So after talking about it on here for friggin years, I'm finally ready to buy a plane. I have a really good partner lined up. Every plane I seem to find has had its last overhaul in the mid 90s, and 25-30 hours a years. So while the total hours are low, the engines haven't really been run that much. I know that type of usage is "average" but it worries me. Rightfully so, or am I being silly? Also, can most mechanics do a borescope inspection during a pre-buy?

Thanks!

Jesse

PS - Please don't paint your plane god-aweful colors. You are spending a lot of money, do it tastefully. When you go to sell, I lose interest, and my wife puts the insta-kabosh on it!

what type of planes / engines?

Check these first before purchasing...

* insurance costs (even if you do not)
* SB, AD, SDR listing for make, model
* request FAA records from OK CITY, 337 etc. and anything they can tell you about it
* consider title insurance I know a guy that got burned on a lean for $3000 it get ugly if the courts want the aircraft for any reason
* find a decent person who will do annuals and sign offs ahead of time if possible and get a per buy inspection.
* the AC "Plan Sense" is the FAA's guidance on owner ship and you should read until memorized.
* STC listing from FAA, might find a game changer STC you like

Go though the logs if there some. Try to estimate want needs to be done to it for continued airworthiness ie. Mags at 500hrs, recurring ADs etc...

Just a few thoughts this morning before going surfing (the first South Swell has arrived!). Situation awareness is everything!

I'm getting a prebuy and title insurance on anything I buy. I've been looking at C150s, C140, Cherokee 140s, C172s, and C170s. So basically O-200, O-320, or C-145/300.

I have a mechanic I trust lined up. I rent planes from him now, and it is the only rental place I've been to that have the planes meticulously maintained. I also get quotes on minimum amounts of labor for annual inspections for any type considered. He gives me an honest estimate. Not $400 annuals. Basically, it is the engine condition I am concerned with. I know big bills come along, but I'd like to avoid a $20k overhaul year one.

This may sound terse but, get a differential compression tester, timing box, and other items for a basic 100 hour inspection. Learn to use them from a trusted A&P. Then "you can make better post decisions from a earlier bad decision". Hope that made sense.

We all make compromises and mistakes. But, it is how you can recognize them early and have the funds and knowledge to not let them stop you from having fun!

A good mechanic can usually give you a very accurate number on when major work or an overhaul will be needed. I have estimated numbers to owners and have been pretty close.

But, not all mechanics can or will honestly tell what's left in an engine. Not rocket science, these engines have been around forever. No big deal.

A differential compression tester is a waste of $$$ for an owner. They are not even REQUIRED for an annual inspection. I've had engines that'd pass a diff compression check but were junk inside. I called Lycoming on one of those engines and the Tech Rep laughed when I told him compressions. Said the only reason we still do diff compr checks is because that's what we've done for decades.

In any case, not necessary for an owner.

To actually answer one of your questions, yes, you can ask a mechanic to bore scope cylinders during a pre buy. If the owner says no, RUN, do not walk away.

Continentals tend to be more tolerant of being parked. Camshaft is on the bottom, so typically bathed in oil. So, on those borescoping cylinder bores may be good enough.

Lycomings, on the other hand, have cam on top, and that's typically what goes ugly in an engine that's sat idle for long stretches. Cam and lifter spalling will cost big bucks down the road. Your mechanic may be able to pull one cylinder part way off during pre buy to inspect cam and lifters, but you can't inspect them all from one cylinder. An owner MIGHT not be comfortable with your mechanic pulling a cylinder, either.

Sorry, but an infrequently operated engine is pretty much the rule in aircraft for sale, and to be honest, there is really no way to guarantee an engine is corrosion free. It's a little bit of a crap shoot.

If previous owner flew it regularly, but just not much, you may be golden. Ones to watch out for is one that's sat for months or worse without being run at all.

If that mechanic you're working with is as sharp as you say, have him do a thorough pre buy, and express your concerns, then let him inspect what he feels is appropriate.

MTV

Yes to the Lycoming cam problems in seldom run engines. This is especially true in high humidity areas. Airplanes parked in El Paso or Tucson fair better than those in Ft. Meyers or Portland Oregon. I doubt that visual inspection of the cam will guarantee anything. The nitriding is so thin that it can be compromised with little visual impact. Once spalling has started it's all over. An oil analysis log of tests over time will tell you plenty but a single test with no context doesn't reveal much. "Oregon Maule" has a thread back there someplace all about experience with a low time engine with a cam wasting away quickly. Big buck overhaul.

Flight schools can run these engines for thousands of hours over TBO because they are run every day. They are great engines, they just have this one Achilles heel.

Continentals like the 0-470 have 1500 or 1800 hour TBO but I have known several with 2200 hours plus still running strong with regular flight and ongoing oil analysis.

All of this by way of OPINION mind you. Your experience may vary.

Thanks guys. I was aware of the camshaft differences as well. That's why I feel a little bit better about one of the continental powered planes. Seems their bottom ends may be a little less prone to issues from not a lot of running compared to lycomings. I will get a borescope on the cylinders and hope for the best. Maybe try and find a buyer that had regular oil tests done.

I've also heard someone say that you should try and find every reason not to buy an airplane. That's my plan.

From Personal Experience:
1. Borescope the cylinders. I bought a plane with perfect compression tests that spun the center main bearing 11 hours later. Borescope revealed two different types of pistons, 3 flat topped one, one domed piston and 2 different generations of valves.
2. If the last 10 annuals found no problems with a plane older than 10 years, they weren't looking. Walk away.
3. If it's an O-200 or O-300 pull the valve covers. Continental sold some cylinders around 2000-2004 that didn't have a bushing on the rocker arm shaft. The hardened steel shaft would wear out the aluminum blocks it's mounted in and start spinning. These cylinders were only good for about 100 hours. So they added a set screw, this brought it up to 200 hours. So they eventually added a bolt through the shaft. If you don't find either a bronze bushing on that shaft, or a bolt through it, plan on buying new cylinders soon.
4. if it's spent any time in Florida or similar humid tropical areas. Walk away. If it's not showing any corrosion, that just means they cleaned up what was visible.
5. If the avionics are old, check to make sure they're still maintainable. Some older radios no longer have new parts available.
6. With any older aircraft, unless it's had a complete rebuild recently, consider the purchase price to be a down payment. The maintenance costs will exceed it in just a few years.

7. Consider an experimental. They're typically the best bang for the buck, and most of the common ones are every bit as well designed as a certified plane. And probably newer than any certified plane in your price range. Just make sure you find someone familiar with the design to look it over with you to ensure it was well built, and doesn't have any dangerous deviations from the original design.

mtv wrote:A differential compression tester is a waste of $$$ for an owner. They are not even REQUIRED for an annual inspection. I've had engines that'd pass a diff compression check but were junk inside. I called Lycoming on one of those engines and the Tech Rep laughed when I told him compressions. Said the only reason we still do diff compr checks is because that's what we've done for decades.

In any case, not necessary for an owner.

To actually answer one of your questions, yes, you can ask a mechanic to bore scope cylinders during a pre buy. If the owner says no, RUN, do not walk away.

Continentals tend to be more tolerant of being parked. Camshaft is on the bottom, so typically bathed in oil. So, on those borescoping cylinder bores may be good enough.

Lycomings, on the other hand, have cam on top, and that's typically what goes ugly in an engine that's sat idle for long stretches. Cam and lifter spalling will cost big bucks down the road. Your mechanic may be able to pull one cylinder part way off during pre buy to inspect cam and lifters, but you can't inspect them all from one cylinder. An owner MIGHT not be comfortable with your mechanic pulling a cylinder, either.

Sorry, but an infrequently operated engine is pretty much the rule in aircraft for sale, and to be honest, there is really no way to guarantee an engine is corrosion free. It's a little bit of a crap shoot.

If previous owner flew it regularly, but just not much, you may be golden. Ones to watch out for is one that's sat for months or worse without being run at all.

If that mechanic you're working with is as sharp as you say, have him do a thorough pre buy, and express your concerns, then let him inspect what he feels is appropriate.

MTV

Good work.

Bear_Builder wrote:7. Consider an experimental. They're typically the best bang for the buck, and most of the common ones are every bit as well designed as a certified plane.

Make sure to take into account insurance costs and availability of people who would service it (if you don't want to do that yourself).