Real stats on engine failures?

"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

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