Engine Dependability

"Michael" wrote:
TBO's are usually about 2000 hours, but I don't actually
know anyone with more than 2000 hours of
piston GA experience who has not had an engine failure.

Pardon me, Michael, but there's something puzzling about this statement,
to me. (I know only one pilot with over 2000 hours (~8,000), and he's
never had an engine failure, but that's not what puzzles me). I know
three airplanes that have gone to 2000-hr. TBO two or three times
without an engine failure. Mine went 4500 hours without one before I
bought it. Isn't that equivalent to four pilots' going 2000+ hours each
without an engine failure? How do you account for the unsettling
experiences of your acquaintences?
--
Dan
C172RG at BFM

"Dan Luke" wrote
Pardon me, Michael, but there's something puzzling about this statement,
to me. (I know only one pilot with over 2000 hours (~8,000), and he's
never had an engine failure, but that's not what puzzles me). I know
three airplanes that have gone to 2000-hr. TBO two or three times
without an engine failure. Mine went 4500 hours without one before I
bought it. Isn't that equivalent to four pilots' going 2000+ hours each
without an engine failure? How do you account for the unsettling
experiences of your acquaintences?

Don't know. Were these perhaps small, 4-cylinder, carbureted,
normally aspirated low compression engines? In my experience, most
engine failures seem to occur on engines that are large, 6+ cylinder,
injected, turbocharged, high compression, or some combination. I only
know one person who had a failure with a Cont O-200, one with a Lyc
O-320, and none with a Lyc O-360. All engines are clearly not created
equal.

I think there's some self-selection going on - most pilots who stay in
GA past 1000 hours (except those who spend all their time in the right
seat of a primary trainer) tend to move into higher performance
airplanes where the engines are less reliable.

I believe something like 10% of piston engined Malibus have
experienced inflight engine failures. I would also guess that the
rate of failure in C-150's is at least an order of magnitude lower.

Michael

did you find out the reason for your engine failure yet ?


"O. Sami Saydjari" wrote:

Greg Copeland wrote:

On Mon, 19 Apr 2004 13:53:36 -0600, Newps wrote:


"Greg Copeland" wrote in message
news


Well, I guess that puts us back to the original question. I, like the
orginal article's author, thought historical statistics were used to
establish TBO numbers. If no one is tracking this information, where do
the TBO numbers come from? Insurance liability statistics from wrecks?

TBO comes from two places.

1) Marketing

2) A Guess


LOL! Is anyone else bothered by this? I guess it's not really saying
MTBF, it's just saying, your engine is ganna be tired when it hit this
number. So, I guess that really isn't all that bad after all.

I, for one, prefer to base my decisions on facts instead of
speculations. How do they know the engine will be tired after x hours?
What does tired mean? The only thing that would be meaningful to
owners is probability of failure at X hours.

It does not seem that collecting the data and calculating MTBF would be
that hard.

I sure hope the engineers who designed the engine did not use the same
attitude with respect to the components they used! "Crankshaft A is 20%
cheaper than Crankshaft B? Well, who cares, everyone knows that
everyone just makes the reliability numbers up anyway. Let's use
Crankshaft A." Arg!

Everyone I have talked to who has this engine in their turbo arrows always
say to not fly over 65% power, if so you will not make it to TBO, the
exception is those that have an intercooler installed.
I only fly mine at 65% power, so far no problems in the year I have had it.


Aaron Coolidge wrote:

O. Sami Saydjari wrote:
: OK. I have gone back through my logs and compiled the following
: information on my aircraft.

snip
I think you may find that the TSIO360 engine is considered one of the
least reliable engines out there. This is what's keeping my from buying
a Mooney 231. I did some research into the "Service Difficulty" reports
that the FAA tracks, in concert with A&P mechanics, and it seems like
the engines just devour cylinders. The SDR info is available on the web.

From reading many ads for 231 airplanes I have seen most engines have
a top overhaul at 800 or so hours, and a major overhaul at 1600 or so
hours.

--
Aaron Coolidge (N9376J)

Not yet. Awaiting word from oerhaul shop. I will report back as soon
as I know anything.

-sami

Jeff wrote:

did you find out the reason for your engine failure yet ?


"O. Sami Saydjari" wrote:


Greg Copeland wrote:


On Mon, 19 Apr 2004 13:53:36 -0600, Newps wrote:



"Greg Copeland" wrote in message
news



Well, I guess that puts us back to the original question. I, like the
orginal article's author, thought historical statistics were used to
establish TBO numbers. If no one is tracking this information, where do
the TBO numbers come from? Insurance liability statistics from wrecks?

TBO comes from two places.

1) Marketing

2) A Guess


LOL! Is anyone else bothered by this? I guess it's not really saying
MTBF, it's just saying, your engine is ganna be tired when it hit this
number. So, I guess that really isn't all that bad after all.

I, for one, prefer to base my decisions on facts instead of
speculations. How do they know the engine will be tired after x hours?
What does tired mean? The only thing that would be meaningful to
owners is probability of failure at X hours.

It does not seem that collecting the data and calculating MTBF would be
that hard.

I sure hope the engineers who designed the engine did not use the same
attitude with respect to the components they used! "Crankshaft A is 20%
cheaper than Crankshaft B? Well, who cares, everyone knows that
everyone just makes the reliability numbers up anyway. Let's use
Crankshaft A." Arg!

Jeff, I have been flying mine at 65% power....and I have an
intercooler. -sami

Jeff wrote:

Everyone I have talked to who has this engine in their turbo arrows always
say to not fly over 65% power, if so you will not make it to TBO, the
exception is those that have an intercooler installed.
I only fly mine at 65% power, so far no problems in the year I have had it.


Aaron Coolidge wrote:


O. Sami Saydjari wrote:
: OK. I have gone back through my logs and compiled the following
: information on my aircraft.

snip
I think you may find that the TSIO360 engine is considered one of the
least reliable engines out there. This is what's keeping my from buying
a Mooney 231. I did some research into the "Service Difficulty" reports
that the FAA tracks, in concert with A&P mechanics, and it seems like
the engines just devour cylinders. The SDR info is available on the web.

From reading many ads for 231 airplanes I have seen most engines have
a top overhaul at 800 or so hours, and a major overhaul at 1600 or so
hours.

--
Aaron Coolidge (N9376J)

Jeff wrote in
:

Everyone I have talked to who has this engine in their turbo arrows
always say to not fly over 65% power, if so you will not make it to
TBO, the exception is those that have an intercooler installed.
I only fly mine at 65% power, so far no problems in the year I have
had it.

I don't think it is so much a matter of what power as what temperature.
Reducing power helps with the temps, of course, so...

Watching the JPI EDM float around under various conditions, it's easy to
see how the cylinder temps can get out of hand, even at 65% power. The
engine is somewhat tightly cowled, no cowl flaps, and comes (originally)
with a fixed wastegate.

The Merlyn helps a lot on that, especially here in Texas (where takeoffs
are from almost sealevel and ambient temps may well be over 100F -- fun
to notice your oil temp already reading before you start the engine). I
like to keep my CHT's below 400 or so, even in climb (and more like 330
for cruise). But only a few times, usually a LONG climb at gross, have
I needed to cruise climb for temperatures (I may do so anyway, but
that's just for efficiency).

I don't have an intercooler, and don't have any problem at 75% power, or
even higher (when LOP) during cruise. Interstingly enough, the highest
EGT readings will be at lower power, down around 55%, where 1550+ may be
common (CHT's will be low). And during a climb sometime, try this
experiment - try both 65% or 75% power, vs. full power. I'll bet you
will find that climbing at 41" is a LOT cooler (both CHT and EGT) than
climbing at cruise power.

-----------------------------------------------
James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
-----------------------------------------------

"O. Sami Saydjari" wrote in message ...
I talked to TCM today to register that I am the new owner of one of
their engines. Just in passing, I mentioned that their engine failed
recently within a few hundred hours after major overhaul. They seemed
completely uninterested in knowing this fact. I asked if they kept
actual statistics on actual dependability of their engines. She said
that they did not, to the best of her knowledge. That seems quite odd.

Where do they get TBO numbers from. I always assumed there was some
serious historical statistical date to back these up. Does anyone keep
these statistics? Perhaps A&Ps report such failures? Overhaul shops
maybe? I sure hope someone is tracking the information.

-Sami
N2057M, Piper Turbo Arrow III

I supect that in the past there were manufacturers who did studies to
convince the FAA that their engines could be expected to go 2000 vs
their competitors 1200 or 1500, and used this as a selling point. Now
noone has any interest in changing it.
--
Gene Seibel
Hangar 131 - http://pad39a.com/gene/plane.html
Because I fly, I envy no one.

James M. Knox wrote:

: I don't have an intercooler, and don't have any problem at 75% power, or
: even higher (when LOP) during cruise. Interstingly enough, the highest
: EGT readings will be at lower power, down around 55%, where 1550+ may be
: common (CHT's will be low). And during a climb sometime, try this
: experiment - try both 65% or 75% power, vs. full power. I'll bet you
: will find that climbing at 41" is a LOT cooler (both CHT and EGT) than
: climbing at cruise power.

James, this agrees with what the Mooney people say. They recommend 2700/41"
(or whatever full power is, if you've got an intercooler) for climb, using
airspeed and cowl flaps to adjust engine temps. The theory being that you
will be in the climb for a lot less time, I presume. When you say 41" is
a lot cooler, are you increasing airspeed or maintaing the same airspeed as
in a 75% or 65% climb?
--
Aaron Coolidge (N9376J)

yes I know, you have all the goodies that are suppose to extend the life of your
engine.

"O. Sami Saydjari" wrote:

Jeff, I have been flying mine at 65% power....and I have an
intercooler. -sami

Jeff wrote:

Everyone I have talked to who has this engine in their turbo arrows always
say to not fly over 65% power, if so you will not make it to TBO, the
exception is those that have an intercooler installed.
I only fly mine at 65% power, so far no problems in the year I have had it.


Aaron Coolidge wrote:


O. Sami Saydjari wrote:
: OK. I have gone back through my logs and compiled the following
: information on my aircraft.

snip
I think you may find that the TSIO360 engine is considered one of the
least reliable engines out there. This is what's keeping my from buying
a Mooney 231. I did some research into the "Service Difficulty" reports
that the FAA tracks, in concert with A&P mechanics, and it seems like
the engines just devour cylinders. The SDR info is available on the web.

From reading many ads for 231 airplanes I have seen most engines have
a top overhaul at 800 or so hours, and a major overhaul at 1600 or so
hours.

--
Aaron Coolidge (N9376J)