I am most concerned with IFR and night flying, with this
specific question. An engine loss at altitude in day VFR should almost
never be fatal; it probably shouldn't even bend the plane very often.
But at night or in hard IFR I'd expect the fatality rate to be rather
high. What it is exactly will be interesting to find out. Certainly it
is easier to find out fatalities than it is total engine failures. If
I can glean these numbers from the NTSB database, I'll let you know.
Since this is mostly aboiut risk management, it will be interesting to
really know the risks *after* the engine failure as well.

Cheers,

Cap

Mike Rapoport

November 25th 03, 02:40 PM

No you are not making much sense. If you live and fly in the Midwest then
the chances of survival after an engine failure are very different than
flying over rough terrain.

Mike
MU-2

"R. Hubbell" > wrote in message
news:%oDwb.3381$ZE1.73@fed1read04...
> On 24 Nov 2003 11:31:57 -0800
> (Captain Wubba) wrote:
>
> > Howdy. I was discussing with a friend of mine my concerns about flying
> > single-engine planes at night or in hard IFR, due to the possibility
> > of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> > 3500 hours, and been around airplanes for a long time, so I tend to
> > give credence to his experiences. He asked me how often I thought a
> > piston engine had an in-flight engine failure. I guestimated once
> > every 10,000 hours or so. He said that was *dramatically*
> > over-estimating the failure rate. He said that in his experience it is
> > at least 40,000 to 50,000 hours per in-flight engine failure. The
> > place where he works sometimes as a mechanic has plenty of planes come
> > in for overhauls and annuals, and he estimates that for every plane
> > that has had an engine failure before TBO, at least 20-30 make it to
> > TBO without any failure (which would extrapolate to a similar figure).
> > The flight school he teaches at has 7 Cessnas used for primary
> > training and rental that have flown at least 40,000 hours total in the
> > six years he has been there, and they have not experienced a single
> > engine failure.
> >
> > I emailed Lycoming, and (unsurprisingly) they told me they did not
> > keep records about engine failure rates.
> >
> > So I'd like to find out if anyone has done any objective analysis of
> > certificated, piston-engine failure rates in light airplanes. I have
> > seen all kinds of 'guesses', but little in the way of objective facts.
> > After analyzing NTSB accident data and comparing to annual GA
> > flight-hours, I'm starting to think my friend is on the right track,
> > but that is a relatively small sample, and has some methodologial
> > flaws. It's funny. I know 20,000 hour CFIs who have never had an
> > engine failure, and I also know 300 hour PP-ASELs who have had engine
> > failures.
> >
> > Just for giggles, I asked 8 pilot friends/relatives if they had ever
> > had an engine failure. The only 'yes' was a relative who lost an
> > engine after takeoff on his first solo cross-country in 1958. And I
> > know one other pilot who had an engine failure, who I wasn't able to
> > talk to.
> >
> > So what is it? If the engine-failure rate is one failure for every
> > 50,000 flight hours, I'll feel much less reticent about night/IFR
> > single-engine flying than if it is one in 10,000 hours. Anybody have
> > any facts or hard data, or have any idea where I might be able to
> > track some down?
> >
> > Thanks,
> >
> > Cap
>
>
> I think it's a reasonable question to ask bnut to me it's more important
to
> know how many engine failures resulted in fatalities since if the engine
> failed and they walked away from it then who the hell cares what failed
> as long as you live to fly again. Am I making any sense? The stat I'm
> tinking of would be engine failures where a fatality resulted and that
> number will be many more hours than just a engine failure and that's
> the number that I'll live close to if I have to live close to some fear
> factor. Even if I'm carried away on a stretcher it beats paying the
> down mortgage. The engine will just be the last thing I'd think of.
>
> Do you know what that does to your numbers when you include fatals?
>
>
> R. Hubbell
>
>
>

Mike Rapoport

November 25th 03, 02:42 PM

Presumably all the pilots who had engine failures believed the same thing.

Mike
MU-2

"Captain Wubba" > wrote in message
om...
> Andrew Rowley > wrote in message
>...
> > studentpilot > wrote:
> >
> > >Know a bloke well with over 15'000 hours, he has had no engine
failures.
> > >He has had however 4 self inficted engine failures, these were fuel
> > >system failures. Mostly failure to put enough in, failure to check
> > >for water contamination properly, failure to know the aircraft fuel
> > >system. This blokes expirence is all single engine, going from little
> > >Lyc's to Radial's and turbine.
> >
> > Why do you exclude fuel exhaustion, fuel contamination etc? Don't they
> > happen if you're IFR?
> >
> > If you're IFR or at night it doesn't really matter WHY it stops.
>
> Because I can control these problems. If I do a proper preflight, the
> probability of fuel contamination is very, very low. If I do the
> proper fuel calculations and check the fuel levels and carry proper
> reserves, I'm not going to run out of gas.
>
> This is about risk management. I can manage the risks of fuel
> contamination or exhaustion very easily, if I exercise diligence and
> care. If those are no longer concerns, the primary engine-related
> concern becomes mechanical failure, and that's what I'm looking at.
>
>
> Cap

Michael

November 25th 03, 02:51 PM

(Captain Wubba) wrote
> Indeed. Interesting. But I'd still like to see some hard data.

Me too.

> Since a big part of flying is risk
> management, it would be very helpful to *really* know the risks
> involved. If the odds of losing an engine are 1 in 50,000 hours, then
> night/hard-IFR single-engine flying becomes a great deal more
> appealing than if it is 1 in 10,000 hours.

And what if it's 1 in 1000 hours? Then night/hard-IFR single-engine
flying becomes foolhardy.

> I'll try to go over the NTSB data more thoroughly, I think a
> reasonable extrapolation would be that at least 1 in 4 in-flight
> engine failures (probably more) would end up in the NTSB database.

That doesn't seem at all consistent with my experience. Of all my
acquaintances who have had engine failures, only one wound up in the
NTSB database because he died and took his passengers with him. One
severely damaged the airplane but walked away and contrary to
regulation never reported it. The plane was eventually rebuilt. The
others made safe landings.

Based on my experience, the it's more like 1 in 10 to 1 in 100.

Michael

Peter Duniho

November 25th 03, 03:10 PM

"Mike Rapoport" > wrote in message
link.net...
> Presumably all the pilots who had engine failures believed the same thing.

It's safest to assume that, but I suspect that in reality, only some small
subset even bothered to think hard enough about the issues to believe the
same thing. :)

Rich Stowell

November 25th 03, 03:57 PM

Sorry I can't point you to the "harder" data you're looking for, but
here's perhaps a little perspective on the issue:

According to one NTSB Study, pilots with fewer than either 500 hours
total time, or 100 hours in type, are more likely to encounter an
inadvertent stall/spin than to have a genuine engine failure (i.e.: a
random-event engine failure, not one attributed to such pilot errors
as fuel mismanagement).

In my case, over 6,400 hours with 5,600+ hours of instruction given
(mostly doing spin, emergency maneuver, aerobatic, and tailwheel
training -- the type of flying that might be considered harder on an
engine than more routine types of flying), I've had several
non-critical engine anomalies that were successfully dealt with,
including:

Prop stoppages during spins due to a couple of students hanging on so
tight to the throttle that it choked off the engine -- we call that
"fright idle";

Clogged fuel injectors during take-off that only revealed themselves
at full throttle;

Primer controls that were not truly "in and locked" which has lead to
prop stoppages during idle power landings.

In addition, two legitimate engine failures as follows:

The first, a fuel injector failure as we entered the traffic pattern
(after practicing off field landings, no less!) -- landed without
further incident;

The second, carb ice in a Champ during a flight review choked off the
engine during a touch and go -- touched down on the taxiway abeam the
departure end of the runway, hit a parked Porshe, bent the airplane,
walked away without so much as a scratch.

Rich
http://www.richstowell.com

(Captain Wubba) wrote in message >...
> Indeed. Interesting. But I'd still like to see some hard data. This is
> the kind of problem I run into...most of your pilot friends report
> that they have had a failure, but the majority of mine report none.
> And none of the 2000+ hour CFI types I asked (I asked 4 of them) have
> ever experienced an engine failure. My dad was a pilot with well over
> 12,000 hours and never had one. Another relative had fewer than 500
> hours total in his flying carrer and lost one on his first solo XC.
>
> I asked another A&P I ran into at the airport tonight, and he said he
> thought it should be at least 40,000 hours per in-flight engine
> failure, but really wasn't sure. Since a big part of flying is risk
> management, it would be very helpful to *really* know the risks
> involved. If the odds of losing an engine are 1 in 50,000 hours, then
> night/hard-IFR single-engine flying becomes a great deal more
> appealing than if it is 1 in 10,000 hours.
>
> I'll try to go over the NTSB data more thoroughly, I think a
> reasonable extrapolation would be that at least 1 in 4 in-flight
> engine failures (probably more) would end up in the NTSB database.
> But the cursory review I made earlier made me think the numbers were
> much less negative than I had considered before. And the opinions of
> these A&Ps are very interesting, because while failure might not
> require a total overhaul, it will require *something* to be done by a
> mechanic...and if these guys are seeing 30-40 engines make it to TBO
> for every one needing repair due to an in-flight failure, that might
> well support the 40,000 to 50,000 hour hypothesis.
>
> Cheers,
>
> Cap
>
>
> (Michael) wrote in message >...
> > (Captain Wubba) wrote
> > > Howdy. I was discussing with a friend of mine my concerns about flying
> > > single-engine planes at night or in hard IFR, due to the possibility
> > > of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> > > 3500 hours, and been around airplanes for a long time, so I tend to
> > > give credence to his experiences. He asked me how often I thought a
> > > piston engine had an in-flight engine failure. I guestimated once
> > > every 10,000 hours or so. He said that was *dramatically*
> > > over-estimating the failure rate. He said that in his experience it is
> > > at least 40,000 to 50,000 hours per in-flight engine failure.
> >
> > The only vaguely official number that I've ever seen came from a UK
> > accident report for a US-built twin. The UK investigators queried the
> > FAA on engine failure rates for the relevant engine, and the only
> > answer they got was that piston engines have failure rates on the
> > order of 1 in 1000 to 1 in 10000 hours. This is consistent with my
> > experience. I've had one non-fuel-related engine failure (partial,
> > but engine could only produce 20-30% power) in 1600+ hrs. Most people
> > I know with over 1500 GA hours have had an engine failure.
> >
> > 50,000 hours is not realistic. Excluding a few airline pilots (who
> > have ALL had engine failures) all my pilot friends together don't have
> > 50,000 hours, and quite a few of them have had engine failures.
> >
> > I've heard the maintenance shop thing before, but you need to realize
> > that most engine failures do not result in a major overhaul. Stuck
> > valves and cracked jugs mean that only a single jug is replaced;
> > failure of the carb or fuel injection system (my problem) affects only
> > that component. And oil loss will often seize an engine and make it
> > not worth overhauling.
> >
> > There are no real stats on engine failures because engine
> > manufacturers and the FAA don't want those stats to exist. The FAA
> > could create those stats simply by requiring pilots to report engine
> > failures for other than fuel exhaustion/contamination reasons, but
> > will not.
> >
> > The truth is, FAA certification requirements have frozen aircraft
> > piston engines in the past, and now they're less reliable than
> > automotive engines (not to mention ridiculously expensive).
> >
> > Michael

Tony Cox

November 25th 03, 04:12 PM

"Captain Wubba" > wrote in message
om...
>
> This is about risk management. I can manage the risks of fuel
> contamination or exhaustion very easily, if I exercise diligence and
> care. If those are no longer concerns, the primary engine-related
> concern becomes mechanical failure, and that's what I'm looking at.
>

I'm with you.
I'm most interested in anything which forces me down. Included
in that would be carburetor failure, fuel line breaks, engine fire,
as well as the engine deciding to punch a hole in the case...
stuff that I could never protect against by a thorough preflight.

I'd also be interested in survival statistics for forced landings at
night, over mountainous terrain, in cold weather etc. for *any*
reason (including self-induced fuel exhaustion). Then it is
easy to work out the risks.

--
Dr. Tony Cox
Citrus Controls Inc.
e-mail:
http://CitrusControls.com/

Ron Natalie

November 25th 03, 04:37 PM

"studentpilot" > wrote in message ...
>
> Know a bloke well with over 15'000 hours, he has had no engine failures.

My airplane has about 5500 hours over 50 years on it. It's had two fairly
major engine failures to my knowledge. I had the (mis)fortune of having
the second one which put an end to this engine (it's sitting in my basement
a new zero-time replacement is now installed).

Jeff Franks

November 25th 03, 05:12 PM

Knowing *NOTHING* about turbocharged engines, I was wondering. Would a loss
of the turbocharger still allow the engine to produce the same power as a
non-turbo engine of the same size at the same altitude? From the examples
I've read in this thread so far, 3 out of 4 are turbocharger failures.
Interesting.

"Bob Gardner" > wrote in message
news:G_vwb.294669$Tr4.929561@attbi_s03...
> In 7000 hours I had one engine "failure," which was just a loose hose
> between the turbocharger and intake manifold. Engine didn't really fail,
it
> just lost boost on that side. I've had some engine anomalies, but nothing
> that would meet the definition of failure. I would tend to agree that
> honest-to-goodness failures are very rare when considered in the context
of
> total operating hours for all powered aircraft.
>
> Bob Gardner
>
> "Captain Wubba" > wrote in message
> om...
> > Howdy. I was discussing with a friend of mine my concerns about flying
> > single-engine planes at night or in hard IFR, due to the possibility
> > of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> > 3500 hours, and been around airplanes for a long time, so I tend to
> > give credence to his experiences. He asked me how often I thought a
> > piston engine had an in-flight engine failure. I guestimated once
> > every 10,000 hours or so. He said that was *dramatically*
> > over-estimating the failure rate. He said that in his experience it is
> > at least 40,000 to 50,000 hours per in-flight engine failure. The
> > place where he works sometimes as a mechanic has plenty of planes come
> > in for overhauls and annuals, and he estimates that for every plane
> > that has had an engine failure before TBO, at least 20-30 make it to
> > TBO without any failure (which would extrapolate to a similar figure).
> > The flight school he teaches at has 7 Cessnas used for primary
> > training and rental that have flown at least 40,000 hours total in the
> > six years he has been there, and they have not experienced a single
> > engine failure.
> >
> > I emailed Lycoming, and (unsurprisingly) they told me they did not
> > keep records about engine failure rates.
> >
> > So I'd like to find out if anyone has done any objective analysis of
> > certificated, piston-engine failure rates in light airplanes. I have
> > seen all kinds of 'guesses', but little in the way of objective facts.
> > After analyzing NTSB accident data and comparing to annual GA
> > flight-hours, I'm starting to think my friend is on the right track,
> > but that is a relatively small sample, and has some methodologial
> > flaws. It's funny. I know 20,000 hour CFIs who have never had an
> > engine failure, and I also know 300 hour PP-ASELs who have had engine
> > failures.
> >
> > Just for giggles, I asked 8 pilot friends/relatives if they had ever
> > had an engine failure. The only 'yes' was a relative who lost an
> > engine after takeoff on his first solo cross-country in 1958. And I
> > know one other pilot who had an engine failure, who I wasn't able to
> > talk to.
> >
> > So what is it? If the engine-failure rate is one failure for every
> > 50,000 flight hours, I'll feel much less reticent about night/IFR
> > single-engine flying than if it is one in 10,000 hours. Anybody have
> > any facts or hard data, or have any idea where I might be able to
> > track some down?
> >
> > Thanks,
> >
> > Cap
>
>

Mike Rapoport

November 25th 03, 06:13 PM

True but I would assume that they thought that they had given the subject
adequate consideration. It is arogant to believe that everyone else is a
fool and you are not. My fovorite ezample are those pilots who are
confident that they could handle an IMC gyro failure when the record shows
that many (most?) cannot.

Mike
MU-2

"Peter Duniho" > wrote in message
...
> "Mike Rapoport" > wrote in message
> link.net...
> > Presumably all the pilots who had engine failures believed the same
thing.
>
> It's safest to assume that, but I suspect that in reality, only some small
> subset even bothered to think hard enough about the issues to believe the
> same thing. :)
>
>

Mike Rapoport

November 25th 03, 06:16 PM

It depends on the type of turbo failure. The typical failure is the bearing
in which case the engine will not make much, if any power.

Mike
MU-2

"Jeff Franks" > wrote in message
...
> Knowing *NOTHING* about turbocharged engines, I was wondering. Would a
loss
> of the turbocharger still allow the engine to produce the same power as a
> non-turbo engine of the same size at the same altitude? From the
examples
> I've read in this thread so far, 3 out of 4 are turbocharger failures.
> Interesting.
>
>
> "Bob Gardner" > wrote in message
> news:G_vwb.294669$Tr4.929561@attbi_s03...
> > In 7000 hours I had one engine "failure," which was just a loose hose
> > between the turbocharger and intake manifold. Engine didn't really fail,
> it
> > just lost boost on that side. I've had some engine anomalies, but
nothing
> > that would meet the definition of failure. I would tend to agree that
> > honest-to-goodness failures are very rare when considered in the context
> of
> > total operating hours for all powered aircraft.
> >
> > Bob Gardner
> >
> > "Captain Wubba" > wrote in message
> > om...
> > > Howdy. I was discussing with a friend of mine my concerns about flying
> > > single-engine planes at night or in hard IFR, due to the possibility
> > > of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> > > 3500 hours, and been around airplanes for a long time, so I tend to
> > > give credence to his experiences. He asked me how often I thought a
> > > piston engine had an in-flight engine failure. I guestimated once
> > > every 10,000 hours or so. He said that was *dramatically*
> > > over-estimating the failure rate. He said that in his experience it is
> > > at least 40,000 to 50,000 hours per in-flight engine failure. The
> > > place where he works sometimes as a mechanic has plenty of planes come

> > > in for overhauls and annuals, and he estimates that for every plane
> > > that has had an engine failure before TBO, at least 20-30 make it to
> > > TBO without any failure (which would extrapolate to a similar figure).
> > > The flight school he teaches at has 7 Cessnas used for primary
> > > training and rental that have flown at least 40,000 hours total in the
> > > six years he has been there, and they have not experienced a single
> > > engine failure.
> > >
> > > I emailed Lycoming, and (unsurprisingly) they told me they did not
> > > keep records about engine failure rates.
> > >
> > > So I'd like to find out if anyone has done any objective analysis of
> > > certificated, piston-engine failure rates in light airplanes. I have
> > > seen all kinds of 'guesses', but little in the way of objective facts.
> > > After analyzing NTSB accident data and comparing to annual GA
> > > flight-hours, I'm starting to think my friend is on the right track,
> > > but that is a relatively small sample, and has some methodologial
> > > flaws. It's funny. I know 20,000 hour CFIs who have never had an
> > > engine failure, and I also know 300 hour PP-ASELs who have had engine
> > > failures.
> > >
> > > Just for giggles, I asked 8 pilot friends/relatives if they had ever
> > > had an engine failure. The only 'yes' was a relative who lost an
> > > engine after takeoff on his first solo cross-country in 1958. And I
> > > know one other pilot who had an engine failure, who I wasn't able to
> > > talk to.
> > >
> > > So what is it? If the engine-failure rate is one failure for every
> > > 50,000 flight hours, I'll feel much less reticent about night/IFR
> > > single-engine flying than if it is one in 10,000 hours. Anybody have
> > > any facts or hard data, or have any idea where I might be able to
> > > track some down?
> > >
> > > Thanks,
> > >
> > > Cap
> >
> >
>
>

Peter Duniho

November 25th 03, 06:26 PM

"Jeff Franks" > wrote in message
...
> Knowing *NOTHING* about turbocharged engines, I was wondering. Would a
loss
> of the turbocharger still allow the engine to produce the same power as a
> non-turbo engine of the same size at the same altitude?

Depends on the failure, but sure...a failure like Bob describes simply
results in partial power loss, turning the engine into a close approximation
of the normally-aspirated version.

Ash Wyllie

November 25th 03, 06:32 PM

Captain Wubba opined on engine failures snipped

One partial, a bad mag, on a twin in 1400 hours.

-ash
for assistance dial MYCROFTXXX

Thomas Borchert

November 25th 03, 06:42 PM

Captain,

well, the stats are not easy to come by. Those who manage to get back
to the airport without incident never show up in the stats. Then you'd
have to exclude the "obviously dumb" things like running out of fuel or
fuel mismanagement. Those will be the VAST, ABSOLUTELY OVERWHELMING
majority. The comes the problem of maintenance. Obviously, many people
are willing to fly with total junk that's never been maintained
properly. Does that fall under "mechanical engine failure" or "pilot
error"?

--
Thomas Borchert (EDDH)

Mike Rapoport

November 25th 03, 07:38 PM

You are probably more likely to have an engine failure from maitenance than
from lack of maitenance.

Mike
MU-2

"Thomas Borchert" > wrote in message
...
> Captain,
>
> well, the stats are not easy to come by. Those who manage to get back
> to the airport without incident never show up in the stats. Then you'd
> have to exclude the "obviously dumb" things like running out of fuel or
> fuel mismanagement. Those will be the VAST, ABSOLUTELY OVERWHELMING
> majority. The comes the problem of maintenance. Obviously, many people
> are willing to fly with total junk that's never been maintained
> properly. Does that fall under "mechanical engine failure" or "pilot
> error"?
>
> --
> Thomas Borchert (EDDH)
>

Ditch

November 25th 03, 07:47 PM

>My fovorite ezample are those pilots who are
>confident that they could handle an IMC gyro failure when the record shows
>that many (most?) cannot.

Give me an engine failure any day. Gyro failure is my worst nightmare.

-John
*You are nothing until you have flown a Douglas, Lockheed, Grumman or North
American*

Peter Duniho

November 25th 03, 08:40 PM

"Mike Rapoport" > wrote in message
hlink.net...
> You are probably more likely to have an engine failure from maitenance
than
> from lack of maitenance.

Cute. But not really all that true, IMHO.

It depends on over how long a period of time you're talking about. If you
mean the instant after some maintenance is done, well sure...it's true (but
obviously so, and not interestingly so). But if you look at the same
question over 2000 hours of operation or one or two decades, I suspect that
lack of maintenance will show up as much more of an issue. The lack of oil
changes alone are likely to be a major problem, never mind the myriad of
fixable problems that would normally be detected during routine maintenance.

Pete

Ron Natalie

November 25th 03, 08:49 PM

"Peter Duniho" > wrote in message ...

> But if you look at the same
> question over 2000 hours of operation or one or two decades, I suspect that
> lack of maintenance will show up as much more of an issue. The lack of oil
> changes alone are likely to be a major problem, never mind the myriad of
> fixable problems that would normally be detected during routine maintenance.

Lack of use is the big killer. People base a lot of things on how many hours
in service an engine has, but they accumulate problems while sitting as well.

Michael

November 25th 03, 09:10 PM

"Mike Rapoport" > wrote
> No you are not making much sense. If you live and fly in the Midwest then
> the chances of survival after an engine failure are very different than
> flying over rough terrain.

Interestingly, this may not to be the case. The vast majority of
engine failure fatalities are the result of failure to maintain flying
speed and subsequent departure from controlled flight, not collision
with terrain.

Michael

Gene Seibel

November 25th 03, 10:30 PM

2500 hours. No failures where there was fuel in the tanks.
--
Gene Seibel
Hangar 131 - http://pad39a.com/gene/plane.html
Because I fly, I envy no one.

Michael

November 25th 03, 11:58 PM

"Mike Rapoport" > wrote
> True but I would assume that they thought that they had given the subject
> adequate consideration. It is arogant to believe that everyone else is a
> fool and you are not. My fovorite ezample are those pilots who are
> confident that they could handle an IMC gyro failure when the record shows
> that many (most?) cannot.

Yeah, I've heard that song before. Even believed it. Then I had my
AI tumble. At night. In IMC. On the climbout. While being
rerouted. In spite of what everyone told me, it was a complete
non-event. Used the copilot side AI for a while, but quickly decided
it was too much hassle, and flying partial panel was easier. Since I
still had the copilot side AI, I was legal to continue the flight -
and I did. Shot the NDB at my destination, but the weather was crap
and the runway lights were inop, so I couldn't get in. Wound up
shooting the ILS to near mins in the rain at my alternate. No big
deal. Gyro failure is not a big deal if you train properly. I could
even argue that without the backup AI, I would have been safer that
night because I would have had to turn back and land.

On the other hand, an engine failure in a single engine airplane under
the same conditions would have been very, very ugly.

Michael

Michael

November 26th 03, 12:16 AM

(Rich Stowell) wrote
> Sorry I can't point you to the "harder" data you're looking for, but
> here's perhaps a little perspective on the issue:
>
> According to one NTSB Study, pilots with fewer than either 500 hours
> total time, or 100 hours in type, are more likely to encounter an
> inadvertent stall/spin than to have a genuine engine failure (i.e.: a
> random-event engine failure, not one attributed to such pilot errors
> as fuel mismanagement).

Really? If that were true, then there would be hard data.

What the NTSB study REALLY says is that these low time pilots are more
likely to encounter an inadvertent stall/spin LEADING TO AN ACCIDENT
than to have a genuine engine failure LEADING TO AN ACCIDENT. This is
because an engine failure rarely leads to an accident (at least if the
ones known to me are any indication) but an inadvertent stall/spin
usually leads to an accident.

For that matter, most engine failure fatalities in light singles are
not the result of collision with terrain (which is usually survivable)
but of failure to maintain flying speed (which usually isn't). That's
basically a stall/spin anyway.

> In my case, over 6,400 hours ...
> ... two legitimate engine failures as follows:

2 in 6400 hours is very much consistent with my experience. It's also
very much consistent with the 1 in 1000 to 1 in 10000 number the FAA
provides.

Michael

David Megginson

November 26th 03, 01:04 AM

Michael wrote:

>>True but I would assume that they thought that they had given the subject
>>adequate consideration. It is arogant to believe that everyone else is a
>>fool and you are not. My fovorite ezample are those pilots who are
>>confident that they could handle an IMC gyro failure when the record shows
>>that many (most?) cannot.
>
> Yeah, I've heard that song before. Even believed it. Then I had my
> AI tumble. At night. In IMC. On the climbout. While being
> rerouted. In spite of what everyone told me, it was a complete
> non-event.

Thanks for the narrative -- it's useful information.

I'm curious where the statistics are that show that most pilots cannot
handle an AI failure in IMC. This FAA report

http://www1.faa.gov/fsdo/orl/files/advcir/P874052.TXT

states that vacuum failures are a factor in an average of 2 accidents per
year, and that there is an average of one vacuum-related accident for every
40,000 to 50,000 GA IFR flight plans filed. That doesn't tell us much,
though, since we don't know how many non-fatal vacuum failures occurred
during those flights.

All the best,

David

jim rosinski

November 26th 03, 01:11 AM

(Ditch) wrote

> >My fovorite ezample are those pilots who are
> >confident that they could handle an IMC gyro failure when the record shows
> >that many (most?) cannot.
>
> Give me an engine failure any day. Gyro failure is my worst nightmare.

Big-time ditto from me on this. Couple years ago I had a complete
gyro failure at night, fortunately not IFR. No warning, no nothing.
Just failed completely and instantly. Subsequent investigation of the
literature showed that this is not an uncommon failure mode.

I don't fly IFR any more, and probably won't till I'm flying a plane
with backup gyros. That's one nice thing about the new Cessnas,
they've got backups.

Jim Rosinski
N3825Q

Peter Duniho

November 26th 03, 01:37 AM

"Ron Natalie" > wrote in message
. ..
> Lack of use is the big killer. People base a lot of things on how many
hours
> in service an engine has, but they accumulate problems while sitting as
well.

Which is why I stipulated both an "hours of operation" and a "calendar time"
measure. Either one is significant, you are correct.

I don't particularly enjoy flying with an engine that's just had some major
work, but I'd sure take that over flying with an engine that's NEVER had ANY
work. And an engine that's gotten a few hours under its belt after
maintenance looks better every flight. :)

Pete

Tom S.

November 26th 03, 02:20 AM

"Mike Rapoport" > wrote in message
link.net...
> Presumably all the pilots who had engine failures believed the same thing.
>
And presumably, all the pilots who had engine failures engaged the same
level of preflight diligence.

Tom S.

November 26th 03, 02:25 AM

"Mike Rapoport" > wrote in message
hlink.net...
> True but I would assume that they thought that they had given the subject
> adequate consideration.

That would be a bad assumption.

> It is arogant to believe that everyone else is a
> fool and you are not.

That's true.

> My fovorite ezample are those pilots who are
> confident that they could handle an IMC gyro failure when the record shows
> that many (most?) cannot.

And how many have actually practiced this situation frequently?

What people believe and what they are capable of are to different things.
For example, in a survey a few years back, a bunch of people were polled on
their driving ability. Almost all (like 95%) said "superior", even those
with extensive driving citations. When taken out on test tracks, it was even
worse; most could not handle even the most routine emergencies. Then, how
often have any of us ever gone back to a driving school aften getting our
license when we turned sixteen?

> Mike
> MU-2
>
>
> "Peter Duniho" > wrote in message
> ...
> > "Mike Rapoport" > wrote in message
> > link.net...
> > > Presumably all the pilots who had engine failures believed the same
> thing.
> >
> > It's safest to assume that, but I suspect that in reality, only some
small
> > subset even bothered to think hard enough about the issues to believe
the
> > same thing. :)
> >
> >
>
>

Mike Rapoport

November 26th 03, 02:25 AM

I guess I don't agree. My experience is that maitenance creates many
problems. I agree that the engine will last longer if you change the oil
more frequently but changing the oil doesn't prevent failures. Routine
maitenance doesn't detect impending connecting rod failures, turbo bearing
about the sieze ect. I have seen and heard of too many oil leaks, fuel
leaks, rubbing tubes and various parts coming loose or falling off...all
caused by "maitenance".

Mike
MU-2

"Peter Duniho" > wrote in message
...
> "Mike Rapoport" > wrote in message
> hlink.net...
> > You are probably more likely to have an engine failure from maitenance
> than
> > from lack of maitenance.
>
> Cute. But not really all that true, IMHO.
>
> It depends on over how long a period of time you're talking about. If you
> mean the instant after some maintenance is done, well sure...it's true
(but
> obviously so, and not interestingly so). But if you look at the same
> question over 2000 hours of operation or one or two decades, I suspect
that
> lack of maintenance will show up as much more of an issue. The lack of
oil
> changes alone are likely to be a major problem, never mind the myriad of
> fixable problems that would normally be detected during routine
maintenance.
>
> Pete
>
>

Tom S.

November 26th 03, 02:32 AM

"Mike Rapoport" > wrote in message
link.net...
> I don't have any personally but I have a friend that has had three in
> 3500hrs. One connecting rod failure in a 210. A crankshaft failure in an
> Azetec and I forget the details of the third failure. It has been
estimated
> that 10% of Malibus have had inflight engine failures of some kind.
>

It'd be interesting to know the maintenance history of those birds that did
have failures (skimped maintenance, etc).

It's also be interesting to know the total operating hours of the Malibu
fleet, Lycoming vs. Continental...

Mike Rapoport

November 26th 03, 02:38 AM

I have also had a gyro fail (in a Turbo Lance that had only one AI) in IMC
flight along with an partial electrical failure (lost the alternator) and
managed to get to my destination after shooting a localizer approach to
pretty much minimiums with a Garmin 12XL that I had to program the approach
waypoints into while flying partial panel AND it was in freezing rain. No
****, this really happened. Every emergency I have ever had was on that one
flight which happened to be my first serious IFR flight after getting the IR
(accross the Sierra From Minden to San Jose in a major blizzard)

That experience doesn't convince me that there are not plenty of senarios
where it wouldn't have had a happy ending.

Mike
MU-2

"Michael" > wrote in message
om...
> "Mike Rapoport" > wrote
> > True but I would assume that they thought that they had given the
subject
> > adequate consideration. It is arogant to believe that everyone else is
a
> > fool and you are not. My fovorite ezample are those pilots who are
> > confident that they could handle an IMC gyro failure when the record
shows
> > that many (most?) cannot.
>
> Yeah, I've heard that song before. Even believed it. Then I had my
> AI tumble. At night. In IMC. On the climbout. While being
> rerouted. In spite of what everyone told me, it was a complete
> non-event. Used the copilot side AI for a while, but quickly decided
> it was too much hassle, and flying partial panel was easier. Since I
> still had the copilot side AI, I was legal to continue the flight -
> and I did. Shot the NDB at my destination, but the weather was crap
> and the runway lights were inop, so I couldn't get in. Wound up
> shooting the ILS to near mins in the rain at my alternate. No big
> deal. Gyro failure is not a big deal if you train properly. I could
> even argue that without the backup AI, I would have been safer that
> night because I would have had to turn back and land.
>
> On the other hand, an engine failure in a single engine airplane under
> the same conditions would have been very, very ugly.
>
> Michael

R. Hubbell

November 26th 03, 03:35 AM

On Tue, 25 Nov 2003 14:40:02 GMT
"Mike Rapoport" > wrote:

> No you are not making much sense. If you live and fly in the Midwest then
> the chances of survival after an engine failure are very different than
> flying over rough terrain.

I'd like to see the stats from the Capt. Wubba. Unless you are privvy to
some, can you share it here? Or is this from your experience?

For example I heard a stat that surprised me as it was counter-intuitive.
There are more fatal accidents by teen and early twenties car drivers in
rural areas then in urban areas. But once I had the explanatin it made more
sense. The fatality rate goes up since the speed goes way up out in the
country.

R. Hubbell

>
> Mike
> MU-2
>
>
> "R. Hubbell" > wrote in message
> news:%oDwb.3381$ZE1.73@fed1read04...
> > On 24 Nov 2003 11:31:57 -0800
> > (Captain Wubba) wrote:
> >
> > > Howdy. I was discussing with a friend of mine my concerns about flying
> > > single-engine planes at night or in hard IFR, due to the possibility
> > > of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> > > 3500 hours, and been around airplanes for a long time, so I tend to
> > > give credence to his experiences. He asked me how often I thought a
> > > piston engine had an in-flight engine failure. I guestimated once
> > > every 10,000 hours or so. He said that was *dramatically*
> > > over-estimating the failure rate. He said that in his experience it is
> > > at least 40,000 to 50,000 hours per in-flight engine failure. The
> > > place where he works sometimes as a mechanic has plenty of planes come
> > > in for overhauls and annuals, and he estimates that for every plane
> > > that has had an engine failure before TBO, at least 20-30 make it to
> > > TBO without any failure (which would extrapolate to a similar figure).
> > > The flight school he teaches at has 7 Cessnas used for primary
> > > training and rental that have flown at least 40,000 hours total in the
> > > six years he has been there, and they have not experienced a single
> > > engine failure.
> > >
> > > I emailed Lycoming, and (unsurprisingly) they told me they did not
> > > keep records about engine failure rates.
> > >
> > > So I'd like to find out if anyone has done any objective analysis of
> > > certificated, piston-engine failure rates in light airplanes. I have
> > > seen all kinds of 'guesses', but little in the way of objective facts.
> > > After analyzing NTSB accident data and comparing to annual GA
> > > flight-hours, I'm starting to think my friend is on the right track,
> > > but that is a relatively small sample, and has some methodologial
> > > flaws. It's funny. I know 20,000 hour CFIs who have never had an
> > > engine failure, and I also know 300 hour PP-ASELs who have had engine
> > > failures.
> > >
> > > Just for giggles, I asked 8 pilot friends/relatives if they had ever
> > > had an engine failure. The only 'yes' was a relative who lost an
> > > engine after takeoff on his first solo cross-country in 1958. And I
> > > know one other pilot who had an engine failure, who I wasn't able to
> > > talk to.
> > >
> > > So what is it? If the engine-failure rate is one failure for every
> > > 50,000 flight hours, I'll feel much less reticent about night/IFR
> > > single-engine flying than if it is one in 10,000 hours. Anybody have
> > > any facts or hard data, or have any idea where I might be able to
> > > track some down?
> > >
> > > Thanks,
> > >
> > > Cap
> >
> >
> > I think it's a reasonable question to ask bnut to me it's more important
> to
> > know how many engine failures resulted in fatalities since if the engine
> > failed and they walked away from it then who the hell cares what failed
> > as long as you live to fly again. Am I making any sense? The stat I'm
> > tinking of would be engine failures where a fatality resulted and that
> > number will be many more hours than just a engine failure and that's
> > the number that I'll live close to if I have to live close to some fear
> > factor. Even if I'm carried away on a stretcher it beats paying the
> > down mortgage. The engine will just be the last thing I'd think of.
> >
> > Do you know what that does to your numbers when you include fatals?
> >
> >
> > R. Hubbell
> >
> >
> >
>
>

R. Hubbell

November 26th 03, 03:35 AM

On Tue, 25 Nov 2003 23:31:50 +1000
"B" > wrote:

> Night VFR engine failure:
>
> 1. turn on landing lights,
>
> 2. if you don't like what you see, turn them back off!

You may want to shut off the master with an engine failure, unless you're
sure it's ok to leave it on.

>
> Hope this helps,
> Peter
>
>

R. Hubbell

November 26th 03, 03:45 AM

On 25 Nov 2003 05:56:17 -0800
(Captain Wubba) wrote:

> "R. Hubbell" > wrote in message news:<%oDwb.3381$ZE1.73@fed1read04>...
> > On 24 Nov 2003 11:31:57 -0800
> > (Captain Wubba) wrote:
> >
> > > Howdy. I was discussing with a friend of mine my concerns about flying
> > > single-engine planes at night or in hard IFR, due to the possibility
> > > of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> > > 3500 hours, and been around airplanes for a long time, so I tend to
> > > give credence to his experiences. He asked me how often I thought a
> > > piston engine had an in-flight engine failure. I guestimated once
> > > every 10,000 hours or so. He said that was *dramatically*
> > > over-estimating the failure rate. He said that in his experience it is
> > > at least 40,000 to 50,000 hours per in-flight engine failure. The
> > > place where he works sometimes as a mechanic has plenty of planes come
> > > in for overhauls and annuals, and he estimates that for every plane
> > > that has had an engine failure before TBO, at least 20-30 make it to
> > > TBO without any failure (which would extrapolate to a similar figure).
> > > The flight school he teaches at has 7 Cessnas used for primary
> > > training and rental that have flown at least 40,000 hours total in the
> > > six years he has been there, and they have not experienced a single
> > > engine failure.
> > >
> > > I emailed Lycoming, and (unsurprisingly) they told me they did not
> > > keep records about engine failure rates.
> > >
> > > So I'd like to find out if anyone has done any objective analysis of
> > > certificated, piston-engine failure rates in light airplanes. I have
> > > seen all kinds of 'guesses', but little in the way of objective facts.
> > > After analyzing NTSB accident data and comparing to annual GA
> > > flight-hours, I'm starting to think my friend is on the right track,
> > > but that is a relatively small sample, and has some methodologial
> > > flaws. It's funny. I know 20,000 hour CFIs who have never had an
> > > engine failure, and I also know 300 hour PP-ASELs who have had engine
> > > failures.
> > >
> > > Just for giggles, I asked 8 pilot friends/relatives if they had ever
> > > had an engine failure. The only 'yes' was a relative who lost an
> > > engine after takeoff on his first solo cross-country in 1958. And I
> > > know one other pilot who had an engine failure, who I wasn't able to
> > > talk to.
> > >
> > > So what is it? If the engine-failure rate is one failure for every
> > > 50,000 flight hours, I'll feel much less reticent about night/IFR
> > > single-engine flying than if it is one in 10,000 hours. Anybody have
> > > any facts or hard data, or have any idea where I might be able to
> > > track some down?
> > >
> > > Thanks,
> > >
> > > Cap
> >
> >
> > I think it's a reasonable question to ask bnut to me it's more important to
> > know how many engine failures resulted in fatalities since if the engine
> > failed and they walked away from it then who the hell cares what failed
> > as long as you live to fly again. Am I making any sense? The stat I'm
> > tinking of would be engine failures where a fatality resulted and that
> > number will be many more hours than just a engine failure and that's
> > the number that I'll live close to if I have to live close to some fear
> > factor. Even if I'm carried away on a stretcher it beats paying the
> > down mortgage. The engine will just be the last thing I'd think of.
> >
> > Do you know what that does to your numbers when you include fatals?
> >
> >
> > R. Hubbell
>
>
> Actually I'd really like to know that too. When I delve more deeply
> into the NTSB stuff, I'll break out fatalities. And it does
> relate....I am most concerned with IFR and night flying, with this
> specific question. An engine loss at altitude in day VFR should almost
> never be fatal; it probably shouldn't even bend the plane very often.
> But at night or in hard IFR I'd expect the fatality rate to be rather
> high. What it is exactly will be interesting to find out. Certainly it
> is easier to find out fatalities than it is total engine failures. If
> I can glean these numbers from the NTSB database, I'll let you know.
> Since this is mostly aboiut risk management, it will be interesting to
> really know the risks *after* the engine failure as well.

I wonder if the ASF Air Safety Foundation can help out here? They live
and breathe this stuff.

I'd expect the number of hours flown per failure that resulted in a fatal to
be very high and of course decreasing with worsening conditions. But it
may be hard to find out the cause as others have said. It seems like
you're interested in hard and unexpected failures. I think in a lot
of ways we, as pilots, are fortunate to have so much data to look to
but it can be misleading if it's not comprehensive enough. So far the
data's pretty good and it's useful still. But I have never looked at
car crash data much to improve how I drive. Although I know more accidents
occur in the slow lane and fewer in the fast lane so I try to avoid the
slow lane but I didn't really need accident data to reach that conclusion.
My point is just that we like to know how people paid down their mortgage,
early and suddenly as a reminder that it happens and to learn from and
avoid the same mistake.

Rick

>
> Cheers,
>
> Cap

Tom S.

November 26th 03, 03:47 AM

"Tom S." > wrote in message news:...
>
> "Mike Rapoport" > wrote in message
> link.net...

http://www.ntsb.gov/NTSB/brief.asp?ev_id=20001212X20796&key=1

In sum...

"The National Transportation Safety Board determines the probable cause(s)
of this incident as follows:

The failure of a number one cylinder connecting rod bolt due to
under-torquing during engine major overhaul. "

Peter Duniho

November 26th 03, 04:10 AM

"Mike Rapoport" > wrote in message
link.net...
> [...] I have seen and heard of too many oil leaks, fuel
> leaks, rubbing tubes and various parts coming loose or falling off...all
> caused by "maitenance".

Well, granted, the engines on your plane require a much more specialized
maintenance crew than the one Lycoming on mine. But in spite of the very
real possibility of human error during maintenance, as far as I know more
engine failures are prevented by maintenance than are caused by it. I would
be very surprised if you could find statistics to the contrary.

Pete

jim rosinski

November 26th 03, 04:20 AM

(Michael) wrote

> Yeah, I've heard that song before. Even believed it. Then I had my
> AI tumble. At night. In IMC. On the climbout. While being
> rerouted.
> [...]
> Gyro failure is not a big deal if you train properly.

Well, for those of us less studly than this, I'd still take an engine
failure over gyro failure in IMC under most conditions. Maybe given
the time/money to train "properly" gyro failure isn't such a major
emergency. But I don't have either the time or the money, so this
instrument-rated pilot isn't flying IFR till he gets a plane with
backup gyros or electric AI.

> On the other hand, an engine failure in a single engine airplane under
> the same conditions would have been very, very ugly.

Good point. Climbout is a really horrible time for an engine failure.
In cruise I'm still much more afraid of gyro failure though. As I
said in another post on this subject, some of the reason for this is
that it often happens (and did to me) with little or now warning.

Jim Rosinski
N3825Q

Snowbird

November 26th 03, 05:01 AM

(Michael) wrote in message >...

> Yeah, I've heard that song before. Even believed it. Then I had my
> AI tumble. At night. In IMC. On the climbout. While being
> rerouted. In spite of what everyone told me, it was a complete
> non-event. <....> Gyro failure is not a big deal if you train properly.

I really don't want to restart that whole thread but FWIW:

One observation from the recent ASF/FAA vacuum failure study
was that pilots who lost only their AI (electric HSI did not
fail) did not lose control of the airplane, while a significant
number of pilots (same aircraft) lost control when they lost
both. There was no correlation to time in type or total time.

This result suggests to me that it might be a mistake to
extrapolate from "lose AI no problem" to "lose gyros no
problem".

> On the other hand, an engine failure in a single engine airplane under
> the same conditions would have been very, very ugly.

No argument there. But certainly there are a number of pilots
who have found vacuum system failure in night IMC to be fatally
ugly.

There are currently no "real stats" which prove or disprove
the contention that this ugliness is entirely due to improper
training.

Them's the facts,
Sydney

Snowbird

November 26th 03, 05:03 AM

(Ditch) wrote in message >...
> >My fovorite ezample are those pilots who are
> >confident that they could handle an IMC gyro failure when the record shows
> >that many (most?) cannot.

> Give me an engine failure any day. Gyro failure is my worst nightmare.

In a SE airplane w/ an engine powered vacuum pump and w/out a backup
electric pump or backup electric gyros, engine failure will become
gyro failure in a minute or so.

Sydney

Snowbird

November 26th 03, 05:19 AM

(Captain Wubba) wrote in message >...
> Andrew Rowley > wrote in message >...
> > Why do you exclude fuel exhaustion, fuel contamination etc? Don't they
> > happen if you're IFR?

> > If you're IFR or at night it doesn't really matter WHY it stops.

> Because I can control these problems. If I do a proper preflight, the
> probability of fuel contamination is very, very low. If I do the
> proper fuel calculations and check the fuel levels and carry proper
> reserves, I'm not going to run out of gas.

"Cap",

Just curious.

When you fill the tanks after each cross country flight, do you
calculate the fuel you actually had remaining, and compare it
to your calculated fuel reserve?

If so, have they ever disagreed?

I really don't want to go there again either -- this topic has been
thrashed out previously and anyone who cares could go Google for it,
but there are a number of factors which make fuel calculations for
a GA aircraft somewhat more uncertain than most pilots would apparently
like to believe.

These uncertainties include:
*aircraft parked on a slope while refueling
*aircraft tachometer not calibrated and no fuel flow meter
*leakage of fuel in flight
*OAT colder than expected or charted and pilot doesn't compensate
*and so forth

We've had our "ulp" moment where we landed safely and fueled,
and while we had legal reserves we in fact had considerably
less fuel than our proper calculations and preflight checking
led us to expect (for one or more of the above reasons), and
it would have bitten us on the butt if we'd had to exercise
"Plan B".

I don't disagree at all with the philosophy that one should
exercise control to minimize whatever risks one can.

I just feel that it's a mistake to conclude that no pilot
who runs out of fuel in flight did so, or that no pilot
who does so will ever run out of fuel in flight.

Regards,
Sydney

Ron Rosenfeld

November 26th 03, 12:50 PM

On 24 Nov 2003 11:31:57 -0800, (Captain Wubba)
wrote:

>
>So I'd like to find out if anyone has done any objective analysis of
>certificated, piston-engine failure rates in light airplanes. I have
>seen all kinds of 'guesses', but little in the way of objective facts.

There are variations depending on the engine and aircraft. Whether these
are significant is unknown, as the universe is too small to afford
significance to the statistics.

Last year, in the March and June issues (2002) Aviation Consumer published
studies on accidents in light and heavy single engine a/c of the type most
of us here fly.

The total accident rate from all causes was on the order of 3.8/100,000 hrs
and the fatal accident rate from all causes was on the order of 1.1/100,000
hrs.

Engine failures (NOT including fuel exhaustion) comprised about 21% of the
accidents so, since fatal accidents are likely all reported to the NTSB, I
think one could assume a fatal engine failure accident rate on the order of
1/500,000 hrs in this group of aircraft.

Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Captain Wubba

November 26th 03, 01:52 PM

"Mike Rapoport" > wrote in message . net>...
> Presumably all the pilots who had engine failures believed the same thing.
>

Did they? I see pilots take off all the time with no preflight. I see
plenty of aircraft takeoff without having had their pilots sample the
fuel, look at the oil, do a runup...even take a quick look in the
tanks. No just pattern flights either. Just the other day, when I
flying to Nashville, I saw a guy who I knew was headed to Charleston,
SC in an A36 just show up at the airport, pile his wife and kid in the
plane and go. They were late, apparently...no time for a preflight. In
a single-engine plane, over mountains, at night. He trusted the FBO to
have filled up his tanks...he trusted that his oil level was where it
should have been...he trusted that there was no water in his tanks, or
that they were not accidently filled with Jet-A. You might be
right...he might have thought he was managing the risks, but obviously
he wasn't. It just didn't catch up to him *this* time.

Paul Craig's excellent book 'The Killing Zone: How & Why Pilots Die'
talks about 'creeping complacency'. When we were student pilots we
used pre-flight checklists all the time. Checked everything. AFter a
few hundred hours, many non-professional pilots have allowed
themselves to truncate their preflight to a quick walk around, oil
check, and tank level. Many don't even do that.

To me, this is about risk management. I *can* manage the risks of
running out of gas. I *can* manage the risks of fuel contamination.
Just by being diligent about my preflights. But I can't preflight my
way out of a thrown rod...which is why I'd like to know more about
their liklihood.

Cheers,

Cap

> Mike
> MU-2
>
>
> "Captain Wubba" > wrote in message
> om...
> > Andrew Rowley > wrote in message
> >...
> > > studentpilot > wrote:
> > >
> > > >Know a bloke well with over 15'000 hours, he has had no engine
> failures.
> > > >He has had however 4 self inficted engine failures, these were fuel
> > > >system failures. Mostly failure to put enough in, failure to check
> > > >for water contamination properly, failure to know the aircraft fuel
> > > >system. This blokes expirence is all single engine, going from little
> > > >Lyc's to Radial's and turbine.
> > >
> > > Why do you exclude fuel exhaustion, fuel contamination etc? Don't they
> > > happen if you're IFR?
> > >
> > > If you're IFR or at night it doesn't really matter WHY it stops.
> >
> > Because I can control these problems. If I do a proper preflight, the
> > probability of fuel contamination is very, very low. If I do the
> > proper fuel calculations and check the fuel levels and carry proper
> > reserves, I'm not going to run out of gas.
> >
> > This is about risk management. I can manage the risks of fuel
> > contamination or exhaustion very easily, if I exercise diligence and
> > care. If those are no longer concerns, the primary engine-related
> > concern becomes mechanical failure, and that's what I'm looking at.
> >
> >
> > Cap

Michael

November 26th 03, 02:24 PM

(Snowbird) wrote
> In a SE airplane w/ an engine powered vacuum pump and w/out a backup
> electric pump or backup electric gyros, engine failure will become
> gyro failure in a minute or so.

Not true unless the engine seizes. If it keeps windmilling, the gyros
will keep spinning.

Michael

Captain Wubba

November 26th 03, 02:31 PM

(Snowbird) wrote in message >...
> (Captain Wubba) wrote in message >...
> > Andrew Rowley > wrote in message >...
> > > Why do you exclude fuel exhaustion, fuel contamination etc? Don't they
> > > happen if you're IFR?
>
> > > If you're IFR or at night it doesn't really matter WHY it stops.
>
> > Because I can control these problems. If I do a proper preflight, the
> > probability of fuel contamination is very, very low. If I do the
> > proper fuel calculations and check the fuel levels and carry proper
> > reserves, I'm not going to run out of gas.
>
> "Cap",
>
> Just curious.
>
> When you fill the tanks after each cross country flight, do you
> calculate the fuel you actually had remaining, and compare it
> to your calculated fuel reserve?

Not after every one. But after some percentage...probably around 1/4
of the time. I've caught one FBO that didn't give me all the fuel I
asked for this way. They were not trying to cheat me, but it was a
miscomminication with their lineboy. Wasn't a serious problem...I
always carry at least a 2 hour reserve (60 gallon tanks on a Beech
Musketeer that drinks 9 GPH), so I got in with one and a half hour
reserve instead of 2.5. Hard to notice how 10 gallons looks in a tank.
>
> If so, have they ever disagreed?

Yep. In the case above, and when we were having carb problems. Part of
the reason we started suspsecting carb problems.

>
> I really don't want to go there again either -- this topic has been
> thrashed out previously and anyone who cares could go Google for it,
> but there are a number of factors which make fuel calculations for
> a GA aircraft somewhat more uncertain than most pilots would apparently
> like to believe.
>
> These uncertainties include:
> *aircraft parked on a slope while refueling
> *aircraft tachometer not calibrated and no fuel flow meter
> *leakage of fuel in flight
> *OAT colder than expected or charted and pilot doesn't compensate
> *and so forth

Indeed. But I keep two hour reserves on cross country flights in my
Musketeer. No reason not to...it's almost always just me and my wife
(and soon our little one:), so no reason not to carry plenty of
gas...when you have 6-hour tanks and a 3-hour bladder, you might as
well put the extra tank space to use :)

>
> We've had our "ulp" moment where we landed safely and fueled,
> and while we had legal reserves we in fact had considerably
> less fuel than our proper calculations and preflight checking
> led us to expect (for one or more of the above reasons), and
> it would have bitten us on the butt if we'd had to exercise
> "Plan B".
>
> I don't disagree at all with the philosophy that one should
> exercise control to minimize whatever risks one can.
>
> I just feel that it's a mistake to conclude that no pilot
> who runs out of fuel in flight did so, or that no pilot
> who does so will ever run out of fuel in flight.

I didn't mean to imply that. But that's part of the risk management. I
eat lunch at the airport almost every day, sitting in the GA lot
watching the planes. And you would be stunned by the number of pilots
I see who don't do *any* preflight. We've had two fuel-exhaustion
crashes at my airport over the last decade or so. One unfortunately
killed two innocent people on the ground as well as the pilot. And
both were directly caused by *astounding* stupidity on the part of the
pilots. From reviewing the NTSB database, it appears the majority of
fuel-exhaustion accidents are not the result of a simple
miscalculation. They tend to be a chain of bad decisions (as do most
pilot-error accidents). An example is the one I mentioned above. A
pilot rented a 152, flew it out to Indiana for the day (1.5 hours),
flew a buddy around (45 minutes), then tried to fly back (2 hours)
fully aware that the tanks held 4 hours of fuel. He didn't want to pay
the higher prices at the Indiana airport. He wasn't night current, but
flew back at night. He ran out of gas, then tried to land *into*
traffic on a highway at night. Killed himself, and two women in the
minivan he flew into. Stunning stupidity all the way around.

I'm sure there are many fuel-exhaustion accidents that happen despite
good efforts by the pilot to be diligent. But I think they are much
less common than those that happen because the pilot abrogated his
responsibility to manage all of the risks he could.

>
> Regards,
> Sydney

Cheers,

Cap

Michael

November 26th 03, 02:33 PM

(Snowbird) wrote
> One observation from the recent ASF/FAA vacuum failure study
> was that pilots who lost only their AI (electric HSI did not
> fail) did not lose control of the airplane, while a significant
> number of pilots (same aircraft) lost control when they lost
> both. There was no correlation to time in type or total time.
>
> This result suggests to me that it might be a mistake to
> extrapolate from "lose AI no problem" to "lose gyros no
> problem".

That's somewhat valid. I don't worry about this situation for two
reasons: First, I have dual vacuum pumps, so loss of both gyros
simultaneously is very, very unlikely. The same is true of a wet pump
setup. I've already made my feelings about flying IMC with a single
dry pump and no backups well known, but in case anyone missed it -
it's stooopid. Second, my GPS has an HSI mode.

The reason I say it's somewhat valid is this - my (admittedly somewhat
limited) experience as an instrument instructor is that most people
miss having the DG a lot more than they miss having the AI. While
there is a case to be made that a jet can't be flown without an AI (no
jet crew that lost all attitude indicators in IMC has ever survived)
light piston airplanes most certainly can be.

> There are currently no "real stats" which prove or disprove
> the contention that this ugliness is entirely due to improper
> training.

No, but that's the way to bet. It's certainly how my insurance
company is betting - I'm now required to take a full IPC with engine
cuts every year in make and model, regardless of recency of
experience, if I want to keep my relatively low rates.

Michael

Big John

November 26th 03, 06:05 PM

Mike

As they say, "Train for the worst. Hope for the best".

Big John

On Wed, 26 Nov 2003 02:38:51 GMT, "Mike Rapoport"
> wrote:

>I have also had a gyro fail (in a Turbo Lance that had only one AI) in IMC
>flight along with an partial electrical failure (lost the alternator) and
>managed to get to my destination after shooting a localizer approach to
>pretty much minimiums with a Garmin 12XL that I had to program the approach
>waypoints into while flying partial panel AND it was in freezing rain. No
>****, this really happened. Every emergency I have ever had was on that one
>flight which happened to be my first serious IFR flight after getting the IR
>(accross the Sierra From Minden to San Jose in a major blizzard)
>
>That experience doesn't convince me that there are not plenty of senarios
>where it wouldn't have had a happy ending.
>
>Mike
>MU-2
>
>
>"Michael" > wrote in message
om...
>> "Mike Rapoport" > wrote
>> > True but I would assume that they thought that they had given the
>subject
>> > adequate consideration. It is arogant to believe that everyone else is
>a
>> > fool and you are not. My fovorite ezample are those pilots who are
>> > confident that they could handle an IMC gyro failure when the record
>shows
>> > that many (most?) cannot.
>>
>> Yeah, I've heard that song before. Even believed it. Then I had my
>> AI tumble. At night. In IMC. On the climbout. While being
>> rerouted. In spite of what everyone told me, it was a complete
>> non-event. Used the copilot side AI for a while, but quickly decided
>> it was too much hassle, and flying partial panel was easier. Since I
>> still had the copilot side AI, I was legal to continue the flight -
>> and I did. Shot the NDB at my destination, but the weather was crap
>> and the runway lights were inop, so I couldn't get in. Wound up
>> shooting the ILS to near mins in the rain at my alternate. No big
>> deal. Gyro failure is not a big deal if you train properly. I could
>> even argue that without the backup AI, I would have been safer that
>> night because I would have had to turn back and land.
>>
>> On the other hand, an engine failure in a single engine airplane under
>> the same conditions would have been very, very ugly.
>>
>> Michael
>

Tobias Schnell

November 26th 03, 06:32 PM

750 hrs here (OK, 250 of them in gliders). One impending failure due
to broken shaft seal on the crankcase. The engine did not show oil
pressure any more, but I made it back to the airport with the engine
still running at near idle. It happened on the climbout, about 3000
AGL.

Tobias

Big John

November 26th 03, 06:36 PM

Rich

Some other data to put in the pot.

The Air Force paid some one (Rand Corporation or some other think
tank) to do a study on accidents vs flying time.

It basically came out that there were two spikes, one around 500 hours
and the other around 1000 hours. The 500 hour accidents were
attributed to cocky over confidence. Not sure right now what the 1000
spike was but it was caused by something we could train around or
change procedures, etc. to reduce as I recall.

Big John

On 25 Nov 2003 07:57:26 -0800, (Rich Stowell)
wrote:

>Sorry I can't point you to the "harder" data you're looking for, but
>here's perhaps a little perspective on the issue:
>
>According to one NTSB Study, pilots with fewer than either 500 hours
>total time, or 100 hours in type, are more likely to encounter an
>inadvertent stall/spin than to have a genuine engine failure (i.e.: a
>random-event engine failure, not one attributed to such pilot errors
>as fuel mismanagement).
>
>
>In my case, over 6,400 hours with 5,600+ hours of instruction given
>(mostly doing spin, emergency maneuver, aerobatic, and tailwheel
>training -- the type of flying that might be considered harder on an
>engine than more routine types of flying), I've had several
>non-critical engine anomalies that were successfully dealt with,
>including:
>
>Prop stoppages during spins due to a couple of students hanging on so
>tight to the throttle that it choked off the engine -- we call that
>"fright idle";
>
>Clogged fuel injectors during take-off that only revealed themselves
>at full throttle;
>
>Primer controls that were not truly "in and locked" which has lead to
>prop stoppages during idle power landings.
>
>
>In addition, two legitimate engine failures as follows:
>
>The first, a fuel injector failure as we entered the traffic pattern
>(after practicing off field landings, no less!) -- landed without
>further incident;
>
>The second, carb ice in a Champ during a flight review choked off the
>engine during a touch and go -- touched down on the taxiway abeam the
>departure end of the runway, hit a parked Porshe, bent the airplane,
>walked away without so much as a scratch.
>
>Rich
>http://www.richstowell.com
>
>
>
(Captain Wubba) wrote in message >...
>> Indeed. Interesting. But I'd still like to see some hard data. This is
>> the kind of problem I run into...most of your pilot friends report
>> that they have had a failure, but the majority of mine report none.
>> And none of the 2000+ hour CFI types I asked (I asked 4 of them) have
>> ever experienced an engine failure. My dad was a pilot with well over
>> 12,000 hours and never had one. Another relative had fewer than 500
>> hours total in his flying carrer and lost one on his first solo XC.
>>
>> I asked another A&P I ran into at the airport tonight, and he said he
>> thought it should be at least 40,000 hours per in-flight engine
>> failure, but really wasn't sure. Since a big part of flying is risk
>> management, it would be very helpful to *really* know the risks
>> involved. If the odds of losing an engine are 1 in 50,000 hours, then
>> night/hard-IFR single-engine flying becomes a great deal more
>> appealing than if it is 1 in 10,000 hours.
>>
>> I'll try to go over the NTSB data more thoroughly, I think a
>> reasonable extrapolation would be that at least 1 in 4 in-flight
>> engine failures (probably more) would end up in the NTSB database.
>> But the cursory review I made earlier made me think the numbers were
>> much less negative than I had considered before. And the opinions of
>> these A&Ps are very interesting, because while failure might not
>> require a total overhaul, it will require *something* to be done by a
>> mechanic...and if these guys are seeing 30-40 engines make it to TBO
>> for every one needing repair due to an in-flight failure, that might
>> well support the 40,000 to 50,000 hour hypothesis.
>>
>> Cheers,
>>
>> Cap
>>
>>
>> (Michael) wrote in message >...
>> > (Captain Wubba) wrote
>> > > Howdy. I was discussing with a friend of mine my concerns about flying
>> > > single-engine planes at night or in hard IFR, due to the possibility
>> > > of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
>> > > 3500 hours, and been around airplanes for a long time, so I tend to
>> > > give credence to his experiences. He asked me how often I thought a
>> > > piston engine had an in-flight engine failure. I guestimated once
>> > > every 10,000 hours or so. He said that was *dramatically*
>> > > over-estimating the failure rate. He said that in his experience it is
>> > > at least 40,000 to 50,000 hours per in-flight engine failure.
>> >
>> > The only vaguely official number that I've ever seen came from a UK
>> > accident report for a US-built twin. The UK investigators queried the
>> > FAA on engine failure rates for the relevant engine, and the only
>> > answer they got was that piston engines have failure rates on the
>> > order of 1 in 1000 to 1 in 10000 hours. This is consistent with my
>> > experience. I've had one non-fuel-related engine failure (partial,
>> > but engine could only produce 20-30% power) in 1600+ hrs. Most people
>> > I know with over 1500 GA hours have had an engine failure.
>> >
>> > 50,000 hours is not realistic. Excluding a few airline pilots (who
>> > have ALL had engine failures) all my pilot friends together don't have
>> > 50,000 hours, and quite a few of them have had engine failures.
>> >
>> > I've heard the maintenance shop thing before, but you need to realize
>> > that most engine failures do not result in a major overhaul. Stuck
>> > valves and cracked jugs mean that only a single jug is replaced;
>> > failure of the carb or fuel injection system (my problem) affects only
>> > that component. And oil loss will often seize an engine and make it
>> > not worth overhauling.
>> >
>> > There are no real stats on engine failures because engine
>> > manufacturers and the FAA don't want those stats to exist. The FAA
>> > could create those stats simply by requiring pilots to report engine
>> > failures for other than fuel exhaustion/contamination reasons, but
>> > will not.
>> >
>> > The truth is, FAA certification requirements have frozen aircraft
>> > piston engines in the past, and now they're less reliable than
>> > automotive engines (not to mention ridiculously expensive).
>> >
>> > Michael

Rich Stowell

November 26th 03, 07:02 PM

(Michael) wrote in message >...
> (Rich Stowell) wrote
> > Sorry I can't point you to the "harder" data you're looking for, but
> > here's perhaps a little perspective on the issue:
> >
> > According to one NTSB Study, pilots with fewer than either 500 hours
> > total time, or 100 hours in type, are more likely to encounter an
> > inadvertent stall/spin than to have a genuine engine failure (i.e.: a
> > random-event engine failure, not one attributed to such pilot errors
> > as fuel mismanagement).
>
> Really? If that were true, then there would be hard data.

Yes, really -- see "A Study of Light Plane Stall Avoidance and
Suppression." By D.R. Ellis, Report No. FAA-RD-77-25, 1977, p. 6. As
for the "hard data" behind this finding, that's for you to follow up
on since this is your research project ;)

> What the NTSB study REALLY says is that these low time pilots are more
> likely to encounter an inadvertent stall/spin LEADING TO AN ACCIDENT
> than to have a genuine engine failure LEADING TO AN ACCIDENT.

True, but that's stating the obvious since NTSB only gets involved in,
and thus only reports on, those encounters that have led to actual
accidents.

>This is
> because an engine failure rarely leads to an accident (at least if the
> ones known to me are any indication) but an inadvertent stall/spin
> usually leads to an accident.

Define "rarely." From an industrial accident prevention standpoint,
the theoretical ratio 1:30:300 is often applied wherein for every 331
hazardous encounters of a similar type, only one will progress as far
as an actual accident (significant damage and/or injury). The rest
fall under "incidents" and "hazards."

In other words, typically 1 out of 331 encounters of a similar type
results in an accident, whether it's precipitated by an engine failure
or an inadvertent stall/spin. In the case of NTSB data, one could
extrapolate to get a feel for the order of magnitude of problems
pilots deal with in a particular category by multiplying the number of
accidents by 331.

While it is true that one accident classification may be more
prevalent than another (e.g.: more stall/spin fatalities than ground
loop fatalities), the ratio of accidents-to-total encounters may very
well be equal. In that case, 1 out of 331 would be the same for engine
failures leading to accidents as for stall/spins leading to accidents,
or any other accident type. I guess one could argue that 1 accident
out of every 331 hazardous encounters is "rare" regardless of the
cause. In that context, one could then argue that compared to the
total number of stall/spin encounters, stall/spin accidents are
equally as "rare" as engine failure accidents.

> For that matter, most engine failure fatalities in light singles are
> not the result of collision with terrain (which is usually survivable)
> but of failure to maintain flying speed (which usually isn't). That's
> basically a stall/spin anyway.

Two things: First, approximately 19 percent of stall/spin accidents
are preceded by an engine failure. But the primary accident cause is
still listed as "stall/spin." See "General Aviation Pilot Stall
Awareness Training Study," by William C. Hoffman and Walter M.
Hollister, Report No. FAA-RD-77-26, 1976, p. 6.

Second, the contention that "failure to maintain flying speed" is
"basically a stall/spin anyway" is pure myth. Spins are the result of
two ingredients that must coexist: yaw and stall. And neither yaw nor
stall is a function of airspeed. Up to the point where the wings
decide to bend or break, stalls and spins can and do occur at any
airspeed, and in any attitude.

For example, stall while at 1-g and Vso and give it some yaw = spin;
stall at 1.95 times Vso with +3.8-g's (that's the same as saying "Va
and the design limit in the Normal Category") and give it some yaw =
spin; give any airplane the right amount of g's at a given airspeed
and give it some yaw = spin.

In my experience, and based on the research I've read, I'd postulate
that the majority of stall/spin accidents occur with the airplane
operating somewhere between 1.07 to 1.20 times Vso and 1.15 to 1.41-g.
In other words, with pilots pulling into an uncoordinated, accelerated
stall while turning at bank angles between 30 and 45 degrees.

Rich
http://www.richstowell.com

Kyler Laird

November 26th 03, 07:18 PM

(Captain Wubba) writes:

>So what is it? If the engine-failure rate is one failure for every
>50,000 flight hours, I'll feel much less reticent about night/IFR
>single-engine flying than if it is one in 10,000 hours. Anybody have
>any facts or hard data, or have any idea where I might be able to
>track some down?

Don't forget that you're safest with a single-cylinder engine. If
you have a six-cylinder, you're *six* times as likely to have a
failure.

....or at least that's what I've learned from some of the geniuses
who talk about twins vs. singles.

--kyler

Peter Duniho

November 26th 03, 08:04 PM

"Kyler Laird" > wrote in message
...
> Don't forget that you're safest with a single-cylinder engine. If
> you have a six-cylinder, you're *six* times as likely to have a
> failure.

If the only thing that could go wrong with an engine was some sort of
failure of the cylinder, then that would actually be a pretty close
approximation of the truth. And in fact, if you have a six-cylinder engine,
you ARE (about) six times as likely to have a failure *of a cylinder* as you
would with a single-cylinder engine.

In the single vs. twin analysis, you have nearly double the chance of an
engine failure as with a single, all else being equal. If X (a number
between 0 and 1) is the chance of an engine failure for a single engine,
it's not that you have 2 * X chance of an engine failure for two engines.
You actually have 1 - ((1-X) * (1-X)) chance of an engine failure. But when
X is small (as it is in this case), the square of 1-X is pretty close to 1 -
(2 * X).

If all that could fail on an engine was a cylinder, or component related to
a cylinder, then a six-cylinder engine would be 1 - ((1-X) ^ 6) likely to
fail, where X is the chance of failure for a single-cylinder engine. But
just as 1 - ((1-X) ^ 2) is very close to 2 * X for small X, so too 1 -
((1-X) ^ 6) *is* actually very close to 6 * X for small X.

Now, with that essay out of the way, the real reason that six cylinder
engines aren't six times as likely to fail is that a number of failure modes
have nothing to do with the cylinder. They involve one or more other parts,
parts which exist in the same number regardless of the number of cylinders.

Note also that just as having two engines provides a benefit to offset the
very real increased opportunity for failure, having four, six, or more
cylinders provides a benefit to offset the very real increased opportunity
for *cylinder failure*. That is, with a six cylinder engine, if something
that IS specific to a cylinder fails, often the result is simply reduced
power, not a complete power failure.

> ...or at least that's what I've learned from some of the geniuses
> who talk about twins vs. singles.

Sounds like you've got some good geniuses advising you. Stick with them.

Pete

Kyler Laird

November 26th 03, 08:08 PM

"Mike Rapoport" > writes:

>> Knowing *NOTHING* about turbocharged engines, I was wondering. Would a loss
>> of the turbocharger still allow the engine to produce the same power as a
>> non-turbo engine of the same size at the same altitude? From the

>It depends on the type of turbo failure. The typical failure is the bearing
>in which case the engine will not make much, if any power.

It apparently depends on the system too. For my plane, it's recommended
to shut off the turbos for takeoff below 1000'. I've also flown quite a
few hours with blown turbo bearings, so I think it's safe to say it does
not cause a huge decrease in power.

--kyler

Kyler Laird

November 26th 03, 08:08 PM

"Peter Duniho" > writes:

>> [...] I have seen and heard of too many oil leaks, fuel
>> leaks, rubbing tubes and various parts coming loose or falling off...all
>> caused by "maitenance".

>Well, granted, the engines on your plane require a much more specialized
>maintenance crew than the one Lycoming on mine. But in spite of the very
>real possibility of human error during maintenance, as far as I know more
>engine failures are prevented by maintenance than are caused by it. I would
>be very surprised if you could find statistics to the contrary.

I'm a Lycoming-running statistic (n=1). I "lost" an engine because the
throttle cable came off months after the engine was replaced at annual.
Fortunately I noticed it on the runup. But it happened the night before
when I was dodging lightning on the approach to Durango. (I didn't notice
it then because I rolled in just ahead of the hail and was more interested
in getting under cover than parking perfectly.)

I have way too many examples of mechanics screwing up my plane.

--kyler

Morgans

November 26th 03, 08:23 PM

"Kyler Laird" > wrote in message
...
> (Captain Wubba) writes:
>
> >So what is it? If the engine-failure rate is one failure for every
> >50,000 flight hours, I'll feel much less reticent about night/IFR
> >single-engine flying than if it is one in 10,000 hours. Anybody have
> >any facts or hard data, or have any idea where I might be able to
> >track some down?
>
> Don't forget that you're safest with a single-cylinder engine. If
> you have a six-cylinder, you're *six* times as likely to have a
> failure.
>
> ...or at least that's what I've learned from some of the geniuses
> who talk about twins vs. singles.

Not so, smart ass. You don't have six oil pumps, six crank seals, six fuel
pumps, six alternators, six crankshafts, 12 magnetos, 6 carbs, ect, ect, on
that six cylinder engine, do you?
--
Jim in NC

Peter Duniho

November 26th 03, 08:36 PM

"Kyler Laird" > wrote in message
...
> I'm a Lycoming-running statistic (n=1). I "lost" an engine because the
> throttle cable came off months after the engine was replaced at annual.
> Fortunately I noticed it on the runup.

An engine failure on the ground isn't an engine failure. :)

Seriously though, that's the whole point of preflight inspections and
runups. The only question here is what's more likely to cause an
*in-flight* engine failure. Is it maintenance? Or lack of maintenance?

I too have had a variety of "failures" (engine-related and otherwise), some
of which were a direct result of work done on the airplane. Fortunately,
none happened in flight. But the fact that a mechanic is falliable does not
mean that the engine is better off without the mechanic.

If any of you "mechanics are bad for my airplane!" folks actually have some
hard numbers to show that airplanes not given any maintenance are more
reliable than airplanes that have received maintenance, by all means, show
it (I don't believe you can). Otherwise, you are taking a cute joke WAY too
far.

Pete

Michael

November 26th 03, 08:52 PM

David Megginson > wrote
> I'm curious where the statistics are that show that most pilots cannot
> handle an AI failure in IMC. This FAA report
>
> http://www1.faa.gov/fsdo/orl/files/advcir/P874052.TXT
>
> states that vacuum failures are a factor in an average of 2 accidents per
> year, and that there is an average of one vacuum-related accident for every
> 40,000 to 50,000 GA IFR flight plans filed. That doesn't tell us much,
> though, since we don't know how many non-fatal vacuum failures occurred
> during those flights.

I have about 700 hours flying behind a dry pump, and one catastrophic
failure. I also have about 1400 hours flying planes with gyros (some
of my time is in gliders and no-gyro taildraggers) and at least three
gyro failures. I have to believe that vacuum or gyro failure occurs
AT LEAST once every 1000 hours.

Assuming that the average GA IFR flight plan leads to 30 minutes of
IMC (I know a lot of them are filed procedurally so I'm being
pessimistic) that still sounds like 1 accident in 20,000 hours. So it
sounds to me like 95%+ of the pilots who experience vacuum or gyro
failure are handling it without an accident.

From what I've seen of GA IFR pilots, at most 10% are getting
recurrent training in partial panel operations to PTS standards.

Michael

David Megginson

November 26th 03, 10:25 PM

jim rosinski wrote:

> Well, for those of us less studly than this, I'd still take an engine
> failure over gyro failure in IMC under most conditions. Maybe given
> the time/money to train "properly" gyro failure isn't such a major
> emergency. But I don't have either the time or the money, so this
> instrument-rated pilot isn't flying IFR till he gets a plane with
> backup gyros or electric AI.

Yow! I hope that you mean an engine failure in fairly high IMC (i.e. the
ceiling well above terrain and obstacles). Compared to a forced landing
with, say, a 300 ft ceiling in an area with lots of hills and towers, flying
in IMC with the TC and mag compass sounds like a walk in the park.

The FAA report I quoted earlier in this thread stated an interesting fact --
all of the GA fatalities during their study period due to vacuum failure
were in high-performance planes with retractable gear. Nobody was spiraling
in a 182 or Cherokee Six after a vacuum failure in IMC, much less a Skyhawk
or Cherokee. I'm sure that they do happen, but they must not be so common.

That suggests to me that in the unlikely event I ever can afford a
high-performance retractable, the first action in event of lost gyros should
be to lower the gear, airspeed be damned.

All the best,

David

David Megginson

November 26th 03, 10:33 PM

Michael wrote:

>> http://www1.faa.gov/fsdo/orl/files/advcir/P874052.TXT

> Assuming that the average GA IFR flight plan leads to 30 minutes of
> IMC (I know a lot of them are filed procedurally so I'm being
> pessimistic) that still sounds like 1 accident in 20,000 hours. So it
> sounds to me like 95%+ of the pilots who experience vacuum or gyro
> failure are handling it without an accident.

That sounds pretty reasonable. As I just mentioned in another posting, the
report also mentions that all of the fatal GA accidents from vacuum failures
in their study period happened in high-performance aircraft with retractable
gear.

> From what I've seen of GA IFR pilots, at most 10% are getting
> recurrent training in partial panel operations to PTS standards.

In Canada, partial panel is not even part of the IFR flight test (though we
do learn it during training). On the other hand, we have to retake our
entire flight test every two years, and the examiner can always fail
something (including the AI) if he/she wants to. The other benefit is that
without the partial panel and unusual-attitude recovery, we can take our
flight tests in actual IMC, as I did.

All the best,

David

Michael

November 26th 03, 10:48 PM

(Rich Stowell) wrote
> > Really? If that were true, then there would be hard data.
> Yes, really

No, not really. No hard numbers on actual engine failures (or
stall-spins for that matter) - only the ones that led to an NTSB
reported accident.

> True, but that's stating the obvious since NTSB only gets involved in,
> and thus only reports on, those encounters that have led to actual
> accidents.

But this hideously skews the picture. The only way the events are
comparable is if the probability of an engine failure leading to an
accident is approximately equivalent to the probability of a
stall-spin leading to an accident. This is exactly what I am
disputing.

> Define "rarely." From an industrial accident prevention standpoint,
> the theoretical ratio 1:30:300 is often applied wherein for every 331
> hazardous encounters of a similar type, only one will progress as far
> as an actual accident (significant damage and/or injury). The rest
> fall under "incidents" and "hazards."

That ratio is nothing more than an expression of ignorance. In
reality, depnding on the hazard the numbers can be very different.

Industrial safety types love to quote statistics like this to scare
people, but in reality there is usually a reason why some hazardous
encounters lead to accidents or incidents while most do not. It's not
random. These reasons generally have to do with individual skill,
knowledge, and experience as well as factors the industrial safety
people are never told because they involve routine violations of
safety rules. Often the same dynamic plays out in NTSB
investigations.

> In other words, typically 1 out of 331 encounters of a similar type
> results in an accident, whether it's precipitated by an engine failure
> or an inadvertent stall/spin.

No, this is total nonsense because stall-spins and engine failures are
not similar. First of all, a mechanical failure generally occurs in a
manner that is beyond the pilot's control. When the main seal blows
out, or the engine swallows a valve, or a rod goes through a cylinder,
or the fuel injectors clog with rust - that's almost always completely
independent of pilot skill, knowledge, and judgment. On the other
hand, an inadvertent stall-spin is caused by the pilot. Therefore,
we're not even looking at the same population.

Just by virtue of the fact that the pilot allowed the inadvertent
stall-spin situation to develop, we can expect that he is less likely
to handle it properly. The same is not true of engine failure.

> In the case of NTSB data, one could
> extrapolate to get a feel for the order of magnitude of problems
> pilots deal with in a particular category by multiplying the number of
> accidents by 331.

This is absolutely ridiculous. In addition to the issue of hazard
exposure (mechanical engine failures don't discriminate but
stall-spins do) there is also the issue of hazard magnitude. Off
field landings in gliders, for example, are VERY rarely fatal. The
ratio there is 5000:1. On the other hand, I would be amazed if the
fatality ratio for midairs was much better than 3:1. 331 may be a
good all-around average in aviation (or it may not - data are not
available) but to apply it indiscriminately to all types of hazards
makes no sense at all.

> > For that matter, most engine failure fatalities in light singles are
> > not the result of collision with terrain (which is usually survivable)
> > but of failure to maintain flying speed (which usually isn't). That's
> > basically a stall/spin anyway.
>
> Two things: First, approximately 19 percent of stall/spin accidents
> are preceded by an engine failure. But the primary accident cause is
> still listed as "stall/spin."

There is one school of thought that considers this proper. Just
because engine power is lost is no excuse to stall and spin. Gliders
don't even have engines. However, that doesn't change the fact that
had the engine kept running, the stall-spin would likely not have
happened.

> Second, the contention that "failure to maintain flying speed" is
> "basically a stall/spin anyway" is pure myth. Spins are the result of
> two ingredients that must coexist: yaw and stall. And neither yaw nor
> stall is a function of airspeed. Up to the point where the wings
> decide to bend or break, stalls and spins can and do occur at any
> airspeed, and in any attitude.

That's all great, but the reality is that in normal flight (not
involving aerobatics or other abrupt maneuvering) stall avoidance is
all about keeping your airspeed up. Those 19% of stall-spins caused
by engine failure are the result of trying to stretch the glide or
maneuvering to make a landing area, and likely both.

> In my experience, and based on the research I've read, I'd postulate
> that the majority of stall/spin accidents occur with the airplane
> operating somewhere between 1.07 to 1.20 times Vso and 1.15 to 1.41-g.
> In other words, with pilots pulling into an uncoordinated, accelerated
> stall while turning at bank angles between 30 and 45 degrees.

That's great, but had those pilots maintained at least 1.3 Vso for
these maneuvers, they would not have stalled. Thus saying airspeed is
irrelevant is technically correct but not particularly useful.

Yes, you can stall at any airspeed in any attitude. I've stalled at
100+ kts (in a plane which normally stalled at 60 kts), full power,
and the nose 80 degrees below the horizon - as an aerobatic instructor
I'm sure you know exactly what I did wrong to make that happen. That
doesn't change the reality - in an engine-out situation, the
stall-spin is caused by a failure to maintain flying speed.

Michael

Kyler Laird

November 27th 03, 12:08 AM

"Morgans" > writes:

>> Don't forget that you're safest with a single-cylinder engine. If
>> you have a six-cylinder, you're *six* times as likely to have a
>> failure.
>>
>> ...or at least that's what I've learned from some of the geniuses
>> who talk about twins vs. singles.

>Not so, smart ass. You don't have six oil pumps, six crank seals, six fuel
>pumps, six alternators, six crankshafts, 12 magnetos, 6 carbs, ect, ect, on
>that six cylinder engine, do you?

Correct, genius. Similarly, there are engine problems that are quite
independent of the number of engines on a plane.

--kyler

Kyler Laird

November 27th 03, 12:08 AM

"Peter Duniho" > writes:

>"Kyler Laird" > wrote in message
...
>> I'm a Lycoming-running statistic (n=1). I "lost" an engine because the
>> throttle cable came off months after the engine was replaced at annual.
>> Fortunately I noticed it on the runup.

>An engine failure on the ground isn't an engine failure. :)

Like I said, I lost it in flight. I noticed it on the ground.

--kyler

Peter Duniho

November 27th 03, 12:28 AM

"Kyler Laird" > wrote in message
...
> Like I said, I lost it in flight. I noticed it on the ground.

I think you're missing the point (even ignoring the apparent inconsistencies
in the event you're trying to describe).

Pete

Peter Duniho

November 27th 03, 12:30 AM

"Kyler Laird" > wrote in message
...
> Correct, genius. Similarly, there are engine problems that are quite
> independent of the number of engines on a plane.

Such as? Other than fuel exhaustion, I'm at a loss to think of any.

Rich Stowell

November 27th 03, 12:43 AM

Thanks for that, Big John,

I recall seeing similar stats -- I'll have to dig around in my files
to find the context and the reason for that second spike at 1,000
hours ... so much to do!

I posted a follow-up to Michaels response to my post as well.

Rich
http://www.richstowell.com

Big John > wrote in message >...
> Rich
>
> Some other data to put in the pot.
>
> The Air Force paid some one (Rand Corporation or some other think
> tank) to do a study on accidents vs flying time.
>
> It basically came out that there were two spikes, one around 500 hours
> and the other around 1000 hours. The 500 hour accidents were
> attributed to cocky over confidence. Not sure right now what the 1000
> spike was but it was caused by something we could train around or
> change procedures, etc. to reduce as I recall.
>
> Big John
>
>
>
> On 25 Nov 2003 07:57:26 -0800, (Rich Stowell)
> wrote:
>
> >Sorry I can't point you to the "harder" data you're looking for, but
> >here's perhaps a little perspective on the issue:
> >
> >According to one NTSB Study, pilots with fewer than either 500 hours
> >total time, or 100 hours in type, are more likely to encounter an
> >inadvertent stall/spin than to have a genuine engine failure (i.e.: a
> >random-event engine failure, not one attributed to such pilot errors
> >as fuel mismanagement).
> >
> >
> >In my case, over 6,400 hours with 5,600+ hours of instruction given
> >(mostly doing spin, emergency maneuver, aerobatic, and tailwheel
> >training -- the type of flying that might be considered harder on an
> >engine than more routine types of flying), I've had several
> >non-critical engine anomalies that were successfully dealt with,
> >including:
> >
> >Prop stoppages during spins due to a couple of students hanging on so
> >tight to the throttle that it choked off the engine -- we call that
> >"fright idle";
> >
> >Clogged fuel injectors during take-off that only revealed themselves
> >at full throttle;
> >
> >Primer controls that were not truly "in and locked" which has lead to
> >prop stoppages during idle power landings.
> >
> >
> >In addition, two legitimate engine failures as follows:
> >
> >The first, a fuel injector failure as we entered the traffic pattern
> >(after practicing off field landings, no less!) -- landed without
> >further incident;
> >
> >The second, carb ice in a Champ during a flight review choked off the
> >engine during a touch and go -- touched down on the taxiway abeam the
> >departure end of the runway, hit a parked Porshe, bent the airplane,
> >walked away without so much as a scratch.
> >
> >Rich
> >http://www.richstowell.com
> >
> >
> >
> (Captain Wubba) wrote in message >...
> >> Indeed. Interesting. But I'd still like to see some hard data. This is
> >> the kind of problem I run into...most of your pilot friends report
> >> that they have had a failure, but the majority of mine report none.
> >> And none of the 2000+ hour CFI types I asked (I asked 4 of them) have
> >> ever experienced an engine failure. My dad was a pilot with well over
> >> 12,000 hours and never had one. Another relative had fewer than 500
> >> hours total in his flying carrer and lost one on his first solo XC.
> >>
> >> I asked another A&P I ran into at the airport tonight, and he said he
> >> thought it should be at least 40,000 hours per in-flight engine
> >> failure, but really wasn't sure. Since a big part of flying is risk
> >> management, it would be very helpful to *really* know the risks
> >> involved. If the odds of losing an engine are 1 in 50,000 hours, then
> >> night/hard-IFR single-engine flying becomes a great deal more
> >> appealing than if it is 1 in 10,000 hours.
> >>
> >> I'll try to go over the NTSB data more thoroughly, I think a
> >> reasonable extrapolation would be that at least 1 in 4 in-flight
> >> engine failures (probably more) would end up in the NTSB database.
> >> But the cursory review I made earlier made me think the numbers were
> >> much less negative than I had considered before. And the opinions of
> >> these A&Ps are very interesting, because while failure might not
> >> require a total overhaul, it will require *something* to be done by a
> >> mechanic...and if these guys are seeing 30-40 engines make it to TBO
> >> for every one needing repair due to an in-flight failure, that might
> >> well support the 40,000 to 50,000 hour hypothesis.
> >>
> >> Cheers,
> >>
> >> Cap
> >>
> >>
> >> (Michael) wrote in message >...
> >> > (Captain Wubba) wrote
> >> > > Howdy. I was discussing with a friend of mine my concerns about flying
> >> > > single-engine planes at night or in hard IFR, due to the possibility
> >> > > of engine failure. My buddy is a CFI/CFII/ATP as well as an A&P, about
> >> > > 3500 hours, and been around airplanes for a long time, so I tend to
> >> > > give credence to his experiences. He asked me how often I thought a
> >> > > piston engine had an in-flight engine failure. I guestimated once
> >> > > every 10,000 hours or so. He said that was *dramatically*
> >> > > over-estimating the failure rate. He said that in his experience it is
> >> > > at least 40,000 to 50,000 hours per in-flight engine failure.
> >> >
> >> > The only vaguely official number that I've ever seen came from a UK
> >> > accident report for a US-built twin. The UK investigators queried the
> >> > FAA on engine failure rates for the relevant engine, and the only
> >> > answer they got was that piston engines have failure rates on the
> >> > order of 1 in 1000 to 1 in 10000 hours. This is consistent with my
> >> > experience. I've had one non-fuel-related engine failure (partial,
> >> > but engine could only produce 20-30% power) in 1600+ hrs. Most people
> >> > I know with over 1500 GA hours have had an engine failure.
> >> >
> >> > 50,000 hours is not realistic. Excluding a few airline pilots (who
> >> > have ALL had engine failures) all my pilot friends together don't have
> >> > 50,000 hours, and quite a few of them have had engine failures.
> >> >
> >> > I've heard the maintenance shop thing before, but you need to realize
> >> > that most engine failures do not result in a major overhaul. Stuck
> >> > valves and cracked jugs mean that only a single jug is replaced;
> >> > failure of the carb or fuel injection system (my problem) affects only
> >> > that component. And oil loss will often seize an engine and make it
> >> > not worth overhauling.
> >> >
> >> > There are no real stats on engine failures because engine
> >> > manufacturers and the FAA don't want those stats to exist. The FAA
> >> > could create those stats simply by requiring pilots to report engine
> >> > failures for other than fuel exhaustion/contamination reasons, but
> >> > will not.
> >> >
> >> > The truth is, FAA certification requirements have frozen aircraft
> >> > piston engines in the past, and now they're less reliable than
> >> > automotive engines (not to mention ridiculously expensive).
> >> >
> >> > Michael

G.R. Patterson III

November 27th 03, 01:28 AM

Big John wrote:
>
> It basically came out that there were two spikes, one around 500 hours
> and the other around 1000 hours. The 500 hour accidents were
> attributed to cocky over confidence.

I read the same thing about ten years ago. As I recall, the 1000 hour spike was
also tentatively attributed to overconfidence.

George Patterson
A man who carries a cat by the tail learns something that can be learned
no other way.

[email protected]

November 27th 03, 02:37 AM

On 24 Nov 2003 11:31:57 -0800, (Captain Wubba)
wrote:

snip

>So what is it? If the engine-failure rate is one failure for every
>50,000 flight hours, I'll feel much less reticent about night/IFR
>single-engine flying than if it is one in 10,000 hours. Anybody have
>any facts or hard data, or have any idea where I might be able to
>track some down?

snip

No hard facts, only "remembered" incidents, definitely not scientific,
sorry.

Engine failures/inflight shutdowns that I've "seen" as a licensed
technician in the last 20 years:

Beech "Super" 18-cylinder hold-down stud/crankcase failure x 2.

Beech "Super" 18-connecting rod failure.

Beech "Super" 18-cylinder barrel/head separation.

Beech "Super" 18-intake valve ingestion x 2.

Beech "Super" 18-crankshaft failure/prop departure (on TO, so
technically not an in-flight).

T-arrow-broken non-standard tee fitting to oil pressure (hourmeter)
switch, oil fire.

Archer-fuel bowl bail popped off x 3.

Cherokee 180-accessory gear driving camshaft split in half.

Navajo Chieftain-cam fell off of fresh overhauled single drive (and
cam) "dual" magneto. Pilot/mechanic (not me) that installed it was
driving it when it crapped.

Navajo Chieftain-turbocharger grenaded, oil fire (fresh turbo
overhaul).

Navajo Chieftain-turbo supply line left loose after maintenance (that
one would be my fault).

Navajo Chieftain-cylinder hold-down stud/crankcase failure.

Navajo Chieftain-severe detonation, eventual oil exhaustion.

Cherokee Six-fuel exhaustion.

Warrior-fuel exhaustion.

J-3 Cub-carb ice.

SWAG of total operating hours +-200000.

The Twin Beech figures are due to the extreme age/unknown-high cycle
time of engines/cylinders.

The Chieftain crankcase failure was on a previously repaired
crankcase.

I think of any more, I'll add 'em to the list.

TC

Rich Stowell

November 27th 03, 03:41 AM

Geez Michael, settle down! So much stress in the cockpit cannot be
conducive to learning or safety...

(Michael) wrote in message >...
> (Rich Stowell) wrote
> > > Really? If that were true, then there would be hard data.
> > Yes, really
>
> No, not really. No hard numbers on actual engine failures (or
> stall-spins for that matter) - only the ones that led to an NTSB
> reported accident.

Interesting that I cited a specific source for my statement, which you
summarily ignore as either irrelevant or incapable of leading to
numbers that might be relevant to the concerns that started this post.
Have you read the study I cited? Have you followed up on the
references cited in that study to see where it might lead in the quest
for hard numbers on this issue? Or is it easier to just tell everyone
else that they're idiots rather than trying to make a serious
contribution to the discussion?

> > True, but that's stating the obvious since NTSB only gets involved in,
> > and thus only reports on, those encounters that have led to actual
> > accidents.
>
> But this hideously skews the picture. The only way the events are
> comparable is if the probability of an engine failure leading to an
> accident is approximately equivalent to the probability of a
> stall-spin leading to an accident. This is exactly what I am
> disputing.

If it "hideously skews the picture" wouldn't that apply to all
accident numbers from NTSB? Each stall/spin accident represent the tip
of the stall/spin problem. Each engine failure accident represents the
tip of the engine failure scenario. Accident stats are a poor measure
of our overall stall/spin awareness, and of our ability to cope with
engine failures precisely because accident numbers represent the
relatively few pilots who have had an accident. But useful information
can be gleaned. Insight into the broader problems might be found as
well. And yes, some kind of logical extrapolation may then be possible
to assess the overall magnitude of the issue.

> > Define "rarely." From an industrial accident prevention standpoint,
> > the theoretical ratio 1:30:300 is often applied wherein for every 331
> > hazardous encounters of a similar type, only one will progress as far
> > as an actual accident (significant damage and/or injury). The rest
> > fall under "incidents" and "hazards."
>
> That ratio is nothing more than an expression of ignorance. In
> reality, depnding on the hazard the numbers can be very different.

You neglected to define "rarely." And which "numbers" can be very
different -- total numbers, ratios, what? Granted, total raw numbers
can be significantly different between different accident types,
but--as the study of industrial accident prevention postulates--they
may be linked by comparable ratios or some other normalizing
parameter.

> Industrial safety types love to quote statistics like this to scare
> people, but in reality there is usually a reason why some hazardous
> encounters lead to accidents or incidents while most do not. It's not
> random. These reasons generally have to do with individual skill,
> knowledge, and experience as well as factors the industrial safety
> people are never told because they involve routine violations of
> safety rules. Often the same dynamic plays out in NTSB
> investigations.

The intent was not to scare anyone, but to try to add some perspective
tying the comparatively rare accident to the unknown (perhaps
unknowable) number of hazardous situations that are dealt with without
further incident. And yes, there are always reasons why aviation
accidents happen, be it attributable to Software (checklists, SOP's,
etc.), Hardware (airplane, systems, cockpit layout, etc.), Liveware
(the pilot, pax, ATC, etc.), Environment, or the interaction of some
or all of these.

> > In other words, typically 1 out of 331 encounters of a similar type
> > results in an accident, whether it's precipitated by an engine failure
> > or an inadvertent stall/spin.
>
> No, this is total nonsense because stall-spins and engine failures are
> not similar. First of all, a mechanical failure generally occurs in a
> manner that is beyond the pilot's control. When the main seal blows
> out, or the engine swallows a valve, or a rod goes through a cylinder,
> or the fuel injectors clog with rust - that's almost always completely
> independent of pilot skill, knowledge, and judgment. On the other
> hand, an inadvertent stall-spin is caused by the pilot. Therefore,
> we're not even looking at the same population.

OK, Michael knows best, everyone else is an idiot. The point of the
pyramidal accident ratio is not to compare engine failures with
stall/spins. Yes, they are two dissimilar accident types in terms of
the driving mechanisms -- the engine in one case vs. the pilot in the
other. But that does not preclude the mix of accidents, hazards, and
incidents within each population from sharing a common relationship.

From that standpoint, so what if a hole is blown through the crankcase
and the windscreen gets covered with oil, obscuring the pilot's
ability to see well enough to land under control. The airplane still
gets busted and it's still labelled an engine failure accident.
Likewise, so what if the pilot skids a turn and causes the airplane
to spin into the ground. It's still a stall/spin accident. But for
each one of those accidents, there are many more pilots who, with an
oil-slicked windscreen, were able to land under control; there are
many more pilots who recognized the developing skid, corrected it, and
continued under control. The industrial accident maxim only attempts
to quantify how many within each group were able to avert the
accident.

You can disagree with the theory or its application (in which case, it
would be beneficial to put forth an alternative), but can't you do it
without denigrating? This is supposed to be a forum for learning -- is
this how you treat your students?

> Just by virtue of the fact that the pilot allowed the inadvertent
> stall-spin situation to develop, we can expect that he is less likely
> to handle it properly. The same is not true of engine failure.

I would disagree thusly: the pilot who does not routinely ("routinely"
meaning at least 50% of the time) simulate an engine failure followed
by a glide to landing (even from abeam the numbers would be
beneficial) is equally as likely not to be able to handle an engine
failure to a successful landing (i.e.: no accident) as a pilot who
allows the development of an inadvertent stall/spin. I would postulate
that the majority of active pilots (except maybe for students)
practice simulated engine outs far less than 50% of the time.

> > In the case of NTSB data, one could
> > extrapolate to get a feel for the order of magnitude of problems
> > pilots deal with in a particular category by multiplying the number of
> > accidents by 331.
>
> This is absolutely ridiculous. In addition to the issue of hazard
> exposure (mechanical engine failures don't discriminate but
> stall-spins do) there is also the issue of hazard magnitude. Off
> field landings in gliders, for example, are VERY rarely fatal. The
> ratio there is 5000:1. On the other hand, I would be amazed if the
> fatality ratio for midairs was much better than 3:1. 331 may be a
> good all-around average in aviation (or it may not - data are not
> available) but to apply it indiscriminately to all types of hazards
> makes no sense at all.

Be gentle, you're dealing with an idiot after all ;) Please explain
how an engine failure does not discriminate, yet stall/spin accidents
do. The typical stall/spin profile involves a typical pilot on a
typical flight -- sounds pretty indiscriminate to me.

Please cite your source for the 5000:1 ratio for gliders. Also, glider
pilots are always performing engine-out landings, so it would seem to
make sense that they'd be better at it than those of us who fly
powered airplanes.

As for mid-airs, during the period 1977-1986, 40 percent of the
mid-airs ended without injury.

As for fatality ratio -- yes, the fatality rates between accident
types is not at all equal. But for the purposes of counting accidents,
a situation in which the pilot walks away unhurt, but the airplane's
wing is torn off, is still an "accident" and is therefore equivalent
to a case where a pilot lands in a field with the only damage being a
tree branch through the windscreen, which kills the pilot. They are
both accidents per the definition of the term.

> > > For that matter, most engine failure fatalities in light singles are
> > > not the result of collision with terrain (which is usually survivable)
> > > but of failure to maintain flying speed (which usually isn't). That's
> > > basically a stall/spin anyway.
> >
> > Two things: First, approximately 19 percent of stall/spin accidents
> > are preceded by an engine failure. But the primary accident cause is
> > still listed as "stall/spin."
>
> There is one school of thought that considers this proper. Just
> because engine power is lost is no excuse to stall and spin. Gliders
> don't even have engines. However, that doesn't change the fact that
> had the engine kept running, the stall-spin would likely not have
> happened.
>
> > Second, the contention that "failure to maintain flying speed" is
> > "basically a stall/spin anyway" is pure myth. Spins are the result of
> > two ingredients that must coexist: yaw and stall. And neither yaw nor
> > stall is a function of airspeed. Up to the point where the wings
> > decide to bend or break, stalls and spins can and do occur at any
> > airspeed, and in any attitude.
>
> That's all great, but the reality is that in normal flight (not
> involving aerobatics or other abrupt maneuvering) stall avoidance is
> all about keeping your airspeed up. Those 19% of stall-spins caused
> by engine failure are the result of trying to stretch the glide or
> maneuvering to make a landing area, and likely both.
>
> > In my experience, and based on the research I've read, I'd postulate
> > that the majority of stall/spin accidents occur with the airplane
> > operating somewhere between 1.07 to 1.20 times Vso and 1.15 to 1.41-g.
> > In other words, with pilots pulling into an uncoordinated, accelerated
> > stall while turning at bank angles between 30 and 45 degrees.
>
> That's great, but had those pilots maintained at least 1.3 Vso for
> these maneuvers, they would not have stalled. Thus saying airspeed is
> irrelevant is technically correct but not particularly useful.
>
> Yes, you can stall at any airspeed in any attitude. I've stalled at
> 100+ kts (in a plane which normally stalled at 60 kts), full power,
> and the nose 80 degrees below the horizon - as an aerobatic instructor
> I'm sure you know exactly what I did wrong to make that happen. That
> doesn't change the reality - in an engine-out situation, the
> stall-spin is caused by a failure to maintain flying speed.

No -- the stall/spin is caused by yaw and stall, period. Don't yaw and
the airplane will not spin, regardless of speed. Be aware of the
relationship between g-load and airspeed trend and accidental stalls
are less likely. Continuing to tell pilots to fly faster, in order to
"maintain flyng speed," unneccessarily makes a lot of perfectly good
runways either inaccessible or dangerous to too many pilots. I've seen
only two stall/spin accidents here at my 2500-foot home airport over
the years, but I've seen many more airplanes broken because they
over-ran the runway flying fast enough to "maintain flying speed."

As educators, we can do better than that...

Rich
http://www.richstowell.com

Rich Stowell

November 27th 03, 03:41 AM

Kyler Laird

November 27th 03, 04:08 AM

"Peter Duniho" > writes:

>"Kyler Laird" > wrote in message
...
>> Correct, genius. Similarly, there are engine problems that are quite
>> independent of the number of engines on a plane.

>Such as? Other than fuel exhaustion, I'm at a loss to think of any.

Fuel exhaustion certainly accounts for a lot, but there's also
misfueling, fuel contamination, and intake clogging by widespread
particulates. All are as about likely to take out one as they are
several.

BTW, one of the things I like about a twin is the slight
difference in when such a loss is likely to happen. If one
engine runs out of fuel, runs into bad fuel, or gets socked with
ice/ash/..., at least I usually have a few seconds/minutes of power
on the other one before it experiences the same thing. It might
not seem like much, but it can be quite an advantage in sticky
situations. (Yes, yes...and if I decide to be stupid, it also
makes flipping the airplane over even easier - just like stalling a
single upon loss of power.)

--kyler

Peter Duniho

November 27th 03, 07:28 AM

"Kyler Laird" > wrote in message
...
> Fuel exhaustion certainly accounts for a lot, but there's also
> misfueling, fuel contamination, and intake clogging by widespread
> particulates.

What's "misfueling"? Sounds like fuel exhaustion to me. As for the others,
you're right to the extent that all engines are run from the same fuel
supply. Many twins have separate tanks for each engine and may or may not
suffer the same problems.

In any case, the incidence of those failures is extremely low, compared to
the total number of failures (not counting fuel exhaustion of course which,
if I recall correctly, is the number one cause of engine failures).

The fact remains, having a second engine *does* significantly increase your
chances of an engine failure, just as having extra cylinders increases your
chance of having a cylinder failure. In most cases, it's a worthwhile
tradeoff, but one shouldn't pretend the tradeoff doesn't exist.

Pete

Tom S.

November 27th 03, 07:53 AM

"Rich Stowell" > wrote in message
om...
> Thanks for that, Big John,
>
> I recall seeing similar stats -- I'll have to dig around in my files
> to find the context and the reason for that second spike at 1,000
> hours ... so much to do!

The overconfidence that comes from having "four digit experience"?

Tom -- just hit the 2,000 hour milestone...so I'm watching my ass.

G.R. Patterson III

November 27th 03, 04:47 PM

Peter Duniho wrote:
>
> "Kyler Laird" > wrote in message
> ...
> > Fuel exhaustion certainly accounts for a lot, but there's also
> > misfueling, fuel contamination, and intake clogging by widespread
> > particulates.
>
> What's "misfueling"?

Putting jet-A in a gasoline burner (or vice-versa).

George Patterson
Some people think they hear a call to the priesthood when what they really
hear is a tiny voice whispering "It's indoor work with no heavy lifting".

Peter Duniho

November 27th 03, 06:54 PM

"G.R. Patterson III" > wrote in message
...
> > What's "misfueling"?
>
> Putting jet-A in a gasoline burner (or vice-versa).

Ahh, okay. Still, quite uncommon relative to other kinds of engine failure,
especially with respect to in-flight failures.

G.R. Patterson III

November 28th 03, 01:03 AM

Peter Duniho wrote:
>
> Ahh, okay. Still, quite uncommon relative to other kinds of engine failure,
> especially with respect to in-flight failures.

It'll become a lot more common as the diesels become more common.

George Patterson
Some people think they hear a call to the priesthood when what they really
hear is a tiny voice whispering "It's indoor work with no heavy lifting".

Peter Duniho

November 28th 03, 05:09 AM

"G.R. Patterson III" > wrote in message
...
> It'll become a lot more common as the diesels become more common.

Could be. We'll see. I suspect it won't be as big a problem as you think.
For sure, some lineboy is going to screw up at some point, but I think the
increased risk of confusion will be mostly mitigated by the fact that owners
of diesel-powered aircraft will be VERY sensitive to the issue and will go
to great lengths to avoid the problem as best they can.

In any case, that time isn't here yet. Even if it does come, I suspect that
we will not see a significant increase in in-flight engine failures as a
result.

Pete

Kyler Laird

November 28th 03, 06:09 AM

"Peter Duniho" > writes:

>"Kyler Laird" > wrote in message
...
>> Fuel exhaustion certainly accounts for a lot, but there's also
>> misfueling, fuel contamination, and intake clogging by widespread
>> particulates.

>What's "misfueling"?

I was thinking of getting a fuel that will not burn effectively in
the plane's engine(s)

>Sounds like fuel exhaustion to me.

I welcome suggestions on how I could have stated it more clearly.

>As for the others,
>you're right to the extent that all engines are run from the same fuel
>supply.

Packing ice/ash/... into the _air_ intake has little to do with the
fuel supply. (Again, I think I was not clear.)

>Many twins have separate tanks for each engine and may or may not
>suffer the same problems.

If the lineman fuels the plane from the wrong (Jet A) truck, it's
unlikely to matter which tanks feed which engines unless you did
not fill all of the tanks.

>In any case, the incidence of those failures is extremely low,

Great. I don't need to worry about all of those stories I heard of
getting JetA in an airplane marked "Turbo." Thanks.

>The fact remains, having a second engine *does* significantly increase your
>chances of an engine failure, just as having extra cylinders increases your
>chance of having a cylinder failure. In most cases, it's a worthwhile
>tradeoff, but one shouldn't pretend the tradeoff doesn't exist.

Agreed. I don't think anyone pretends the tradeoff doesn't exist.
Some do pretend that it is a linear relationship thus ignoring what
you describe as the most popular failures (along with the others
that I listed).

--kyler

Peter Duniho

November 28th 03, 06:34 AM

"Kyler Laird" > wrote in message
...
> >Sounds like fuel exhaustion to me.
>
> I welcome suggestions on how I could have stated it more clearly.

Sorry, can't help you there. The screw up was mine.

> Packing ice/ash/... into the _air_ intake has little to do with the
> fuel supply. (Again, I think I was not clear.)

I don't consider that a "failure" any more than I consider flying into the
side of a mountain a structural failure. Particulates dense enough to shut
down an engine are dense enough that the pilot had no business flying into
them in the first place (or was unfortunate enough to be overtaken by a
cloud).

> >In any case, the incidence of those failures is extremely low,
>
> Great. I don't need to worry about all of those stories I heard of
> getting JetA in an airplane marked "Turbo." Thanks.

I'd hazard a guess that you don't. I've owned my turbocharged aircraft for
nearly ten years now, and have NEVER had any sort of confusion regarding
what kind of fuel it takes. The filler holes are clearly marked 100LL, I
supervise all fueling, and in any case, *real* turbine aircraft don't have
"turbo" written on the side.

I've heard those same stories, but have never seen any evidence that they
were anything more than apocryphal. I can believe it might have happened
once or twice, but it hardly sounds like something that happens often enough
to skew engine failure statistics, especially when one is only considering
in-flight engine failures.

> Agreed. I don't think anyone pretends the tradeoff doesn't exist.
> Some do pretend that it is a linear relationship thus ignoring what
> you describe as the most popular failures (along with the others
> that I listed).

Well, even ignoring the factors you've mentioned, it's not actually a linear
relationship. It's just *nearly* linear, near enough that the
generalization is reasonably true. The other factors that you've mentioned
don't really change that relationship, IMHO. It's still *nearly* true, just
as it is without considering them.

Bottom line: the more stuff you have, the more likely something will go
wrong with some of your stuff. :)

Pete

Craig Prouse

November 28th 03, 06:41 AM

"Peter Duniho" wrote:

> The filler holes are clearly marked 100LL

Aren't the filler holes restricted to prevent entry of a standard size Jet A
nozzle? I could swear USAIG was offering me some inducement to install such
restrictors, except that they're already standard on my aircraft.

Peter Duniho

November 28th 03, 08:55 AM

"Craig Prouse" > wrote in message
...
> > The filler holes are clearly marked 100LL
>
> Aren't the filler holes restricted to prevent entry of a standard size Jet
A
> nozzle?

Perhaps they could be. I don't know. I've never tried to put a Jet A
nozzle in any of the filler holes on my airplane. I don't even know what
one looks like.

I *can* say that the filler holes on my airplane are a LOT larger than the
usual 100LL nozzle and they don't have any special restrictor built in.

Pete

Doug Carter

November 28th 03, 02:07 PM

"Peter Duniho" > wrote in message >...
> "G.R. Patterson III" > wrote in message
> ...
> > It'll become a lot more common as the diesels become more common.
>
> Could be. We'll see. I suspect it won't be as big a problem as you think.
> For sure, some lineboy is going to screw up at some point,

Good reason to fuel the airplane yourself. If nothing else this gives
you a double check to make sure it is really fuled. It may be
impractical to supervise the bolting on the cylinders but you can the
fuel and (lack of) fuel is a lot more likely to be a problem.

Kyler Laird

November 28th 03, 02:09 PM

"Peter Duniho" > writes:

>> Packing ice/ash/... into the _air_ intake has little to do with the
>> fuel supply. (Again, I think I was not clear.)

>I don't consider that a "failure" any more than I consider flying into the
>side of a mountain a structural failure. Particulates dense enough to shut
>down an engine are dense enough that the pilot had no business flying into
>them in the first place (or was unfortunate enough to be overtaken by a
>cloud).

Make sure I have this straight...

If an engine stops (against the pilot's wishes) in flight becuase it
can no longer get fuel, that's "engine failure". If it stops because
it can no longer get air, that's just "pilot error"?

--kyler

Peter Duniho

November 28th 03, 06:46 PM

"Kyler Laird" > wrote in message
...
> If an engine stops (against the pilot's wishes) in flight becuase it
> can no longer get fuel, that's "engine failure". If it stops because
> it can no longer get air, that's just "pilot error"?

Yes and no. It depends on why the engine can no longer get fuel. The most
common reason for an engine to be starved of fuel is that the pilot didn't
bring enough fuel along for the trip. This is pilot error. I already made
it clear that I realize this is one of the most common reasons for an engine
failure and that my comments regarding the statistics of engine failures
exclude engine failures due to fuel exhaustion.

Likewise, my comments regarding the statistics of engine failures exclude
engine failures due to a pilot flying into something that causes the air
intake to become clogged.

My comments are specifically targeted at genuine *failures*. That is,
something broke. There are plenty of reasons an engine might stop running,
but not all of them are pertinent to a reliability analysis discussing
failure rates and statistical chances of failure. You seem to keep trying
to introduce irrelevent types of engine failures, while I try to make clear
what it is I'm talking about.

Maybe I haven't been clear enough, but hopefully you're starting to get the
idea of what I'm actually talking about.

Pete

Kyler Laird

November 29th 03, 02:09 AM

"Peter Duniho" > writes:

>My comments are specifically targeted at genuine *failures*. That is,
>something broke.

Ah...o.k. That *is* different and I can appreciate the distinction.

>There are plenty of reasons an engine might stop running,
>but not all of them are pertinent to a reliability analysis discussing
>failure rates and statistical chances of failure. You seem to keep trying
>to introduce irrelevent types of engine failures, while I try to make clear
>what it is I'm talking about.

No, I was coming at it more from the pilot's (rather than the
mechanic's) perspective. It's not "irrelevent" to a pilot when the
engine makes an uncommanded stop in flight. I think it's common for
pilots to call such stoppages "engine failures." I can see that
there might be a better term for it.

O.k., fuel exhaustion, air starvation, misfueling, ... are no longer
causes of "engine failures". Now to come up with a name for what
people mean when they talk about undesired engine stoppage...

Thanks for sticking with me through this.

--kyler

Peter Duniho

November 29th 03, 02:18 AM

"Kyler Laird" > wrote in message
...
> O.k., fuel exhaustion, air starvation, misfueling, ... are no longer
> causes of "engine failures". Now to come up with a name for what
> people mean when they talk about undesired engine stoppage...

How about "undesired engine stoppage"? :) "Engine interruptus"? I dunno.

> Thanks for sticking with me through this.

No problem...glad I could finally represent my thoughts in a way that was
understandable.

Pete

Big John

November 29th 03, 03:47 AM

Kyler

How about "Pilot induced engine failures" and "Mechanical engine
failures" or "Non Pilot induced engine failures"?

There are probably some more sharp ones out there who can parse your
query and add to a proposed list<G>

Big John

On Sat, 29 Nov 2003 02:09:19 GMT, Kyler Laird >
wrote:

>"Peter Duniho" > writes:
>
>>My comments are specifically targeted at genuine *failures*. That is,
>>something broke.
>
>Ah...o.k. That *is* different and I can appreciate the distinction.
>
>>There are plenty of reasons an engine might stop running,
>>but not all of them are pertinent to a reliability analysis discussing
>>failure rates and statistical chances of failure. You seem to keep trying
>>to introduce irrelevent types of engine failures, while I try to make clear
>>what it is I'm talking about.
>
>No, I was coming at it more from the pilot's (rather than the
>mechanic's) perspective. It's not "irrelevent" to a pilot when the
>engine makes an uncommanded stop in flight. I think it's common for
>pilots to call such stoppages "engine failures." I can see that
>there might be a better term for it.
>
>O.k., fuel exhaustion, air starvation, misfueling, ... are no longer
>causes of "engine failures". Now to come up with a name for what
>people mean when they talk about undesired engine stoppage...
>
>Thanks for sticking with me through this.
>
>--kyler

Kyler Laird

November 29th 03, 02:09 PM

Big John > writes:

>>O.k., fuel exhaustion, air starvation, misfueling, ... are no longer
>>causes of "engine failures". Now to come up with a name for what
>>people mean when they talk about undesired engine stoppage...

>How about "Pilot induced engine failures" and "Mechanical engine
>failures" or "Non Pilot induced engine failures"?

Nope. Those would still be "... engine failures." As Peter has
argued (I think) successfully, they're not failures of the engine.
The difference between such stoppages and the ones we experience
upon shutdown is the intention of the pilot.

I should have consulted the NTSB earlier. Here's a report of a
plane that went down around here recently.
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20020426X00574&key=1
I'm referring to that because I recall (perhaps incorrectly) people
calling it a forced landing due to "engine failure."

Hmmm...how about "engine mismanagement"? (I'm willing to be liberal
with the use of "manage" to include "So...you managed to fly into
quite a bit of ice there...")

I think I'll at least start saying "engine mechanical failure" in an
attempt to be more a bit more clear.

--kyler

Mike Rapoport

November 30th 03, 01:17 AM

Well there is no maitenance on connecting rods and crankshafts.

Mike
MU-2

"Tom S." > wrote in message
...
>
> "Mike Rapoport" > wrote in message
> link.net...
> > I don't have any personally but I have a friend that has had three in
> > 3500hrs. One connecting rod failure in a 210. A crankshaft failure in
an
> > Azetec and I forget the details of the third failure. It has been
> estimated
> > that 10% of Malibus have had inflight engine failures of some kind.
> >
>
> It'd be interesting to know the maintenance history of those birds that
did
> have failures (skimped maintenance, etc).
>
> It's also be interesting to know the total operating hours of the Malibu
> fleet, Lycoming vs. Continental...
>
>

Tom S.

November 30th 03, 01:30 AM

"Mike Rapoport" > wrote in message
hlink.net...
> Well there is no maitenance on connecting rods and crankshafts.
>

....other than preventive.

>
> "Tom S." > wrote in message
> ...
> >
> > "Mike Rapoport" > wrote in message
> > link.net...
> > > I don't have any personally but I have a friend that has had three in
> > > 3500hrs. One connecting rod failure in a 210. A crankshaft failure
in
> an
> > > Azetec and I forget the details of the third failure. It has been
> > estimated
> > > that 10% of Malibus have had inflight engine failures of some kind.
> > >
> >
> > It'd be interesting to know the maintenance history of those birds that
> did
> > have failures (skimped maintenance, etc).
> >
> > It's also be interesting to know the total operating hours of the Malibu
> > fleet, Lycoming vs. Continental...
> >
> >
>
>

Snowbird

November 30th 03, 02:49 PM

(Michael) wrote in message >...
> (Snowbird) wrote
> > In a SE airplane w/ an engine powered vacuum pump and w/out a backup
> > electric pump or backup electric gyros, engine failure will become
> > gyro failure in a minute or so.

> Not true unless the engine seizes. If it keeps windmilling, the gyros
> will keep spinning.

I could be mistaken, but I don't believe windmilling will
produce sufficient vacuum to keep the gyros spinning reliably.

Cheers,
Sydney

G.R. Patterson III

November 30th 03, 03:16 PM

Snowbird wrote:
>
> I could be mistaken, but I don't believe windmilling will
> produce sufficient vacuum to keep the gyros spinning reliably.

FWIW, my engine at idle won't keep the vacuum gauge in the green, but the AI
and DG appear to work properly. Would a windmilling prop produce as much as
1,000 rpm?

George Patterson
Some people think they hear a call to the priesthood when what they really
hear is a tiny voice whispering "It's indoor work with no heavy lifting".

Mike Rapoport

December 1st 03, 12:17 AM

What preventive maitenance is done on either crankshafts of connecting rods?

Mike
MU-2

"Tom S." > wrote in message
...
>
> "Mike Rapoport" > wrote in message
> hlink.net...
> > Well there is no maitenance on connecting rods and crankshafts.
> >
>
> ...other than .preventive
>
> >
> > "Tom S." > wrote in message
> > ...
> > >
> > > "Mike Rapoport" > wrote in message
> > > link.net...
> > > > I don't have any personally but I have a friend that has had three
in
> > > > 3500hrs. One connecting rod failure in a 210. A crankshaft failure
> in
> > an
> > > > Azetec and I forget the details of the third failure. It has been
> > > estimated
> > > > that 10% of Malibus have had inflight engine failures of some kind.
> > > >
> > >
> > > It'd be interesting to know the maintenance history of those birds
that
> > did
> > > have failures (skimped maintenance, etc).
> > >
> > > It's also be interesting to know the total operating hours of the
Malibu
> > > fleet, Lycoming vs. Continental...
> > >
> > >
> >
> >
>
>

Snowbird

December 1st 03, 12:45 AM

(Michael) wrote in message >...
> (Snowbird) wrote
> > One observation from the recent ASF/FAA vacuum failure study
> > was that pilots who lost only their AI (electric HSI did not
> > fail) did not lose control of the airplane, while a significant
> > number of pilots (same aircraft) lost control when they lost
> > both. There was no correlation to time in type or total time.

> > This result suggests to me that it might be a mistake to
> > extrapolate from "lose AI no problem" to "lose gyros no
> > problem".

> That's somewhat valid. I don't worry about this situation for two
> reasons: First, I have dual vacuum pumps, so loss of both gyros
> simultaneously is very, very unlikely.

I wasn't so much concerned about your personal setup but about
your posting history, which is to pipe up whenever the subject
of gyro failure (and bad outcomes thereof) are discussed and
say something to the effect of well, I've had a gyro failure in
actual and it was no big deal so contrary to popular opinion I
don't think it's something a proficient pilot needs to sweat
about. (I paraphrase here, and perhaps that wasn't the message
you intended to convey, but it's the message I and, I think,
others, have garnered from your posts)

That's why I think the distinction between a single instrument
failure, and vacuum failure (loss of two instruments) may be
relevant to point out.

> I've already made my feelings about flying IMC with a single
> dry pump and no backups well known, but in case anyone missed it -
> it's stooopid.

Actually, I'm glad to hear you say this. The impression that
I've received from your previous posts is that you believed a
vacuum failure should be no big deal at all to a proficient pilot.
Not a reason to abort the flight, declare an emergency, and
request no-gyro vectors to the nearest ILS, for example (which
is my notion).

If that's not the case, I'm at a bit of a loss as to how to
interpret some of what you've previously posted.

If that is the case, I'm at a bit of a loss as to why you
feel lack of backup is so stupid -- if it's no big deal and any
proficient pilot should be able to cope without breaking a
sweat, why is backup important? If the cause of accidents
following vacuum or gyro failure is lack of proper, recurrant
training, why not just invest in training instead of redundant
instrumentation or vacuum sources--isn't that what you've
suggested in the past when the point has been raised?

> The reason I say it's somewhat valid is this - my (admittedly somewhat
> limited) experience as an instrument instructor is that most people
> miss having the DG a lot more than they miss having the AI.

That's certainly true for me.

[nb this originally referred to "ugly outcomes" to gyro failures
in IMC]
> > There are currently no "real stats" which prove or disprove
> > the contention that this ugliness is entirely due to improper
> > training.

> No, but that's the way to bet. It's certainly how my insurance
> company is betting - I'm now required to take a full IPC with engine
> cuts every year in make and model, regardless of recency of
> experience, if I want to keep my relatively low rates.

Apples and oranges to the topic under discussion here, which was
whether the "ugly outcomes" of vacuum failure are entirely due
to improper training.

Unless I'm missing something, there is no requirement that an
IPC necessarily include partial panel work, so it's not clear
to me how your insurance company votes on this topic. The
principle cause of accidents in light twins is not related to
vacuum failure due to redundant systems.

Cheers,
Sydney

Tom S.

December 1st 03, 01:04 AM

"Mike Rapoport" > wrote in message
hlink.net...
> What preventive maitenance is done on either crankshafts of connecting
rods?
>

Oil changes for one.

> Mike
> MU-2
>
>
> "Tom S." > wrote in message
> ...
> >
> > "Mike Rapoport" > wrote in message
> > hlink.net...
> > > Well there is no maitenance on connecting rods and crankshafts.
> > >
> >
> > ...other than .preventive
> >
> > >
> > > "Tom S." > wrote in message
> > > ...
> > > >
> > > > "Mike Rapoport" > wrote in message
> > > > link.net...
> > > > > I don't have any personally but I have a friend that has had three
> in
> > > > > 3500hrs. One connecting rod failure in a 210. A crankshaft
failure
> > in
> > > an
> > > > > Azetec and I forget the details of the third failure. It has been
> > > > estimated
> > > > > that 10% of Malibus have had inflight engine failures of some
kind.
> > > > >
> > > >
> > > > It'd be interesting to know the maintenance history of those birds
> that
> > > did
> > > > have failures (skimped maintenance, etc).
> > > >
> > > > It's also be interesting to know the total operating hours of the
> Malibu
> > > > fleet, Lycoming vs. Continental...
> > > >
> > > >
> > >
> > >
> >
> >
>
>

Mike Rapoport

December 1st 03, 02:33 AM

Oil changes do not affect the probability of crankshaft or connecting rod
failure..

Mike
MU-2

"Tom S." > wrote in message
...
>
> "Mike Rapoport" > wrote in message
> hlink.net...
> > What preventive maitenance is done on either crankshafts of connecting
> rods?
> >
>
> Oil changes for one.
>
> > Mike
> > MU-2
> >
> >
> > "Tom S." > wrote in message
> > ...
> > >
> > > "Mike Rapoport" > wrote in message
> > > hlink.net...
> > > > Well there is no maitenance on connecting rods and crankshafts.
> > > >
> > >
> > > ...other than .preventive
> > >
> > > >
> > > > "Tom S." > wrote in message
> > > > ...
> > > > >
> > > > > "Mike Rapoport" > wrote in message
> > > > > link.net...
> > > > > > I don't have any personally but I have a friend that has had
three
> > in
> > > > > > 3500hrs. One connecting rod failure in a 210. A crankshaft
> failure
> > > in
> > > > an
> > > > > > Azetec and I forget the details of the third failure. It has
been
> > > > > estimated
> > > > > > that 10% of Malibus have had inflight engine failures of some
> kind.
> > > > > >
> > > > >
> > > > > It'd be interesting to know the maintenance history of those birds
> > that
> > > > did
> > > > > have failures (skimped maintenance, etc).
> > > > >
> > > > > It's also be interesting to know the total operating hours of the
> > Malibu
> > > > > fleet, Lycoming vs. Continental...
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>

Tom S.

December 1st 03, 03:21 AM

"Mike Rapoport" > wrote in message
link.net...
> Oil changes do not affect the probability of crankshaft or connecting rod
> failure..
>
So having bad or inadequate oil to lubricate the crankshaft and connecting
rods don't make much difference? I must be working with different engines.

Mike Rapoport

December 1st 03, 03:39 AM

Presumably you have never worked on an engine at all.. Please describe how
changing engine oil keeps a connecting rod from breaking in half.

Mike
MU-2

"Tom S." > wrote in message
...
>
> "Mike Rapoport" > wrote in message
> link.net...
> > Oil changes do not affect the probability of crankshaft or connecting
rod
> > failure..
> >
> So having bad or inadequate oil to lubricate the crankshaft and connecting
> rods don't make much difference? I must be working with different engines.
>
>
>
>
>

Kyler Laird

December 1st 03, 02:09 PM

"Mike Rapoport" > writes:

>Well there is no maitenance on connecting rods and crankshafts.

But do you agree that components that require maintenance (propeller,
cylinders, engine mounts, ...) can cause/accelerate crankshaft
failures?

--kyler

Tom S.

December 1st 03, 02:55 PM

"Mike Rapoport" > wrote in message
link.net...
> Presumably you have never worked on an engine at all.. Please describe
how
> changing engine oil keeps a connecting rod from breaking in half.
>

Please lose the patronizing tone that you came into this discussion with,
then I'll continue with my QUESTION. (No wonder that one guy said he came
into the group, then left after seeing the abuse some dole out.)

Tom S.

December 1st 03, 02:56 PM

"Kyler Laird" > wrote in message
...
> "Mike Rapoport" > writes:
>
> >Well there is no maitenance on connecting rods and crankshafts.
>
> But do you agree that components that require maintenance (propeller,
> cylinders, engine mounts, ...) can cause/accelerate crankshaft
> failures?
>
Nah...Mike says you can completely neglect them.

Snowbird

December 1st 03, 02:56 PM

(Captain Wubba) wrote in message >...
> (Snowbird) wrote in message >...

> > (Captain Wubba) wrote in message >...
> > > Because I can control these problems. If I do a proper preflight, the
> > > probability of fuel contamination is very, very low. If I do the
> > > proper fuel calculations and check the fuel levels and carry proper
> > > reserves, I'm not going to run out of gas.

> > When you fill the tanks after each cross country flight, do you
> > calculate the fuel you actually had remaining, and compare it
> > to your calculated fuel reserve?

> Not after every one. But after some percentage...probably around 1/4
> of the time. I've caught one FBO that didn't give me all the fuel I
> asked for this way. They were not trying to cheat me, but it was a
> miscomminication with their lineboy. Wasn't a serious problem...I
> always carry at least a 2 hour reserve (60 gallon tanks on a Beech
> Musketeer that drinks 9 GPH), so I got in with one and a half hour
> reserve instead of 2.5. Hard to notice how 10 gallons looks in a tank.

Well, but I hope you can see here's the accident chain unfolding.
Now consider that you shot an instrument approach, went missed,
and flew to your alternate 1/2 hr away (you planned to land w/
your 2 hr reserve). Then you're asked to hold -- no problem,
you've got 2 hrs of fuel. Except more than an hour of it is actually
missing. Something similar was the big "white hair" moment
for me, except that we landed safely.

A practical suggestion though: buy a fuel stick, or simply tie a
lanyard to a paint stirrer. Start calibrating. You can do it as
a single step -- fly a tank dry, then fill it in 5 gallon increments
and measure. Or you can do it by sticking the tank, filling it, and
noting the stick reading and gallons. When you get enough data,
fit it (obviously care must be taken not to extrapolate outside the
data).

I can notice 10 missing gallons in my tank because we have a
calibrated fuel stick and unless the tanks are full to the brim,
it tells me what's in there to w/in a gallon or so.

> Indeed. But I keep two hour reserves on cross country flights in my
> Musketeer. No reason not to...it's almost always just me and my wife
> (and soon our little one:)

Heh. Heh.

As the veteran of many XC trips with two adults and a little one,
let me predict you may shortly be asked to fit more stuff in the
plane than you've ever dreamed. You might even find it necessary
to leave some fuel behind -- unless your wife is a dedicated
Baby Minimalist who heads off for the weekend with a sling, a
diaperbag, and a bed rail. How is your W&B envelope? Might
want to start planning how much luggage you can take with your wife
and baby in the back seat....

> > I just feel that it's a mistake to conclude that no pilot
> > who runs out of fuel in flight did so, or that no pilot
> > who does so will ever run out of fuel in flight.

> I didn't mean to imply that.

Good. I misunderstood you then. I thought you were singing another
refrain of the song "only stupid pilots run out of fuel, I'm a smart
pilot who always carries extra fuel so it'll never happen to me."

> eat lunch at the airport almost every day, sitting in the GA lot
> watching the planes. And you would be stunned by the number of pilots
> I see who don't do *any* preflight.

I might well be. OTOH, is it also possible that the preflight took
place out-of-sight? For example, we preflight in the hangar..pull
over to the pumps and fuel up...park on the ramp. Now our pax arrive
and we go out on the ramp, help them in, and fly off. I suppose
it looks like we don't do *any* preflight.

> From reviewing the NTSB database, it appears the majority of
> fuel-exhaustion accidents are not the result of a simple
> miscalculation. They tend to be a chain of bad decisions

I agree with the "chain of bad decisions" but I don't think
that excludes pilots who felt they were exercising due care
(and who maybe looked like they were, to a reasonable guy,
at the time -- the accident chain is always clearer w/
hindsight)

I know of two fuel exhaustion accidents personally. One
was eerily similar to the C152 accident you mention (pilot
flew 3 hrs in one direction with a tailwind and figured he
didn't need a fuel stop...overflew 3 airports selling fuel
at about 4 hrs flight time and ran out of gas 5 minutes
later. No accident...he did a perfect landing in a parking
lot).

The other involved a long chain, including an intermittant
problem with engine run-on, an oil change which masked signs
of a fuel leak, a high-wing plane with no convenient strut
or ladder, lack of a calibrated fuel stick, and a decision to
rely upon nearly 500 hrs of carefully documented past fuel
usage and buy partial fuel rather than fill the tanks at a
pricy fuel stop. The NTSB report places much more blame on
the pilot than I personally feel was merited, having been
there. The root cause of the accident was a trashy carburettor
overhaul.

I haven't personally reviewed the NTSB database on this topic,
so I have to defer to you there.

My only point is I think it's a lot easier to mismanage GA fuel
than some people appreciate, especially if you start needing
to make tradeoffs between fuel and load and/or you fly in IMC (I'll
leave the stupidity of flying IMC in a GA single for someone
else in another thread, *heh* *heh*)

Best,
Sydney

Michael

December 1st 03, 05:35 PM

(Snowbird) wrote
> say something to the effect of well, I've had a gyro failure in
> actual and it was no big deal so contrary to popular opinion I
> don't think it's something a proficient pilot needs to sweat
> about. (I paraphrase here, and perhaps that wasn't the message
> you intended to convey, but it's the message I and, I think,
> others, have garnered from your posts)

No, that's basically the message. I don't think it's something a
proficient pilot needs to really sweat. Sure, it could get you - but
it probably won't. I consider it comparable to an engine failure in a
twin after reaching blue line and gear up - it's something you train
for, and if you've trained for it it's not going to be a big deal when
it happens. BTW, I've had that as well, and it wasn't a big deal
either.

> That's why I think the distinction between a single instrument
> failure, and vacuum failure (loss of two instruments) may be
> relevant to point out.

Yes, I think it's VERY important. An analogous situation might be a
stuck valve vs. a total engine failure. In your average light single,
a stuck valve means you're not going to make enough power to climb -
but you will have enough to flatten your glideslope and increase the
options. Therefore, the situation is easier than a total failure. By
the same token, a vacuum failure when established in level cruise is
going to be easier to handle than one on climbout while getting an
amended clearance. No two situations are ever the same - we normally
practice for the worst case.

What makes vacuum failure (as opposed to single gyro failure) ugly is
that two out of three gyros fail (in a typical setup). Of course
that's going to make the situation more difficult. Essentially you're
set up so that a single point failure takes out two important
instruments. I used to fly a TriPacer where it was worse - all three
gyros were vacuum powered. Believe it or not, this is legal - but I
doubt too many pilots could survive a vacuum failure in IMC in that
airplane. Of course it was a wet pump, which is, if my experience and
the experience of the people I know is any guide, more reliable than
the engine that drives it. That airplane, early in its history, was
IFR equipped (to 1950's standards) and was used as a cargo hauler. I
wonder if the pilot knew all his gyros were on one pump.

Anyway, my point is that dual simultaneous failures are more difficult
to handle than individual failures and a proper design won't allow
them to occur with any regularity. Two gyros driven by a single dry
pump does not constitute proper design. That doesn't make it
unflyable, even in IMC, but given the ready availability of wet pumps
for all the popular engines in use on light singles, it's pretty
stupid. Kind of like flying IFR without a handheld GPS - it's doable,
and it was done for years, but given how useful they are and how
little they cost, it's pretty dumb not to have one.

My gyro failure situation included only the AI, but on the other hand
it happened during the highest workload phase of flight. Would it
have been more difficult had I lost the DG as well? Certainly.
Dangerous? I doubt it. Handling the AI loss was just too easy, and
doing night hood work with both out isn't all that difficult either.

> > I've already made my feelings about flying IMC with a single
> > dry pump and no backups well known, but in case anyone missed it -
> > it's stooopid.
>
> Actually, I'm glad to hear you say this. The impression that
> I've received from your previous posts is that you believed a
> vacuum failure should be no big deal at all to a proficient pilot.

An engine failure over an airport should also be no big deal at all to
a proficient pilot. That doesn't mean I'm willing to take off when
the oil pressure at idle is well above top redline - even if I'm never
going to be out of glide range of the field (and yes, this was a real
situation).

> If the cause of accidents
> following vacuum or gyro failure is lack of proper, recurrant
> training, why not just invest in training instead of redundant
> instrumentation or vacuum sources--isn't that what you've
> suggested in the past when the point has been raised?

Well, in my opinion the sensible thing to do is to replace the dry
pump with a wet one - given that it's probably more reliable than the
engine that drives it, that's certainly the reasonable and
cost-effective solution in a single engine airplane. But over and
above that - yes, I think recurrent training is preferable to
redundant instrumentation for this.

> > The reason I say it's somewhat valid is this - my (admittedly somewhat
> > limited) experience as an instrument instructor is that most people
> > miss having the DG a lot more than they miss having the AI.
>
> That's certainly true for me.

And that has a lot to do with the kind of airplanes you've flown and
the way they were equipped. In my airplane, I miss the AI more than I
miss the DG. My understanding is that in a jet, loss of all attitude
indicators in IMC is certain death.

> > No, but that's the way to bet. It's certainly how my insurance
> > company is betting - I'm now required to take a full IPC with engine
> > cuts every year in make and model, regardless of recency of
> > experience, if I want to keep my relatively low rates.
>
> Apples and oranges to the topic under discussion here, which was
> whether the "ugly outcomes" of vacuum failure are entirely due
> to improper training.
>
> Unless I'm missing something, there is no requirement that an
> IPC necessarily include partial panel work,

You're missing something. What you say used to be true, but no longer
is. These days, an ICC must consist of "a representative number of
tasks required by the instrument rating practical test" and when you
look at the instrument rating PTS, those tasks are spelled out.
Partial panel approaches (and single engine approaches for twins) are
required.

Michael

Mike Rapoport

December 1st 03, 06:12 PM

I suppose that I agree to a limited extent, but virtually all
crankshaft/connecting rod failures are caused by a flaw/fault in
design/manufacture or installation. Once the crank or connecting rod is
installed, nothing is done to it and it is unseen until overhaul time. A
failure of either of these components is not going to put much, if any,
metal into the oil until the bitter end either..

Mike
MU-2

"Kyler Laird" > wrote in message
...
> "Mike Rapoport" > writes:
>
> >Well there is no maitenance on connecting rods and crankshafts.
>
> But do you agree that components that require maintenance (propeller,
> cylinders, engine mounts, ...) can cause/accelerate crankshaft
> failures?
>
> --kyler

Mike Rapoport

December 1st 03, 06:17 PM

Sorry for the tone but it is incredible to me that anyone thinks that
changing oil protects against structural failure of a crankshaft or
connecting rod. Yes changing the oil makes the bearings, gears, cam/lifters
and all other rubbing/sliding parts last longer but it does not affect
cracking one bit.

Mike
MU-2

"Tom S." > wrote in message
...
>
> "Mike Rapoport" > wrote in message
> link.net...
> > Presumably you have never worked on an engine at all.. Please describe
> how
> > changing engine oil keeps a connecting rod from breaking in half.
> >
>
> Please lose the patronizing tone that you came into this discussion with,
> then I'll continue with my QUESTION. (No wonder that one guy said he came
> into the group, then left after seeing the abuse some dole out.)
>
>

Kyler Laird

December 1st 03, 08:09 PM

"Mike Rapoport" > writes:

>> But do you agree that components that require maintenance (propeller,
>> cylinders, engine mounts, ...) can cause/accelerate crankshaft
>> failures?

>I suppose that I agree to a limited extent, but virtually all
>crankshaft/connecting rod failures are caused by a flaw/fault in
>design/manufacture or installation. Once the crank or connecting rod is
>installed, nothing is done to it and it is unseen until overhaul time. A
>failure of either of these components is not going to put much, if any,
>metal into the oil until the bitter end either..

I was thinking less of metal in the oil than the forces exerted on the
crankshaft. An out-of-balance prop or even a faulty spark plug can
cause out-of-spec. impluses to be exerted on the crankshaft.

I sure don't know how significant that is likely to be though. ('course
you can consider the stories of pilots taking off after prop. strikes as
an extreme.)

--kyler

Michael

December 1st 03, 10:25 PM

(Rich Stowell) wrote
> Geez Michael, settle down! So much stress in the cockpit cannot be
> conducive to learning or safety...

I don't know about you, but I'm not in the cockpit when I post.

> Interesting that I cited a specific source for my statement, which you
> summarily ignore as either irrelevant or incapable of leading to
> numbers that might be relevant to the concerns that started this post.
> Have you read the study I cited?

Yes. It provided no sources on actual engine failure statistics.
Accident statistics are not the same thing at all. Engine failure
statistics from other than GA light piston airplanes also don't cut
it.

> If it "hideously skews the picture" wouldn't that apply to all
> accident numbers from NTSB?

Yes. NTSB numbers are not a valid way of estimating how often any
event occurs, unless that event always results in an accident or
incident. Actually, my experience with NTSB investigations of light
GA crashes leads me to believe that they're not good for anything at
all.

> Each stall/spin accident represent the tip
> of the stall/spin problem. Each engine failure accident represents the
> tip of the engine failure scenario. Accident stats are a poor measure
> of our overall stall/spin awareness, and of our ability to cope with
> engine failures precisely because accident numbers represent the
> relatively few pilots who have had an accident.

Now there's something we can agree on.

BTW, how do you define relatively few?

> But useful information can be gleaned.

Not about the actual rate of incidence of any type of hazard, nor
about relative rates of incidence of various hazards.

> > > Define "rarely." From an industrial accident prevention standpoint,
> > > the theoretical ratio 1:30:300 is often applied wherein for every 331
> > > hazardous encounters of a similar type, only one will progress as far
> > > as an actual accident (significant damage and/or injury). The rest
> > > fall under "incidents" and "hazards."
> >
> > That ratio is nothing more than an expression of ignorance. In
> > reality, depnding on the hazard the numbers can be very different.
>
>
> You neglected to define "rarely."

Consider it equivalent to your definition of "relatively few."

> And which "numbers" can be very
> different -- total numbers, ratios, what?

In this case, I specifically mean the ratios of accidents and
fatalities to total occurrences. The only numbers we REALLY have are
fatalities - a fatality is difficult to cover up, and thus I would
imagine all (or nearly all - say 98% or better) of fatal accidents are
reported and wind up in the NTSB reports. Non-injury accidents are
often not reported - I know of several where the owner did not have
insurance and did not want to bother with reporting anything. Yes, I
know this is a vilation of NTSB 830. BTW, that includes an engine
failure accident where the airplane was almost completely destroyed.

> Granted, total raw numbers
> can be significantly different between different accident types,
> but--as the study of industrial accident prevention postulates--they
> may be linked by comparable ratios or some other normalizing
> parameter.

I think the important word here is 'postulate' which of course means
unproven (and maybe unprovable) assertion. Absent proof of a link,
Occam's Razor calls for the least hypothesis - no link.

> > Industrial safety types love to quote statistics like this to scare
> > people, but in reality there is usually a reason why some hazardous
> > encounters lead to accidents or incidents while most do not. It's not
> > random. These reasons generally have to do with individual skill,
> > knowledge, and experience as well as factors the industrial safety
> > people are never told because they involve routine violations of
> > safety rules. Often the same dynamic plays out in NTSB
> > investigations.
>
>
> The intent was not to scare anyone, but to try to add some perspective
> tying the comparatively rare accident to the unknown (perhaps
> unknowable) number of hazardous situations that are dealt with without
> further incident.

And the perspective is flawed.

> And yes, there are always reasons why aviation
> accidents happen, be it attributable to Software (checklists, SOP's,
> etc.), Hardware (airplane, systems, cockpit layout, etc.), Liveware
> (the pilot, pax, ATC, etc.), Environment, or the interaction of some
> or all of these.

The same is true of industrial accidents. In fact, when you get right
down to it, very few 'accidents' are due to random factors.

> > > In other words, typically 1 out of 331 encounters of a similar type
> > > results in an accident, whether it's precipitated by an engine failure
> > > or an inadvertent stall/spin.
> >
> > No, this is total nonsense because stall-spins and engine failures are
> > not similar. First of all, a mechanical failure generally occurs in a
> > manner that is beyond the pilot's control. When the main seal blows
> > out, or the engine swallows a valve, or a rod goes through a cylinder,
> > or the fuel injectors clog with rust - that's almost always completely
> > independent of pilot skill, knowledge, and judgment. On the other
> > hand, an inadvertent stall-spin is caused by the pilot. Therefore,
> > we're not even looking at the same population.

> The point of the
> pyramidal accident ratio is not to compare engine failures with
> stall/spins. Yes, they are two dissimilar accident types in terms of
> the driving mechanisms -- the engine in one case vs. the pilot in the
> other. But that does not preclude the mix of accidents, hazards, and
> incidents within each population from sharing a common relationship.

Well, no - they might share a common relationship through sheer chance
- but that's not the way to bet.

> From that standpoint, so what if a hole is blown through the crankcase
> and the windscreen gets covered with oil, obscuring the pilot's
> ability to see well enough to land under control. The airplane still
> gets busted and it's still labelled an engine failure accident.
> Likewise, so what if the pilot skids a turn and causes the airplane
> to spin into the ground. It's still a stall/spin accident. But for
> each one of those accidents, there are many more pilots who, with an
> oil-slicked windscreen, were able to land under control; there are
> many more pilots who recognized the developing skid, corrected it, and
> continued under control. The industrial accident maxim only attempts
> to quantify how many within each group were able to avert the
> accident.
>
> You can disagree with the theory or its application (in which case, it
> would be beneficial to put forth an alternative), but can't you do it
> without denigrating?

There's no theory here to disagree with. There is a hypothesis
(advanced without proof) that aviation hazards follow the 1:30:300
distribution, with 331 hazard encounters leading to 30 accidents and 1
fatality (or 30 incidents and 1 accident - depending on how you apply
it). To qualify the hypothesis as a theory, you would need to propose
a logical mechanism for the numerical results. For it to be taken
seriously, you would also need supporting data on the relevant
elements, including some credible data on the rate of hazard
encounters not leading to accidents or incidents. What I am
denigrating here is the attempt to draw conclusions without either.

> This is supposed to be a forum for learning -- is
> this how you treat your students?

This is certainly how a student in the sciences would expect to be
treated if he tried to pass off the 300:30:1 ratio as a theory.

You're attempting to draw some conclusions about the relative
frequency of stall-spin events relative to engine failure events. No
such conclusions are possible if all you have to look at are accident
statistics.

> > Just by virtue of the fact that the pilot allowed the inadvertent
> > stall-spin situation to develop, we can expect that he is less likely
> > to handle it properly. The same is not true of engine failure.
>
> I would disagree thusly: the pilot who does not routinely ("routinely"
> meaning at least 50% of the time) simulate an engine failure followed
> by a glide to landing (even from abeam the numbers would be
> beneficial) is equally as likely not to be able to handle an engine
> failure to a successful landing (i.e.: no accident) as a pilot who
> allows the development of an inadvertent stall/spin.

See, this is another example of a hypothesis (I would not even
consider it a theory) that won't stand the light of day. Where did
you come up with 50%? Are you suggesting that a pilot who only makes
20 landings a year (hardly unusual, given how little most private
pilots fly), of which 10 are simulated engine failures, will do better
with a real engine failure than a pilot who makes 300 landings a year,
of which only 30 are simulated engine failures?

It only makes sense that those who don't practice power-off landings
are less likely to be able to competently perform them when necessary,
but going from that to hard numbers without additional evidence is
simply not reasonable.

> > > In the case of NTSB data, one could
> > > extrapolate to get a feel for the order of magnitude of problems
> > > pilots deal with in a particular category by multiplying the number of
> > > accidents by 331.
> >
> > This is absolutely ridiculous. In addition to the issue of hazard
> > exposure (mechanical engine failures don't discriminate but
> > stall-spins do) there is also the issue of hazard magnitude. Off
> > field landings in gliders, for example, are VERY rarely fatal. The
> > ratio there is 5000:1. On the other hand, I would be amazed if the
> > fatality ratio for midairs was much better than 3:1. 331 may be a
> > good all-around average in aviation (or it may not - data are not
> > available) but to apply it indiscriminately to all types of hazards
> > makes no sense at all.
>
> Be gentle, you're dealing with an idiot after all ;)

I doubt it.

> Please explain
> how an engine failure does not discriminate, yet stall/spin accidents
> do. The typical stall/spin profile involves a typical pilot on a
> typical flight -- sounds pretty indiscriminate to me.

I don't believe a stall-spin involves a typical pilot at all. I
believe a typical pilot will recognize the loss of airspeed long
before a stall, never mind a spin, actually occurs. The pilot who
allows the situation to deteriorate to the point that an inadvertent
stall occurs is way behind the airplane. Letting it spin is worse.

Of course there are exceptions to this. If you fly just a few knots
over stall in turbulent air long enough (and this is a normal flight
mode for gliders) you will eventually stall. I don't know anyone with
more than 100 hours in a glider who has never stalled in a thermal.
If you fail to control yaw at that point, you will spin, and I know a
few people who have. However, because spin training is still the norm
for glider pilots, and because all glider pilots are aware of the
risk, this situation does not seem to be a significant cause of
fatalities. When glider pilots have fatal stall-spins, they have them
the same way power pilots do - when maneuvering to land.

> Please cite your source for the 5000:1 ratio for gliders.

Strictly an estimate based on my experience with the sport. SSA
claims a membership of 14,000. Conservatively speaking, maybe 20% fly
XC, or 2800 people. On average, a XC pilot is going to land out once
a year; more if he's still learning. We have an outlanding-related
fatality once every few years. The last one I recall was Oran Nicks.

> Also, glider
> pilots are always performing engine-out landings, so it would seem to
> make sense that they'd be better at it than those of us who fly
> powered airplanes.

Exactly! Further, it's the more skilled glider pilots who go XC and
thus expose themselves to the risk of outlanding. An outlanding in a
glider is an event that discriminates in favor of the more skilled
pilot, and thus I would expect it to have a very low rate of fatality.
On the other hand, a stall-spin discriminates in favor of the less
skilled pilot, and thus I would expect it to have a higher rate of
fatality. Engine failure (due to mechanical problems) does not
discriminate by skill.

> As for mid-airs, during the period 1977-1986, 40 percent of the
> mid-airs ended without injury.

So my estimate of a minimum 25% fatality rate for midairs (3:1)
doesn't sound too far off. Certainly 1:30:300 is not a good fit.

> As for fatality ratio -- yes, the fatality rates between accident
> types is not at all equal.

Well, I'm glad we can agree on that. Now if we can simply get to the
next obvious step, that being that the accident/incident rates between
different types of hazards are not at all equal, and that therefore no
conclusions about the rate of occurence of various hazards can be
drawn from accident/incident reports, we'll have reached agreement.

Michael

Rich Stowell

December 2nd 03, 06:14 PM

Michael,

Your experience vis-a-vis how NTSB accident numbers (reported) stack
up compared to the actual total number of accidents (reported +
unreported) is not at all unusual. I too know of numerous unreported
accidents. But this isn't peculiar to aviation -- it probably happens
in a lot of different settings and more often than we realize. That's
what makes estimating and/or extrapolating accident information so
difficult. Perhaps if we always stated a number plus-or-minus some
estimate of the error that'd be satisfactory?

Again, my intent was to try to establish some kind of broader context
for the numbers, imprecise as they may be, unknowable as they may be.
Regarding the accident pyramid applied to aviation, see Diehl, Alan E.
"Human Performance and Systems Safety Considerations in Aviation
Mishaps," The International Journal of Aviation Psychology, vol. 1,
no. 2, pp. 97-106; see also Veillette, Patrick R., "Not All Spins Are
Equal," University of Utah, 1986 (notes from a presentation).

"Relatively few" is the 1 accident per 331 (or X) total hazardous
encounters.

(Michael) wrote in message >...

> > I would disagree thusly: the pilot who does not routinely ("routinely"
> > meaning at least 50% of the time) simulate an engine failure followed
> > by a glide to landing (even from abeam the numbers would be
> > beneficial) is equally as likely not to be able to handle an engine
> > failure to a successful landing (i.e.: no accident) as a pilot who
> > allows the development of an inadvertent stall/spin.
>
> See, this is another example of a hypothesis (I would not even
> consider it a theory) that won't stand the light of day. Where did
> you come up with 50%? Are you suggesting that a pilot who only makes
> 20 landings a year (hardly unusual, given how little most private
> pilots fly), of which 10 are simulated engine failures, will do better
> with a real engine failure than a pilot who makes 300 landings a year,
> of which only 30 are simulated engine failures?
>
> It only makes sense that those who don't practice power-off landings
> are less likely to be able to competently perform them when necessary,
> but going from that to hard numbers without additional evidence is
> simply not reasonable.

As a flight instructor charged with the task of educating pilots and
(hopefully) offering them guidance in terms of how often to practice
certain procedures/maneuvers on their own, what frequency do you
recommend in this regard, and on what is that recommendation based? My
suggestion to practice gliding approaches to landing on the order of
50% of the time is based on my anecdotal experience flying with
licensed pilots in the EMT Program, including performing 14,000+
landings, the great majority of which have been gliding approaches in
many types of light airplanes.

I think we'd agree that the number of such practice approaches is
somewhere between 0 percent of the time (airline-type flying) and 100
percent of the time (gliders). Also, and though it hasn't been stated
explicitly, I'm talking in terms of the "average," "typical," "normal"
pilot flying the typical light airplane on a typical flight. That
said, I do believe that an average pilot who performs 10 gliding
approaches out of the 20 approaches annually will be likely to react
appropriately to an engine failure. Now, because this pilot may lack
the breadth of experience of your atypical 300-landings-per-year pilot
who practices gliding 10 percent of the time, the less-experienced
pilot (but who is more representative of the norm) may not be as
precise overall, yet the fundamental skill set needed to cope should
be there nonetheless.

In fact, typical pilots under duress will invariably only be able to
perform as well as their most basic skill set allows. And those skills
that are the most practiced, the most familiar, the most "natural" to
the pilot are the ones that will largely determine the outcome. Again,
this is based on my anecdotal experience instructing 1,000's of pilots
while they are placed under duress during emergency maneuver training
-- typical pilots from across the country who are representative
"products" of our national flight training system.

Also based on my experience, the dominant experience and instincts of
the 300-landings-per-year pilot who practices glides 10 percent of the
time are not those consistent with gliding, but are those consistent
with powered approaches. Such a pilot may actually have to fight
harder against the natural urges/tendencies developed and reinforced
during all those powered approaches.

> I don't believe a stall-spin involves a typical pilot at all.

The numbers and the anecdotal experience of professional
spin/aerobatic flight instructors are totally at odds with your
belief. The typical pilot is trained by the typical flight instructor,
who himself/herself has a marginal understanding of, and marginal
practical experience with, anything related to stalls and spins and
therefore, is incapable of adequately providing stall/spin awareness
training to their students. See "Re-Examination of Stall/Spin
Prevention Training," Transportation Research Record, No. 1379,
National Research Council, Transportation Research Board, 1993, by
Patrick Veillette.

Anecdotally, I see it firsthand every day either flying with, or
providing stall/spin seminars to, typical pilots from all around the
country -- again, they are representative products of our national
flight training system. Moreover, the statistics in every way point to
typically-trained pilots on typical flights: NTSB's special study
covering the years 1967-69 showed that 1/3 of stall/spin accidents
involved pilots with more than 1,000 hours of flight time. The median
pilot experience of those involved in stall/spins was 400 hours.
Though even higher time pilots succumb to stall/spin accidents, we can
profile who is most at risk of an accidental stall/spin as follows:
it's the pilot who has logged fewer than 1,000 hours; who is on a
daytime pleasure flight in good weather; who is in the traffic
pattern; and who is either turning or climbing. Leading up to the
inadvertent stall/spin, the pilot will be distracted into making a
critical error in judgment. Fixation on the unfolding accident will
effectively render 1 in 3 pilots deaf to the blaring stall warning
horn. And pilots with fewer than either 500 hours total time, or 100
hours in type, are more likely to encounter an inadvertent stall/spin
than to have a genuine engine failure.

Consider the following 1987 stats as well: the U.S. boasted 699,653
active pilots who collectively logged an estimated 47.9 million flight
hours. Amortized, pilots averaged 68 hours each that year
(unfortunately, this average had decreased to less than 50 hours per
pilot per year during the 1990's). Consider, too, that the average
active flying career of a general aviation pilot is estimated to be 17
years. Hence, the typical pilot will accumulate close to 1,200 hours
total time. The majority of pilots--students, private pilots,
CFIs--remain squarely in the bull's-eye of the stall/spin accident
zone throughout their aviation careers. They are the ones encountering
accidental stalls and spins, most of which are just hazardous
encounters, some of which result in accidents.

>> As for mid-airs, during the period 1977-1986, 40 percent of the
>> mid-airs ended without injury.
>So my estimate of a minimum 25% fatality rate for midairs (3:1)
>doesn't sound too far off. Certainly 1:30:300 is not a good fit.

Somewhere, somehow the discussion shifted from "total accidents" to
"fatal accidents only." The 1:30:300 is all hazardous encounters
leading to all accidents, not total accidents vs. fatal accidents vs.
some-injury accidents vs. non-injury accidents. Regarding mid-airs,
the question would be, "for each mid-air, how many times are airplanes
coming close enough to each other to be considered a hazardous
encounter (especially when pilots in both airplanes have their heads
buried in the cockpit on a clear VFR day)?" Maybe 331 times as many as
the total number of mid-airs that resulted in accidents (whether those
on board were injured, killed, or not)???

Rich
http://www.richstowell.com

Big John

December 3rd 03, 02:42 PM

Kyler

Another true (War) story.

T-28A

7 cyl 900 HP engine. (128+ HP per cyl)
2 blade Aero-Products prop (big wide paddle blades to absorb HP)
Prop shaft cut with a square corner where it transitioned to throw.
At original cruise rpm viborations/stresses caused prop shaft to break
off and prop depart plane.
Result - dead stick with prop missing.

Fixes tried.

1. Tried 3 blade prop which reduced stress on crank - worked but cost
too much to throw away the relatively new 2 blade props and get
new 3 blade props.

2. Dissambled engine and under cut (rounded) square corner betweem
shaft and throw. More failures.

3. Set up a restricted rpm range that could be transitioned but not
fly steady state in.

4. Raised cruise rpm 150 rpm changing stress on crank. These two
worked but reduced range and duraation a lot. Had to refuel after
every training mission vs flying two missions on one load of fuel.

Looks like this true life story supports both sides of the argument?

Big John

On Mon, 01 Dec 2003 20:09:35 GMT, Kyler Laird >
wrote:

>"Mike Rapoport" > writes:
>
>>> But do you agree that components that require maintenance (propeller,
>>> cylinders, engine mounts, ...) can cause/accelerate crankshaft
>>> failures?
>
>>I suppose that I agree to a limited extent, but virtually all
>>crankshaft/connecting rod failures are caused by a flaw/fault in
>>design/manufacture or installation. Once the crank or connecting rod is
>>installed, nothing is done to it and it is unseen until overhaul time. A
>>failure of either of these components is not going to put much, if any,
>>metal into the oil until the bitter end either..
>
>I was thinking less of metal in the oil than the forces exerted on the
>crankshaft. An out-of-balance prop or even a faulty spark plug can
>cause out-of-spec. impluses to be exerted on the crankshaft.
>
>I sure don't know how significant that is likely to be though. ('course
>you can consider the stories of pilots taking off after prop. strikes as
>an extreme.)
>
>--kyler

Michael

December 4th 03, 05:21 PM

(Rich Stowell) wrote
> Your experience vis-a-vis how NTSB accident numbers (reported) stack
> up compared to the actual total number of accidents (reported +
> unreported) is not at all unusual. I too know of numerous unreported
> accidents. But this isn't peculiar to aviation -- it probably happens
> in a lot of different settings and more often than we realize. That's
> what makes estimating and/or extrapolating accident information so
> difficult. Perhaps if we always stated a number plus-or-minus some
> estimate of the error that'd be satisfactory?

Well, it would be satisfactory if you had a valid way of estimating
the error. However, this still requires data. It's really very
unfortunate that data collection in GA is a bad joke. It's a lot
better at the Part 135/121 levels. For example, in those operations
every engine failure is reported (at least for turbine engines). A
skydiver friend of mine once looked up engine failure rates on the
PT-6 engines that power Twin Otters. The numbers looked artificailly
low to him. He started making phone calls to friends. It's not easy
data to get, but his best estimate is that Twin Otters in Part 91
service have an engine failure rate about 300 times higher than in
Part 91 service. He admits that the real number could be as low as 50
and as high as 1000, because of uncertainties in how operating hours
are estimated as well as uncertainties in which inciddents were
unique.

It's very frustrating as an instructor not to be able to give your
student solid estimates on which risks are truly significant, but the
alternative (reaching firm conclusions from nonexistent numbers) is
far worse.

> "Relatively few" is the 1 accident per 331 (or X) total hazardous
> encounters.

Well, that's great - now define hazardous encounters. With engine
failure, it's easy. The engine stops making power (or stops making
sufficient power to maintain level flight) and you have an encounter.
With off-field landings it's easy - when you commit to an off-field
landing, you have an encounter. Stall-spins are harder. Does the
hazard encounter start when autorotation begins? When the stall
breaks? When the buffet starts? When the stall horn goes off? See
the problem?

> As a flight instructor charged with the task of educating pilots and
> (hopefully) offering them guidance in terms of how often to practice
> certain procedures/maneuvers on their own, what frequency do you
> recommend in this regard, and on what is that recommendation based?

Whatever is required to maintain proficiency. If during your
recurrent training cycle you handle the engine failure competently
(meaning accomplish the task smoothly and with the successful outcome
never seriously in doubt) then you are maintaining proficiency.
Otherwise you are not.

Specific numbers are very much a function of the airplane and pilot
proficiency, and one size does not fit all.

> I think we'd agree that the number of such practice approaches is
> somewhere between 0 percent of the time (airline-type flying) and 100
> percent of the time (gliders). Also, and though it hasn't been stated
> explicitly, I'm talking in terms of the "average," "typical," "normal"
> pilot flying the typical light airplane on a typical flight. That
> said, I do believe that an average pilot who performs 10 gliding
> approaches out of the 20 approaches annually will be likely to react
> appropriately to an engine failure.

I think so too, assuming that what you mean by react appropriately is
point the plane someplace reasonable and maintain proper flying speed
to the flare. I doubt he will select the optimal location or make a
great landing, but those things are probably not crucial to his
survival.

> Now, because this pilot may lack
> the breadth of experience of your atypical 300-landings-per-year pilot
> who practices gliding 10 percent of the time, the less-experienced
> pilot (but who is more representative of the norm) may not be as
> precise overall, yet the fundamental skill set needed to cope should
> be there nonetheless.

No argument.

> In fact, typical pilots under duress will invariably only be able to
> perform as well as their most basic skill set allows.

Define most basic skill set. Keep in mind that for some, this will
include night partial panel flying. For others, it may be
substantially more limited.

> And those skills
> that are the most practiced, the most familiar, the most "natural" to
> the pilot are the ones that will largely determine the outcome. Again,
> this is based on my anecdotal experience instructing 1,000's of pilots
> while they are placed under duress during emergency maneuver training
> -- typical pilots from across the country who are representative
> "products" of our national flight training system.

I'm not convinced that's true. I suspect that the pilots who
voluntarily get emergency maneuvers training are the same pilots who
doubt their ability to handle emergencies. Such doubts are usually
justified.

> > I don't believe a stall-spin involves a typical pilot at all.
>
> The numbers and the anecdotal experience of professional
> spin/aerobatic flight instructors are totally at odds with your
> belief.

So how many inadvertent stall-spins do they get to see under normal
conditions?

> The typical pilot is trained by the typical flight instructor,
> who himself/herself has a marginal understanding of, and marginal
> practical experience with, anything related to stalls and spins and
> therefore, is incapable of adequately providing stall/spin awareness
> training to their students.

That's probably true, but on the other hand most modern airplanes have
to be pretty severely mishandled to cause an inadvertent spin. The
same is not true of gliders and aerobatic airplanes, but the people
flying those tend to be trained by a completely different sort of
instructor.

> And pilots with fewer than either 500 hours total time, or 100
> hours in type, are more likely to encounter an inadvertent stall/spin
> than to have a genuine engine failure.

Why do you keep going back to the patently unprovable? All we know is
that they are more likely to have an accident caused by stall-spin
rather than engine failure. This tells us nothing about the
likelihood of encountering either hazard.

Now let's consider something else. A pilot who flies 200 hours a year
is 10 times more likely to have an engine failure than one who flies
20 hours a year, since engine failure is not under his control. Are
you seriously suggesting that a pilot who flies 200 hours a year is 10
times more likely to inadvertently spin than one who flies 20 hours a
year? I would argue that he is LESS likely to inadvertently spin,
since the higher level of proficiency that is a nearly inevitable
result of flying a lot and often will make him less likely to miss the
rather obvious clues.

> Consider the following 1987 stats as well: the U.S. boasted 699,653
> active pilots who collectively logged an estimated 47.9 million flight
> hours. Amortized, pilots averaged 68 hours each that year
> (unfortunately, this average had decreased to less than 50 hours per
> pilot per year during the 1990's).

However, only half of those are private pilots. Tens of thousands are
professional pilots who fly hundreds of hours a year. Thus the
reality is that a large number (maybe the majority) of these 'active'
private pilots are actually flying less than 20 hours a year. IMO it
is not possible for such a pilot to be proficient at all. In fact,
I'm going to take back what I said - if the average pilot is indeed
flying 20 hours a year, then I will readily admit that inadvertent
stall-spin accidents are going to happen to the average pilot. I
guess my point is that they ought not to happen to the proficient
pilot. Instead of looking at total hours, we should really be looking
at hours flown a year, and even then there are other factors since not
all hours are created equal.

> Somewhere, somehow the discussion shifted from "total accidents" to
> "fatal accidents only." The 1:30:300 is all hazardous encounters
> leading to all accidents, not total accidents vs. fatal accidents vs.
> some-injury accidents vs. non-injury accidents. Regarding mid-airs,
> the question would be, "for each mid-air, how many times are airplanes
> coming close enough to each other to be considered a hazardous
> encounter (especially when pilots in both airplanes have their heads
> buried in the cockpit on a clear VFR day)?" Maybe 331 times as many as
> the total number of mid-airs that resulted in accidents (whether those
> on board were injured, killed, or not)???

Sure. I guarantee you that there is SOME definiton of "close enough
to each other to be considered a hazardous encounter" that will make
the numbers work. By the same token, there is SOME definiton of
"stall-spin hazard" that will make the numbers work. This is
meaningless.

Michael

Rich Stowell

December 5th 03, 07:20 PM

(Michael) wrote in message >...

> It's very frustrating as an instructor not to be able to give your
> student solid estimates on which risks are truly significant, but the
> alternative (reaching firm conclusions from nonexistent numbers) is
> far worse.

I agree about the frustration. I disagree that I was in any way trying
to reach firm conclusions; just trying to offer some sense of the
scope of the potential problem, be it engine failures or stall/spins.

And I do think it is fair in the case of the stall/spin, for example,
to say that the last maneuver performed by nearly one out of four
pilots who's aviation career has ended in death and who also ended up
in the NTSB database was a stall/spin. This does provide some context
about the stall/spin risk, especially in the accident process leading
to generation of an NTSB report.

> > As a flight instructor charged with the task of educating pilots and
> > (hopefully) offering them guidance in terms of how often to practice
> > certain procedures/maneuvers on their own, what frequency do you
> > recommend in this regard, and on what is that recommendation based?
>
> Whatever is required to maintain proficiency. If during your
> recurrent training cycle you handle the engine failure competently
> (meaning accomplish the task smoothly and with the successful outcome
> never seriously in doubt) then you are maintaining proficiency.
> Otherwise you are not.

But what about in between the recurrent training cycle? Do you make
any recommendations to your students at all in this regard? What to
work on, how to work on it, what frequency to practice? And in terms
of "smoothly with the successful outcome never seriously in doubt" --
do you apply Practical Test Standards to the tasks -- which are
minimum acceptable standards, i.e.: training to the lowest common
denominator -- or do you challenge your students to be better than the
average, the minimum standard? And if you challenge them to take their
flying to the next level, I would assume that would be based on your
own experience, both personally and as an instructor dealing with the
problems, errors, and misunderstandings your students commonly have
when they fly with you, no?

And I would bet that sans any hard scientific data to support your
anecdotal experience, you could tell me with reasonable certainty
where the problem areas will be, specifically what the errors will be,
etc. that you will encounter with the majority of your students under
certain tasks.

> Specific numbers are very much a function of the airplane and pilot
> proficiency, and one size does not fit all.

For the majority of GA pilots flying GA airplanes, I have not found
that to be the case at all. The problems I deal with with my students
all fall within a pretty well-defined envelope across the board,
across light, single-engine, GA airplanes. In fact, I would say I've
found it much more difficult for higher time pilots to break their bad
habits simply because the habits have been ingrained for far too long.
The typical profile of the pilot I fly with is a pilot who is active
in general aviation, active in the ratings process, active in the
pursuit of knowledge, experience, safety, and who has 100 to 600 hours
total time. These pilots come from all over the U.S., from all kinds
of flight schools, flying all kinds of light, single-engine airplanes.
And I often fly with them in the equipment they are used to flying.
Anything from the Cirrus SR20/22, to the J-3 Cub, to the C-206 Amphib,
to the Pitts, Pipers, Cessnas, RV's, Zlins, even rarer airplanes like
the Aero Subaru and the FAA Bravo.

In that sense, the pilots I deal with are likely above the average in
terms of their approach to flying and flight safety -- that's why they
are training with me. That and the realization that the primary flight
training process often leaves a lot to be desired in terms of dealing
with many different safety issues, not to mention the pure art of
flying the airplane.

> > In fact, typical pilots under duress will invariably only be able to
> > perform as well as their most basic skill set allows.
>
> Define most basic skill set. Keep in mind that for some, this will
> include night partial panel flying. For others, it may be
> substantially more limited.
>
> > And those skills
> > that are the most practiced, the most familiar, the most "natural" to
> > the pilot are the ones that will largely determine the outcome. Again,
> > this is based on my anecdotal experience instructing 1,000's of pilots
> > while they are placed under duress during emergency maneuver training
> > -- typical pilots from across the country who are representative
> > "products" of our national flight training system.
>
> I'm not convinced that's true. I suspect that the pilots who
> voluntarily get emergency maneuvers training are the same pilots who
> doubt their ability to handle emergencies. Such doubts are usually
> justified.

See above about the typical pilot profile of those I fly with -- they
are likely above average and at least recognize and deal with any
issues they may have. But for each one of the pilots who takes spin,
EMT, or aerobatic training for safety reasons, there may be scores of
others who have no clue, or who have simply given up and left aviation
altogether because of unaddresses issues/fears that could have been
dealt with.

> > > I don't believe a stall-spin involves a typical pilot at all.
> >
> > The numbers and the anecdotal experience of professional
> > spin/aerobatic flight instructors are totally at odds with your
> > belief.
>
> So how many inadvertent stall-spins do they get to see under normal
> conditions?

I'm not sure I understand the question...

> > The typical pilot is trained by the typical flight instructor,
> > who himself/herself has a marginal understanding of, and marginal
> > practical experience with, anything related to stalls and spins and
> > therefore, is incapable of adequately providing stall/spin awareness
> > training to their students.
>
> That's probably true, but on the other hand most modern airplanes have
> to be pretty severely mishandled to cause an inadvertent spin.

Not true -- I routinely demonstrate one variant of the classic skidded
turn base-to-final at altitude with students, and in every single
spins-approved airplane I've ever tried this in, I've been successful
entering a spin from a left turn, with 1200-1800 rpm, without any
aileron, with less than full rudder and elevator inputs, and with the
ball less than 1/2 ball width out of center. This has been true even
in spins-approved airplanes that either would not, or were very
reluctant to, perform a left spin entered normally.

See also "Rudder and Elevator Effects on the Incipient Spin
Characteristics of a Typical General Aviation Training Aircraft." AIAA
Paper 93-0016. Reno, NV: January, 1993, by Patrick Veillette.

> > And pilots with fewer than either 500 hours total time, or 100
> > hours in type, are more likely to encounter an inadvertent stall/spin
> > than to have a genuine engine failure.
>
> Why do you keep going back to the patently unprovable? All we know is
> that they are more likely to have an accident caused by stall-spin
> rather than engine failure. This tells us nothing about the
> likelihood of encountering either hazard.

Thos enumbers are from an NTSB study. I'm notmaking them up. Perhaps
you'd be happier if I prefaced with "Pilots who make it into the NTSB
database share these characteristics..."

> Now let's consider something else. A pilot who flies 200 hours a year
> is 10 times more likely to have an engine failure than one who flies
> 20 hours a year, since engine failure is not under his control. Are
> you seriously suggesting that a pilot who flies 200 hours a year is 10
> times more likely to inadvertently spin than one who flies 20 hours a
> year? I would argue that he is LESS likely to inadvertently spin,
> since the higher level of proficiency that is a nearly inevitable
> result of flying a lot and often will make him less likely to miss the
> rather obvious clues.

You admitted yourself, all flight time is not equal. In that regard, I
would say the pilot who flies 200 hours a year of white-knuckled
X-country, averaging one power-on landing every 2 hours, who is
deathly afraid of stalls to begin with and has never spun, and flies
by the adage "maintain lots of extra flying speed just in case" is far
more likely to encounter an inadvertent stall/spin in a stall/spin
critical situation than a pilot who flies 20 hours a year in his
Pitts, 30 minutes at a shot, performing advanced aerobatic maneuvers
and averaging 4 gliding landings per hour (my former Pitts partner did
just this last year). I'd bet on the survival of this Pitts pilot over
the other one in a similar stall/spin critical scenario.

Perhaps a better gage of a pilot's ability to deal with stall/spin
critical operations is not flight time, but rather the number of
landings per hour. After all, one trip around the pattern exercises
many, many critical piloting skills. It would be interesting perhaps
to do a study with this as the hypothesis -- would this interest
you???

Rich
http://www.richstowell.com

Michael

December 8th 03, 04:09 PM

(Rich Stowell) wrote
> And I do think it is fair in the case of the stall/spin, for example,
> to say that the last maneuver performed by nearly one out of four
> pilots who's aviation career has ended in death and who also ended up
> in the NTSB database was a stall/spin. This does provide some context
> about the stall/spin risk, especially in the accident process leading
> to generation of an NTSB report.

Yes, this provides some context. Where I disagree is that it provides
any information as to the relative occurrences of stall/spins vs.
engine failures.

> But what about in between the recurrent training cycle? Do you make
> any recommendations to your students at all in this regard?

Yes - but they are specific to the individual. It can't be otherwise.
I've done recurrent training for a variety of people ranging from low
time private pilots on end of the scale to an airline captain with 5
digit time on the other.

> What to
> work on, how to work on it, what frequency to practice? And in terms
> of "smoothly with the successful outcome never seriously in doubt" --
> do you apply Practical Test Standards to the tasks -- which are
> minimum acceptable standards, i.e.: training to the lowest common
> denominator -- or do you challenge your students to be better than the
> average, the minimum standard?

I apply the minimum standard to decide if the person gets a signature
in his logbook certifying that he has completed a BFR/ICC. Beyond
that, I tailor the training to the individual. The guy with less than
10 hours IMC time is challenged when I give him the hardest task of
the flight - I fail his vacuum gyros and autopilot and he has to hand
fly the GPS approach. The airline captain gets to do a single engine
hand flown ILS to CAT II minima as a warmup. The idea that one size
fits all is ridiculous.

> > Specific numbers are very much a function of the airplane and pilot
> > proficiency, and one size does not fit all.
>
> For the majority of GA pilots flying GA airplanes, I have not found
> that to be the case at all. The problems I deal with with my students
> all fall within a pretty well-defined envelope across the board,
> across light, single-engine, GA airplanes. In fact, I would say I've
> found it much more difficult for higher time pilots to break their bad
> habits simply because the habits have been ingrained for far too long.
> The typical profile of the pilot I fly with is a pilot who is active
> in general aviation, active in the ratings process, active in the
> pursuit of knowledge, experience, safety, and who has 100 to 600 hours
> total time.

In other words, you're mostly flying with low time pilots. I suppose
the lower the experience level, the more consistent the performance.
After all, at zero hours most people perform about the same :)

Seriously, because of the kind of instruction you do, your clientele
is self-selected. I think that tends to homogenize the sample.

> In that sense, the pilots I deal with are likely above the average in
> terms of their approach to flying and flight safety -- that's why they
> are training with me.

One could just as easily say that they lack confidence and feel the
need for additional training in emergency procedures, and maybe the
lack of confidence is justified.

> > > > I don't believe a stall-spin involves a typical pilot at all.
> > >
> > > The numbers and the anecdotal experience of professional
> > > spin/aerobatic flight instructors are totally at odds with your
> > > belief.
> >
> > So how many inadvertent stall-spins do they get to see under normal
> > conditions?
>
> I'm not sure I understand the question...

When doing aerobatic (or emergency maneuvering) training, the
probability of inadvertent stall is high. In fact, I have
inadvertently stalled several times, and once almost spun, but every
one of those instances was while learning or practicing aerobatic
maneuvers. These are not normal conditions, and in any case the risk
is low because everything is done at relatively high altitude, in an
appropriate airplane, with proper training, etc.

I've also seen one inadvertent stall-spin from the back seat of a
glider. The student was a very low time power pilot on his first
glider flight, and he was practicing thermaling flight. That's what I
mean by normal conditions - when a student is doing routine things and
botches them badly enough to stall and spin.

> Not true -- I routinely demonstrate one variant of the classic skidded
> turn base-to-final

I think skidding the base to final turn AND being slow is pretty
serious mishandling of the airplane. In a glider instructional
situation, it's certain to cause noise from the back seat. Of course
the profile of the average glider instructor is a lot different from
the average power instructor.

> > > And pilots with fewer than either 500 hours total time, or 100
> > > hours in type, are more likely to encounter an inadvertent stall/spin
> > > than to have a genuine engine failure.
> >
> > Why do you keep going back to the patently unprovable? All we know is
> > that they are more likely to have an accident caused by stall-spin
> > rather than engine failure. This tells us nothing about the
> > likelihood of encountering either hazard.
>
> Thos enumbers are from an NTSB study. I'm notmaking them up. Perhaps
> you'd be happier if I prefaced with "Pilots who make it into the NTSB
> database share these characteristics..."

No, the proper preface is "Accidents that make it into the NTSB
database share these characteristics." You have absolutely no idea
what sort of hazard encounters these pilots had that did not end in an
accident. The concept I'm going for here is "The rate of accidents is
not an indicator of the rate of hazard encounters."

> > Now let's consider something else. A pilot who flies 200 hours a year
> > is 10 times more likely to have an engine failure than one who flies
> > 20 hours a year, since engine failure is not under his control. Are
> > you seriously suggesting that a pilot who flies 200 hours a year is 10
> > times more likely to inadvertently spin than one who flies 20 hours a
> > year? I would argue that he is LESS likely to inadvertently spin,
> > since the higher level of proficiency that is a nearly inevitable
> > result of flying a lot and often will make him less likely to miss the
> > rather obvious clues.
>
> You admitted yourself, all flight time is not equal.

Absolutely. It's simply the only reliable measure we have.

> In that regard, I
> would say the pilot who flies 200 hours a year of white-knuckled
> X-country, averaging one power-on landing every 2 hours, who is
> deathly afraid of stalls to begin with and has never spun, and flies
> by the adage "maintain lots of extra flying speed just in case" is far
> more likely to encounter an inadvertent stall/spin in a stall/spin
> critical situation than a pilot who flies 20 hours a year in his
> Pitts, 30 minutes at a shot, performing advanced aerobatic maneuvers
> and averaging 4 gliding landings per hour (my former Pitts partner did
> just this last year). I'd bet on the survival of this Pitts pilot over
> the other one in a similar stall/spin critical scenario.

No argument at all. And unfortunately I've met the 200 hours of white
knuckled XC guy. He absolutely refured to turn off the autopilot in
IMC; I could tell he was extremely nervous when I hand flew his plane
for a few minutes. His landings are all power-on. If he encounters a
spin, I doubt he will survive it. But he's not the norm, either.
Typically when a pilot flies 200 hours a year, he's proficient.

> Perhaps a better gage of a pilot's ability to deal with stall/spin
> critical operations is not flight time, but rather the number of
> landings per hour.

I would say landings per year, and rate power-on and power-off
differently. For that matter, different aircraft rate differently.
In a glider, you're never far from a stall. In fact, I have to wonder
if my experience with students is skewed because so many of them are
glider pilots as well... In a Cherokee, you have to work hard to
stall.

> After all, one trip around the pattern exercises
> many, many critical piloting skills. It would be interesting perhaps
> to do a study with this as the hypothesis -- would this interest
> you???

Sure. Where would you get the data?

Michael