Incorporating a used engine

[CarlOrton]

Hi, All; I understand the ramifications of what I'm about to ask, but was looking mainly for actual experiences from other builders.

Has anyone ever placed a used certificated engine as-is on their project, without rebuilding it? (well, removing the data plate to de-certify it...) As an example, I've been able to find mid-time engines salvaged from hail-damaged planes. No prop strike, etc. Aside from changing the oil/filter, checking the plugs, etc., and assuming good compression, why not just slap it on your airframe and go with it?

[Sam Buchanan]

Hi, All; I understand the ramifications of what I'm about to ask, but was looking mainly for actual experiences from other builders.

Has anyone ever placed a used certificated engine as-is on their project, without rebuilding it? (well, removing the data plate to de-certify it...) As an example, I've been able to find mid-time engines salvaged from hail-damaged planes. No prop strike, etc. Aside from changing the oil/filter, checking the plugs, etc., and assuming good compression, why not just slap it on your airframe and go with it?

I've done it twice, an O-320 (Cessna 172) on the RV-6 in 1998 and more recently an O-200 (Cessna 150) on the Fokker replica. I left the data plate on both engines. Just keep in mind it is a bit of a roll of the dice because you don't have first-hand knowledge of the internal condition of the engine. If the engine has been inactive or infrequently flown in recent years there may be issues with corrosion. But if you purchase the engine at a good price where you can afford overhaul if necessary down the road, it can be a reasonable option.

[DaleB]

Why would you remove the data plate?

[CarlOrton]

Why would you remove the data plate?

OK; was just going by memory here, and that sometimes fails.... I was under the impression that even if installed in an E/AB aircraft, the engine still had it's certification, and would therefore have to have only "approved" parts otherwise it could be deemed unairworthy. Personally, I don't care if the plate's on it or not, as long as I can add any ol' nut or bolt I want from the aviation department of Lowes (and I would never do that; except to perhaps attach a ground cable, and even then I'd think about it...)

[nrpetersen]

My opinion is that I would rather use a tired old but still running OK engine on a first flight than a freshly overhauled one. The well used engine won't surprise you with infant mortality failures, and can better survive poor baffling & other cooling problems. Corrosion problems in the cylinders (assuming a reasonable inspection) won't cause a catastrophic failure - just high oil consumption. Once you got the other test flight wrinkles straightened out, go ahead and overhaul it. But expect the engine to run hotter until it is broken in. Just make sure the outside is reasonably clean so it can cool, and so you can spot oil leaks.

[CarlOrton]

I view that as a valid aspect that I know about, but hadn't considered in this context. Thanks for the reminder!

[Frank Giger]

My opinion is that I would rather use a tired old but still running OK engine on a first flight than a freshly overhauled one. The well used engine won't surprise you with infant mortality failures, and can better survive poor baffling & other cooling problems. Corrosion problems in the cylinders (assuming a reasonable inspection) won't cause a catastrophic failure - just high oil consumption. Once you got the other test flight wrinkles straightened out, go ahead and overhaul it. But expect the engine to run hotter until it is broken in. Just make sure the outside is reasonably clean so it can cool, and so you can spot oil leaks.

This can bite one in the rear end, though.

One of my EAA brothers bought what was billed as a "moderately high but sound" engine and had to perform a landing under stress on flight number three. Subsequent tear down showed it was in much worse shape than advertised; while the compression was good, the main bearings looked like termites had their way with them.

I'd say a tear down inspection before first flight is probably prudent if the engine isn't a completely known quantity.

[cub builder]

I could tell several horror stories about "used" engines that looked great in the logs but were junk inside, but to answer the question; Absolutely not. Did that once 30 years ago. Nearly cost me my life when that "low time" engine packed it in at night in the mountains some 79 hours later. That "low time" engine was full of obsolete and superseded unairworthy parts, one of which failed. I made myself a promise then that I would never again have an engine on my plane that I didn't tear down and inspect first. If you want to fly behind an unknown pile of junk, have at it.

I am familiar with Frank's friend and his engine as well. That story was typical of the "good used engines" that look great in the logs being bought and bolted on to Homebuilts. Rarely does it work out good. A few I know have done OK with a used engine, but most have ended up with a pile of junk parts and an overhaul in the first 150 hours or less. Just bite the bullet and do the overhaul up front so you know exactly what you have on the front of your plane. Breaking in an engine just isn't that difficult, even on a new plane. Or if you buy a manufactured engine, the hard part of the break-in has already been done in a test cell under controlled conditions.

The last used engine I bought (O-320) for my SuperCub project I found when I was asked to do a logbook review of the engine for someone that wanted it for their aircraft. Man, it looked great on paper at a very reasonable price and I recommended it as a good buy based on a logbook review that showed nothing irregular over the life of the engine. Life took another turn for him, and he couldn't use it. I asked if it would be OK with him if I bought it for my project and he agreed. First run engine a few hundred hours short of run out. Perfect engine to bolt on the plane after building, run a couple of hundred hours while I recover from the initial cost of building. I was really tempted, but decided to tear it down for inspection anyway. I found: cracked crankshaft, out of spec and cracked case, corroded cam followers and spauled cam, 4 cylinders that had been overheated so bad the cylinders were blue inside and all 4 heads cracked. I am so thankful that my customer didn't buy it on my recommendation. And I had nothing more than a pile of junk parts in need of a lot of new parts to build an engine.

[CarlOrton]

While tempting, I'm thinking that if it weighs on my mind every time I'm flying, it's not worth it. Definitely worth a tear-down.

[Frank Giger]

The thing is that a tear down is not a rebuild, unless necessary, and inexpensive. And with the right guidance isn't that difficult.

My initial thoughts on the logic that it's better to put an unknown on the aircraft in order to be sure it flies okay than spend the money and find the aircraft is a dog in flight was that it was kind of screwy were validated.

But hell, I strapped a VW engine on my plane so I never faced the financial challenges of a certified engine. I was poor mouthing the fact that I had to spend 200 bucks on a new crankshaft and another 200 on a new prop hub when I flipped my bird only to be politely told to hush up...and got a few prices for minor things on an O-200.