Real stats on engine failures?

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 . com...
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 om...
(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

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 . com...
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 om...
(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" 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.

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.