The International Cessna^® 170 Association

I came across an O-300C with an 8 hole crankshaft (from an A?). It has been sitting in a temperature controlled room in a maintenance school but has no oil in it. The school is closing and getting rid of everything so I can get this engine for free. It has no logs and the ID plate is practically unreadable. No one has any history on it except for a tag that reads "for training purposes only". Can such an engine be sent for a complete overhaul and be recertified? Used for parts that can be certified? I'm thinking about that crank. Or is it just a very large paper weight. I figure at worst I can practice taking it apart and learn a thing or two about these engines. Worth the hassle? What do you guys think?

If it's free, I'd grab it and figure out the answers to those questions later. With the scarcity of parts these days, it's better off in your hands than the trash.

Already in the process of grabbing it
They also have a small very light weight 400 hp Allison turbine. Who's looking for short field performance?

If you can read a serial number on the engine data plate then everything else can be inspected, repaired or replaced and a new log book created.

Grab it.

"For Training Purposes Only" might be an indication the engine has been in a fire or other circumstance that forbids it's use in certificated aircraft.

What is known about it: It was a teaching aid for training only, and so marked.
Unless re-certification shops are advised of the engine's known history...that is - it was prevously a teaching aid marked "For Training Purposes Only" .... then I feel that it's unwise and possibly less than honest to simply submit the parts for inspection and re-use in a certificated airplane.

Well there you have it. The cup is half full or perhaps the cup is half empty. You have now gotten pretty much both sides of the fence.

I can't imagine what the difference would be if the parts sat on a shelf in the dark or if they where viewed and held in the hands of students IF and this is a BIG IF they pass inspection and are certified as airworthy parts.

If the data tag is legitimate and has a readable legitimate serial number, it alone is worth something.

The difference would be WHY they were suitable only for training purposes.

Ordinary inspection methods utilized to return previously airworthy parts to service may not be adequate to determine why unairworthy training-only parts are not suitable for certificated aircraft.

If one has not noticed the recent spate of Lycoming crankshafts which were improperly heat treated and/or included vanadium in the alloy...and which subsequently were determined unairworthy, then perhaps one is not thinking about the various subtleties which might condemn a fine-looking part to "training purposes". I can think of several reasons: Involvement in a fire is one of them. Porosity is another. Welding (to return an unairworthy, cracked crank to visually appear normal for the purposes of training only).... is another. (Although such parts are normally engraved in some indelible manner so as to permanently identify them as unairworthy.)

I have in my possession two complete sets of valve springs. One set is airworthy (or actually, they are "serviceable")... and another set is not airworthy. The second set has been "red tagged". If I remove the red-tag and place those springs on a training-purposes only engine that is later inspected by visual means and the previous history of those parts are not passed on to an inspecting authority and theyp are placed in service.... you get the idea.

Any parts which have previously been identified for unairworthy purposes such as training only... should be so considered. And extraordinay inspection procedures may need to be performed if they are considered for return-to-service. In other words.... they are for training purposes only!

As my original maintenance-mentor once said to me, "What part of "No" don't you understand?"

Guess that means I will use it to teach myself how to take an engine apart and practice putting it back together. Thanks all for your input.

So George tell us why the springs are not airworthy that an inspection would not uncover?

I can't think of anything that could be done to engine parts that would render them unairworthy that a proper inspection wouldn't uncover.

I've always had a hard time with the word NO specially if I don't understand why.

While I agree with Georges concerns, many times aircraft and aircraft parts are donated to schools "for training only" to avoid liability issues. It would be a good idea to get a hold of one of the instructors to find out what they used the engine for if anything or was it donated and never used at all. Then a Bruce said, give it a good inspection.

N9149A wrote:So George tell us why the springs are not airworthy that an inspection would not uncover?

I can't think of anything that could be done to engine parts that would render them unairworthy that a proper inspection wouldn't uncover.

I've always had a hard time with the word NO specially if I don't understand why.

I thought I gave a couple of examples, Bruce. I know a welder who can weld a cracked crank, polish it out, and you'd never know it. Not by Zyglo. Not by Xray. Not by the kinds of inspection normally assigned cranks. I once watched him to weld up some virtually extinct early Baron spinners ( a decidedly unapproved thing to do ) and 9 years later they are still undetectably still in service.
Jim Wildharber has seen his work as well, and I'm sure he can attest to the quality of his work. (I once saw a 1/4" thick piece of aluminum angle to which he'd butt-welded the foil from the back of a piece of chewing gum! The guy is incredible.)
I'm not saying the described engine is not capable of being returned to service...I just don't want anyone getting hurt either physically or financially.
If it's intended to return that engine to service in an honest fashion, then .... What is wrong with telling inspectors the known history of that engine? (It was once marked for training purposes only.) Unless the inspector knows that history, he may not utilize appropriate inspection techniques to determine it's true state of airworthiness.

using George's valve springs as an example, say they were in a fire and lost their temper - to inspect them for servicability not knowing their history you're going to check their spring-ability (there's a little spring-checker doodad for that) and you're going to measure their height.

if they pass those rigorous tests, ONCE, they're considered good to go.

now install them in the engine, and run it - they get compressed a bunch of times (I'm too lazy to do the math) and the spring tension is soon gone, as is the spring height, and then your valves aren't working as advertised.

kind of like the old adage about spark plugs - "drop it once, drop it twice" (throw it away). maybe it's not visibly broken, but it probably is stressed and will fail in service.

besides, if that old O300 is anything like the "training engines" I had to play with in A&P school most of the parts will be junk and not meet servicable limits anyway. but if the oil pan isn't rotted out, well perhaps you have found gold even so.

Well I never said hide the fact it was a "training" engine.

I hope you didn't think I was picking on you, or anyone in particular, Bruce - just sharing my meager brain droppings to be chewed up by the group

I usually assume that whatever I contribute will spur somebody on, and perhaps I'll learn something new in the process

HA there is no worries about being picked on here with me.

The whole idea of the forum is an exchange of ideas. Would be pretty boring and we could have ended it years ago if all we had was Joe Expert spewing out "the way" to do everything and then all the Joe Followers saying yep yep yep.

And besides that, if you were reading carefully we have learned where to go if we need a piece of chewing gum foil butt welded?