I know: the sensible answer is “everything”!
But I’ll tell you something: I worry least about engine condition. The reason is because I can repair the engine (up to an overhaul) and then I’m done.
What worries me is problems that make expensive repairs irrelevant (like unrepairable airframe corrosion after an overhaul). What also worries me is avionics (the labor in figuring out what is wrong is unbelievable).
But most of all, it’s airframe. If the airframe is clean, your repairs (some day) will end. Your repairs have incremental value.
In looking at old planes, I have come to assume that an overhaul is required. I see that the avionics need to be replaced. But I only want to go to the trouble if the plane is clean when naked.
How many older planes are truly clean? If they are clean, are the immortal? Can they live to 100 years?
WP agree entirely it is all about the airframe, and the accompanying airframe log books. Ideally a low time, clean airframe with a relatively run out engine. Cosmetics should be OK, although for tube and fabric, fabric condition is obviously important.
The type should be simple with a clear market following – some types hold their value much better than others: 182P/Q/R/S, Warrior/Archer 3, 206, DR400.
While I can understand avionics being an issue for turbine equipment, for the sort of IFR flown by piston equipment, over investing in retrofit glass etc is not a good investment (new standby/EFIS aside). 8.33 NAV/COM plus PBN/B2 IFR GPS is all that is required. The majority of aircraft will soon have Mode S and 8.33, and a second hand IFR GPS (BK 89/94/Garmin 300/400/Apollo) is cheap to slide in.
if the plane is clean when naked
Naked airplanes…. never come across one before.
The only one thing you need to worry about, is the lad behind you in the que with money in his paw.
Thats all :-)
Should change the heading to used plane. You won’t worry about corrosion and engine condition on a new plane.
My take: the most important is finding an engineer with a lot of experience on the type in question, who knows the type-specific diseases and can do a pre-buy inspection properly. Also, it’s better if the engineer inspecting the actual aircraft and the one checking the logbooks for compliance with all ADs and other binding regulations are one and the same person.
If possible, the pre-buy inspector should be the guy doing the first annual.
Unless your time is very valuable compared to your available money, do a first inspection, including logbooks, yourself. Then discuss it with your planned maintenance guy. You’ll learn a lot from the logbooks. But don’t trust them. Local chat can be useful.
As regards the “guy behind you with cash”, that’s usually a risk worth taking.
BUT: after buying a Bolkow Junior last year, I heard from an aero club member that their CFI phoned just after me, and was very upset to find it sold.
It is certainly true that the engine is a “known max risk” i.e. your liability is limited to the overhaul cost. Well, not unless the crankshaft is corroded or otherwise unusable; then the engine becomes a throw-away and your least bad option is usually a “remanufactured” engine – e.g. here.
Whereas heavy corrosion or other damage on airframe parts can cost you much more. However, that should not happen unless the prebuy was negligent e.g. the guy probably never even removed the inspection covers. And this does happen… I saw one such not long ago.
The likelihood of corrosion of anything, especially important (expensive) bits, depends on the age of it and where it had been sitting. You need a prebuy done by someone who is working for you and preferably who is likely to be maintaining it under your ownership. Some corrosion is trivial to fix (you can even patch the skin) and some isn’t. Well, often it is but not legally, and this applies particularly to things like bushes and bearings which are trivial to replace but cannot be replaced legally, under EASA… see e.g. here.
Avionics is difficult because almost all engineers (mechanics) have no idea about avionics. So you need to find someone who knows the particular boxes and who can functionally test the lot. Especially an autopilot and all its modes. Lots of people have sold a plane with autopilot problems, successfully
I bought my aircraft without a pre buy inspection and I paid the price.
My set of lessons learned consists of:
- First, definitely do a pre buy inspection and by an AP of your choice (preferably who has experience on the type) and definitely not the seller’s home mechanic. A prebuy inspection should be with proper checklists and check points in between so that as a buyer you can decide to quit the deal or continue paying the AP for his/her time for the remainder of the pre buy inspection. For example if corrosion is found, it may already be end of the negotiations and pre buy within the first hour.
- I would be extremely careful about low time engines and paying a lot of money for it. Especially the ones between 0-250 hours or so, as the most important things for an engine are how /where it was overhauled, how it was broken in in the first 20 hours and how regularly it was flow. I would buy mid/high time engine (good compressions, regular oil analysis results, low oil burn and clean filter) at low price and reserve cash for near future overhaul to have it done myself and be the first pilot to break it in.
- Have the seller to fly the aircraft for you, sit and observe. This often reveals a lot about how the aircraft was treated in general and how the engine was managed. Often easily reveals bad habits, lack of knowledge etc. See if the seller starts the engine roaring at 1500rpm during a cold start.. thats already a bad sign.
- Avoid flight school aircraft. We’ve all been students. Just remember how you used to land when you first started now think of hundreds of other students doing the same thing to this aircraft you want to buy and fly your family in. A big no and I dont care if the aircraft was even used in CPL/ATPL training.and the standard stuff like no accidents, complete logs, documentation and clean bill of AD/SB compliance. Also please make sure the documentation is not fake. Especially have important and expensive ADs verified physically for example if logs say “teflon hoses installed”.. check to make sure they are really teflon.
lastly.. buy an aircraft. There is nothing like being a pilot and owning one. The learning curve is just incomparable to anything you can ever learn by flying in clubs. It is just amazing being involved in your aircraft’s maintenence and to develop trust.