running on condition

Eagle · Post by **Eagle** » Fri Nov 16, 2007 8:00 pm

Could anybody give me a detailed explanation about the pro and cons of running an engine on condition.
(private reg. C-172)

summitx · Post by **summitx** » Fri Nov 16, 2007 9:01 pm

Well I'm not an ame so hopefully a few of them will jump in here. You need a good ame and use the same one each anual if you can. That way they know the history of your aircraft and can give you good advice. For a private reg you can go as long as your ame will sign off the engin. If it has been properly maintained and is flown regularly you can likley go well beyong the published tbo. Your ame will likely cut open your oil filter could also take a look with a bore scope and you could also have an oil analysis done to check condition of the engin. Not sure what year your 172 is ?? pre 68 likely wont go beyond tbo 68 to 76 if treated well will go well beyond tbo after 76 for a couple of years (h series) are junk. Good luck with it but don't take any chances Your talking to someone who's had an engin failure, not in a 172 (a 185) and its no fun.

Pratt Punk · Post by **Pratt Punk** » Fri Nov 16, 2007 10:22 pm

Airworthiness Notice -B041, Edition 4 - 31 March 2005
Piston Engine On-Condition Maintenance Program Requirements

Available on TC Website. Will provide guidance on what is required.

summitx · Post by **summitx** » Fri Nov 16, 2007 10:30 pm

Excellent pratt punk I was just pounding through my AIM and my old AIP because I know I had seen this schedule.
As I recall its not that difficult monitor oil consumption, scope the cyclinders each inspection, leak down test to specs and perhaps a few other items. Well worth it considering the cost of a rebuild if its an engin with a good reliability record.

624 · Post by **624** » Sat Nov 17, 2007 10:53 am

There is no tbo on small, privately registered piston aircraft. So they don't need to go on condition.

Pratt Punk · Post by **Pratt Punk** » Sat Nov 17, 2007 2:49 pm

624 wrote:There is no tbo on small, privately registered piston aircraft. So they don't need to go on condition.

That is correct.

CAR Standard 625 APPENDIX "C" (6)

"No hard time, including calendar time, between overhauls need be observed in the case of small aircraft reciprocating engines in non-commercial private operation."

However, a large majority of private aircraft owners choose to maintain the criteria of the on-condition program to enhance engine reliability and safety and to retain a certain level of resale value in case the aircraft is sold for use in a commercial environment.

It remains a judgement call on the part of the aircraft owner and the cost associated with it.[/b]

black hole · Post by **black hole** » Sat Nov 17, 2007 4:58 pm

The biggest "IF" with the Lycoming engines is sitting time. If you buy an AC with a low time engine and the last overhaul was 20 years ago chances are that the cam shaft needs replacing. But if you bought a high time engine from a flying school that did 6-800 hours per year you should be in good shape. Cylinders should be changed every 2000 hours.
If you fly at least 25 hours per month every month 5-6000 hours is not unreasonable even with the o320 H engines.

BH

Spinner · Post by **Spinner** » Sat Nov 17, 2007 9:50 pm

the longer you go (calendar and time wise) the more expensive your overhaul may be when you eventually need it.

As said by BH the longer that you less you use the aircraft the harder it is on the engine. If you run the engine fairly regularly and monitor it's condition then you should not have a lot of problems.

black hole · Post by **black hole** » Sat Nov 17, 2007 11:03 pm

If you run the engine regularly and get 4000 hours you can scrap the engine and still be money ahead.

BH

Hedley · Post by **Hedley** » Mon Nov 19, 2007 9:01 am

I once flew a twin with 5500 SMOH on one engine. They just kept changing jugs and accessories. It was flown frequently - as others have said, the hardest thing you can do to an engine is NOT fly it. Nobody bothers pickling engines any more, despite the fact that it costs a tiny fraction of a major overhaul.

You park a Lycoming, the cam is gone, and the jugs are probably rusted, too.

aero-singidunum · Post by **aero-singidunum** » Wed Nov 21, 2007 10:23 am

black hole wrote:The biggest "IF" with the Lycoming engines is sitting time. If you buy an AC with a low time engine and the last overhaul was 20 years ago chances are that the cam shaft needs replacing. But if you bought a high time engine from a flying school that did 6-800 hours per year you should be in good shape. Cylinders should be changed every 2000 hours.
If you fly at least 25 hours per month every month 5-6000 hours is not unreasonable even with the o320 H engines.

BH

Agree 100%, I had H engine 10 years ago at 4500 hrs, not even a cylinder. But did replace lifters every 1000 hrs, and school did use over 600 hr a month, so was very good.