Primarily for general aviation discussion, but other aviation topics are also welcome.
By Deeko01
#1831538
Evening!

We are looking at putting a small group together and one or two of the aircraft we have saw have an engine on condition including one which has flown 1150 hours since the last overhaul which was 25 years ago.

My question is, if the engine is in good condition and compressions are good then how much emphasis would you place on that or would you be minded to say it will need overhauled almost right away.

I imagine an engine that hasn’t been overhauled in 25 years will have a price that reflects that.

The aircraft would be on a private syndicate group that would accept an on condition engine but we have no experience of this.

Any help would be most welcome.

Thank you.
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By Awful Charlie
#1831543
I agree with Andy (but without the bitter personal experience)
Frequent flight is often quoted as a saviour of old engines, but there are so may variables you can't be sure that past treatment will make a silk purse, any more that you can be sure that a brand new engine won't suffer an early life catastrophic failure.
FWIW, non-flown or preserved Lycomings *tend* to get camshaft/follower problems, but as to replace these you have to tear the whole engine down, you would be in a special situation to just replace the failing parts and not do a complete overhaul.
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By Rob L
#1831568
Deeko01 wrote:One of them is an AA5


So on a C of A . In your place I would be severely tempted to walk away, unless the whole aircraft was being sold for £5K, whereby I would take a risk on the salvage, after 25 years.
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By irishc180
#1831579
What most people who don't work on aeroplanes fail to appreciate, is you can just take off a cylinder in about two hours and take a look at the cam and followers etc etc. Without doing that, it is possible to tell a huge amount by boroscoping an engine, ground running it with an optical tacho, doing an air test, compression test and oil analysis. Who rebuilt it and who maintained it tells the rest of the tale.

If you don't know what your doing, the sky is always falling down. If you want to fly an AA5 you can try our one out for free, pm me if you wish.
By riverrock
FLYER Club Member  FLYER Club Member
#1831585
As said, assume the engine is scrap - you are buying and airframe. If the engine runs its a bonus.
Your use of the aircraft will be different to the current owner. That change of use may be enough to bring the engine quickly to the end of its life.
Get a v. good inspection...

We decided to buy a Jodel with fairly high time engine. Flying it for a few years has allowed us to build up the funds to re-engine. It might work for you, or it might not.
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By TLRippon
#1831595
It seems to me aircraft can fly perfectly on condition for many years until you want to sell them, at which point an overhaul is suddenly demanded. The aircraft could fly on for decades more with proper maintenance.
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By GrahamB
FLYER Club Member  FLYER Club Member
#1831596
TLRippon wrote:It seems to me aircraft can fly perfectly on condition for many years until you want to sell them, at which point an overhaul is suddenly demanded. The aircraft could fly on for decades more with proper maintenance.

That's true, but the issue is how much that maintenance will cost, and when.
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By Lockhaven
#1831609
The engine in my aircraft was constructed in 1966 and still going strong, it obviously has had overhauls in its life but has been on condition since 2003, if isn't broken don't fix it.

For the last 10 years the oil pressure and temperature hasn't changed and the compressions are still greater than 75psi
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By MichaelP
FLYER Club Member  FLYER Club Member
#1831610
Has the aeroplane been in a dry hangar or outside in the damp?
How often has it been flown?

An aeroplane that has done 1100 hours over 25 years has done 44 hours a year, but perhaps many more hours in earlier years and a handful of hours in recent years, and then there’s the lockdowns which in my opinion are potentially dangerous to the health of an engine.

I flew a Cherokee that sat outside, did 40 hours a year, little during the winter. Cam lobes and cam followers were corroded, and a cam follower broke up as I was in the climb out... Expensive.
I worry more about Lycoming engines in this regard than any others.

The Continental O-200 used to need a top overhaul at around 1500 hours. One of my O-200s was removed by the engineer as it had 2,796 hours on it, but this was an engine that was used often and its compression and oil pressure were still very healthy...

The Rotax engine is something else.
Had one 912F that continually over heated, after overhaul it still overheated. I suspected there was an internal restriction in the coolant passages...
In Ontario I bought two Katanas, the operators there told me that if I got less than 3,000 hours out of a 912 I was doing something wrong, and they were running the engines on 100LL!

I noticed a 912S being removed from one of the Katanas...
You get less hours out of a 912S compared to a 912F, but I was disappointed. Then the engineer told me it had done 2,700 hours.

An engine that’s flown often is very different to an engine that has sat outside and run rarely, or an engine in a dry hangar. It’s history is important.

Then again if it has been overhauled, was this done by a trusted company or engineer?

Then again there’s the tragedy of G BHRW blown apart on Top Gear, scrapped for its value beyond engine overhaul...
Buy the aeroplane that does the job for you, and if the engine needs overhaul and this exceeds the resale value of the aeroplane, justify it by using the aeroplane and having the confidence in a fresh engine with a warranty.

I replaced engines in my Condors, well above the resale value of the complete aeroplanes, but the Condor is superb at the job it was designed to do, so why wouldn’t I?
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By GrahamB
FLYER Club Member  FLYER Club Member
#1831612
TLRippon wrote:A lot less than a overhaul when one isn’t needed

I think we’re in violent agreement!

The key is to get a thorough pre-purchase inspection done and be prepared to walk away if a sensible price can’t be negotiated.
Last edited by GrahamB on Mon Mar 08, 2021 9:18 am, edited 1 time in total.
By BoeingBoy
#1831613
Given the time frame it is going to be a factor that the last overhaul was so long ago, but to me the deciding factor would be frequency of use and type of storage. If it was inland and always hangered I'd go ahead with a full engine inspection and look to buy.

My 0-360-A4M was first installed in 96. It then shed ferrous metal in 2006 and was zero timed by a very reputable company. Since then it's only done 500 hours and spent most of its time at coastal airfields.

Whilst the engine has always produced good compressions scoring and corrosion was found on all three cylinders two years back and I've replaced all four along with the carburettor which was an old model that should have been changed many years back. (Whilst I know it's bad luck to say this) It's regarded by my maintenance company as being in fine condition and when I requested a dynamic prop balance another company said not to bother as it was one of the smoothest engines they'd ever run.

The old GR24 has now been replaced by continuous monitoring and I would suggest that you look carefully at each years engine run records for trends in compressions and oil pressure etc. Ask the owner to produce the work packs from each maintenance company that did the work. They should still have them to hand.

Get a really thorough pre-buy and if the price is right take a chance.
Edward Bellamy liked this