Selecting a Used Engine

Hi, All;

I know a lot about auto engines; was a certified auto tech before I received my degree; have assembled many.

I don't know much about aircraft engines other than the obvious stuff / mostly accessories / owner maintenance items.

So it dawned on me: If I'm wanting something like an O-200 for my experimental aircraft project, I know I'll want to tear it down for inspection. I'm aware that there are overhaul manuals all over eBay. But, aside from textual descriptions of engines for sale, how do I pick one? I know it's not a good indicator to rely only on hours SMOH, etc., and some known salvage yards at least will state prop strike or not, but aside from that, and whether or not the accessories are included, is it just a crapshoot? Any words that would tip one off (aside from a prop strike) that the case might need to be line-bored, for example? Are there a good set of questions one should ask to get some indication of the quality of a used engine?

This is going to sound terrible, but assume any engine you buy second hand needs an overhaul unless it has a detailed log with it...and then tear it down to make sure.

Certified engines are 1940's tech, btw. The parts are crazy expensive, though.

I bought a local salvaged O-200 that I later found it to have a cracked crankshaft flange at radius.
Never heard of line boreing of aircraft cases, other than VW.
The salvage yard might only offer money back in some circumstances, if the as is item doesn't meet your desire. You still pay freight, I guess. Ask?

Carl, unless it's advertised as freshly overhauled or just removed from service with records, it's a crap shoot. If you get logs, at least you'll have a record of history. Some planes that are wrecked sit outside for months and I've seen engines that were full of water, dirt, etc. because openings were left uncovered. Inspect if you can. You can always ask for a list of what (if any) accessories are included.
Several yrs ago we found a C-150 for sale that had been flipped by windstorm. The engine was low-time and unharmed so we bought the plane and removed the engine for use in another airplane. Turned out to be a much better deal money and time wise than rebuilding a runout.

Case, crank, rods, cylinders - can usually be reconditioned for service at reasonable rates. I guess the worst scenario would be having to spend ~$4k to replace the crank. Since the engine does not need to meet type design, you have more options to build a satisfactory engine.

Thanks, Marty; Your info is pretty much what I was looking for. I know going-in that I'm going to tear it down for at least an inspection, but was just wondering if there were any tell-tale things I should look for to hopefully avoid getting something where I need a new case and crank (at the least).

When I bought a used engine, I assumed that anything I bought was going to require a major overhaul. I assumed it would need at least four new cylinders and a cam, and shopped accordingly. I did get a guarantee from the seller that the crank would be serviceable, but other than that there were no guarantees. I avoided anything that had a prop strike. I ended up buying one from a known reputable salvage yard (Beegles in Colorado). The O-360-A1A I bought had not been run since the mid 90s. I had it shipped straight to the local engine shop, where I had them tear it down, clean it up and NDT the parts. I got lucky -- all four cylinders were bad (cracks around the exhaust ports), but the cam and crank were good, no corrosion or other problems. Aside from the cylinders, everything was in good shape.

Remember -- log books only tell you what the owner and mechanic wrote down in them.

Dale (specifically), others in general;

Well, I found and bought a salvage O-200. From Beegles, Dale. Funny, I wasn't looking specifically at Beegles, but just happened upon it. Logs back to 1972 (was in a C-150J). All accessories included. Had a prop strike, but dye penetrant showed no cracks and runout was .001". Still, I'm going to tear it down and send-out the parts for full examination, measurement, etc.

It has 1173 SMOH, and all 4 cylinders were replaced (with no ID of what kind, or if new or overhauled) 549 hrs ago.

So, now, my main question is: how do you determine if you need to a) overhaul or b) replace with new cylinders? I won't be able to run a compression check until after reassembly (or can I?). Assuming of course, that visual inspection reveals no eroded seats and NDT shows no cracks. I'm prepared to replace all 4 with new Superiors, but obviously don't want to toss money at them if they're serviceable.

Secondly, since this will go in a Zenith, do I need to adhere to ADs if the data plate remains on the engine?

I really don't know all the details about inspecting the cylinders. I'm fortunate enough to have a really good engine shop local to me -- Central Cylinder at KOMA. They showed me where the exhaust ports were eroded and cracked, so that was it. They told me the cylinders could be repaired and rebuilt, but it would end up costing within $50/cylinder of just buying new jugs.

As for compression, that's a matter of the condition of the valves, seats, rings and bores. All of those are easily inspected and repaired or replaced.

I've done my share of engine work, but I know my limitations and comfort zone. I'll tear apart and put back together the engine in my car, motorcycle or scooter. Not the airplane. I don't want to be flying behind an engine some guy built as his first try at it (me). Just like I wouldn't weld my own fuselage. Maybe if I were working with someone who had a lot of experience and was checking everything I did as we went along.

Quote:

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Originally Posted by CarlOrton

Secondly, since this will go in a Zenith, do I need to adhere to ADs if the data plate remains on the engine?

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Here is guidance from AC 39-7D:

b. Non-TC’d Aircraft and Products Installed Thereon. Non-TC’d aircraft
(e.g., amateur-built aircraft, experimental exhibition) are aircraft for which the FAA has not
issued a TC under part 21. The AD applicability statement will identify if the AD applies to
non-TC’d aircraft or engines, propellers, and appliances installed thereon. The following are
examples of applicability statements for ADs related to non-TC’d aircraft:

(1) “This AD applies to Honeywell International Inc. Auxiliary Power Unit (APU)
models GTCP36-150(R) and GTCP36-150(RR). These APUs are installed on, but not limited to,
Fokker Services B.V. Model F.28 Mark 0100 and F.28 Mark 0070 airplanes, and Mustang
Aeronautics, Inc. Model Mustang II experimental airplanes. This AD applies to any aircraft with
the listed APU models installed.” This statement makes the AD applicable to the listed auxiliary
power unit (APU) models installed on TC’d aircraft, as well as non-TC’d aircraft.

(2) “This AD applies to Lycoming Engines Models AEIO-360-A1A and IO-360-A1A.
This AD applies to any aircraft with the listed engine models installed.” This statement makes
the AD applicable to the listed engine models installed on TC’d and non-TC’d aircraft.

I suggest NOT removing the data plate. Even with the data plate removed, you still have a TC'd engine. It's a TC'd engine with a missing data plate. As long as it's installed in a non-TC'd aircraft. you can do what you want with it since it doesn't have to comply with type design. Install your own exhaust, change carburetors, regrind the cam to a hotrod profile, install roller rockers. whatever suits your fancy. Can do all that even with the data plate installed. If an AD came out that applied to the engine and includes those installed in non-TC'd aircraft, you should comply but you should do that even if you remove the data plate.

Of course, applicability to your specific product is determined by you the owner/operator. For example, if an AD was issued requiring inspection of the rocker arms for cracks and you have your cool billet machined roller rockers, the AD would be N/A. Parts not installed.