Engine Dependability

Oops...typo in row 2, column 3. It should be 1075 and not 1901. Sorry.

-Sami

O. Sami Saydjari wrote:

OK. I have gone back through my logs and compiled the following
information on my aircraft.

Since my airplane was born around 10/13/1977, it has had 4 engine
overhauls (including the most recently one that I am having done now).
The Mean Time Between Failure has been 877 hours of operation, 7
calendar years. The most recent failure took place within 318 hours of
the last overhaul. The table below gives the details:

Overhaul 1....10/01/79...826 hrs...2 yrs
Overhaul 2....05/26/85..1901 hrs...5.6 yrs
Overhaul 3....11/18/89..1288 hrs...4.5 yrs
Overhaul 4....04/06/04.. 318 hrs..14.4 yrs.
-------------------------------------------
Average................. 877 hrs...7 yrs

This is a far cry from the 1400 TBO on the first engine
(overhaul 1) and the 1800 TBO on the second (overhauls 2,3 and 4).

If anyone else is willing to post their data, it might make for some
interesting information in a thread.

-Sami

O. Sami Saydjari wrote:

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

On 19-Apr-2004, "O. Sami Saydjari" wrote:

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.


My understanding is that TBO is a recommendation by the engine manufacturer
based upon engineering expectations and service history. The FAA maintains
a system for mechanics to report unusual maintenance and/or component
failure issues. These reports inform the process by which ADs are
formulated, and presumably the information also makes its way back to the
engine, airframe, and/or component manufacturer.

What broke on your engine after only a few hundred hours? Was it a factory
engine or a field overhaul? Was it under warranty? Did your mechanic file
a Maintenance Report or Defect Report?

--
-Elliott Drucker

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)

What broke on your engine after only a few hundred hours?

I will not really know until the overhaulers take it apart. I should
know more in a couple of weeks.

Was it a factory
engine or a field overhaul?

TCM overhauled it.

Was it under warranty?

No.

Did your mechanic file
a Maintenance Report or Defect Report?

We shall see. I will report later, when I know more.

Just to be clear. I am not intending to whine about my particular
failure, but rather express some concern about the lack of actual data
being collected that supports decision-making about dependability of
engines.

Aar
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.


I also looked through service diffciulty reports, but I found it very
hard to really tell whether they were (a) representative of all
airplanes or exceptional to just a few and (b) comparatively any better
or worse than another airplane (or engine). It is not clear how one
uses SDRs as a metric....at least not to me.

my airplane is a 1965. Without going and digging out the logs, the
approximate times are

1991. First overhaul at 2000 hours (almost to the minute...it was on part
135 at the time so overhaul was required). That's 26 calendar years and 2000
hours. I didn't see any other engine work beyond replacing accessories and
normal maintenance before then.

2003. Second Overhaul at ~3125 hours. 12 calendar years, and 1125 hours.
First overhaul was a service limits overhaul with chrome cylinders. Second
overhaul was needed for spalled cam. It had been making metal for about 500
hours, and oil consumption was about 2.5 hrs/qt.

This is an O-540-E4B5. Normally aspirated, carbureted, 260 HP. TBO is 2000
hours

2003 Overhaul was a reman to new limits, new cylinders, new cam, reground
crank and case. about 60 hours so far.


"O. Sami Saydjari" wrote:--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

In article , O. Sami Saydjari
wrote:

EDR,
I am afraid that I beg to differ. You certainly may question the value
of an "average" TBO to decision-making, but you can track the numbers
quite accurately (assuming correct reporting). It would really only
take the cooperation of a small number of overhaul shops, some A&P
mechanics and such.
In the same way, one could question the value of the accident rate of
the "average" GA pilot. Granted that all of us are above average
(apologies to Garrison Keillor), but such statistics can be useful
starting points, for example, to see if trends are improving or if a
given measure is worthwhile. Similarly, average disease mortality rates
are useful for medical treatment, despite no person being average.
I do not mean to beat a dead horse, but I really think it would be a
good idea, from an engineering perspective, to collect and report this data.

Sami,
Find some Pitts pilots who flys Intermediate or Advanced competition.
Ask them what the TBO is on a Lycoming AEIO-360/540.
Ask them how many hours they flew their Pitts doing competition
aerobatics (practice and contests).
The engines are 1200 or 1400 TBO (IIRC).
Most competition pilots overhaul between 600 and 700 hours.
When you go from wide open to closed throttle repeatedly, the engine
experiences higher than normal wear.

In article , O. Sami Saydjari
wrote:

I do not mean to beat a dead horse, but I really think it would be a
good idea, from an engineering perspective, to collect and report this data.

Yes, but unless you know how the engine was consistantly operated, you
have no understanding of why one engine goes 2000 hours and another
only 150 hours.

In article ,
EDR wrote:

Sami,
Find some Pitts pilots who flys Intermediate or Advanced competition.
Ask them what the TBO is on a Lycoming AEIO-360/540.
Ask them how many hours they flew their Pitts doing competition
aerobatics (practice and contests).
The engines are 1200 or 1400 TBO (IIRC).
Most competition pilots overhaul between 600 and 700 hours.
When you go from wide open to closed throttle repeatedly, the engine
experiences higher than normal wear.

The worst engine TBO is on top fuel dragsters. It's something under 10
seconds.

did they do the overhaul?

if not.. then why should they care about the failure... it goes back to the
shop that did the overhaul

JMHO
BT

"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