Real stats on engine failures?

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

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

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

"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

"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.

"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

"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.

(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

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)

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