Old engines, future?

[Tom Downey]

Tom,
I wouldnt expect a DER to know about the inteaction of valve tip and rocker materials, would you? And the difficulty is also relative to the type of engine. An A-65 or Franklin should be a lot more straigntforward than a TC Wright engine. Dont get me wrong, I love making parts for old engines, however I have seen a lot of poorly made parts that were due to the individuals lack of understanding and knowledge about the part they were trying to duplicate. Take a crankshaft for instance. Sure you can measure it for dimensions, thats simple, materials can be scanned with a GS or an SEM ( both is better ), thermal metal treatments can be estimated. However what about mechanical treatments like shot peening? What size was the shot? What pressure? What angle? How long? How many times? This is where you would make multiple parts, and try various types of shot peening, cut up the cranks and compare them to a cut up original. Under the eye of an expert metalurgist this would still only give you a "best guess". This project undertaken by a group of people experienced in crankshaft design would at least have a decent chance of working. Done by anyone else would be a risky business. So what does this come down to? It aint gonna be cheap!

Most cases during overhaul of an early engine we do not see exotic materials, You may in some post war big radials, but the Jake, Warner or Continental have nothing fancy to cope with, the cranks and cam rings are usually in good shape, if not they have methods to metalize back to standard and regrind, most we see are over sized cylinders and worn pistons both are getting difficult to find and expensive.

The P&W 985 / 1340 are still factory supported so no big deal there.

designing isn't a big deal in the daily grind of GA

[Aaron Novak]

Metalizing crankshafts??

[Tom Downey]

Metalizing crankshafts??

could you tell which had been and which had not? besides we have bearings that go -.008" under on the crank main bearing. plus these old cranks aren't even nitirded.

I have 2 on my bench now that had a spun bearing, and will clean up at -.006" and will have fitted bearings ready to go this week. their value? $15-$25K but neither is for sale.

It's never the ability, it's always the cost.

[Tom Downey]

More pictures of the Warner 165

[David Darnell]

Well, I'll take a little offense to the comment about the "young kids" not knowing anything about the antique engines. I'm a "old fart" and haven't messed with a radial, V engine, Inline, etc since A&P school 30 years ago. Would hate for someone to come to me because of my being older- the "kid" has had less time to forget everything!

[Aaron Novak]

could you tell which had been and which had not? besides we have bearings that go -.008" under on the crank main bearing. plus these old cranks aren't even nitirded.

I have 2 on my bench now that had a spun bearing, and will clean up at -.006" and will have fitted bearings ready to go this week. their value? $15-$25K but neither is for sale.

It's never the ability, it's always the cost.

Hey Tom,
To the naked eye maybe not, however there are ways to easily tell. Personally, building up of a crankshaft by any means is a scary deal to me, especially in the repair world. I have never seen a repair shop that used anything but plasma arc spray welding, thermal spray welding, spray and fuse, or some form of arc welding for building up non aviation crankshafts, and none of those processes impress me. Going undersize I dont see as anything abnormal. I guess I was just supprized to hear anyone building up aircraft cranks. I assume that by building up a crank it is considered a major alteration?

[Tom Downey]

[QUOTE=Aaron Novak;6361]Hey Tom,
To the naked eye maybe not, however there are ways to easily tell.

In the field? in a running engine? the only thing that would trigger any investigation of that type, would be a smoking hole, But no worries, we would do this legal if and when we need to.

I assume that by building up a crank it is considered a major alteration? [QUOTE]

Most definitely
(2) Powerplant major repairs. Repairs of the following parts of an engine and repairs of the following types, are powerplant major repairs:
(iii) Special repairs to structural engine parts by welding, plating, metalizing, or other methods.

Remember when I said it is always the cost, not the ability? the cheaper route to repair an under sized crank, is to gain authority to go under size and manufacture a bearing to fit.

[Aaron Novak]

So have you been using built up cranks? Or was that just a hypothetical? If you have been using them, what engineering basis did you use to determine if the repair was suitable?

[Tom Downey]

So have you been using built up cranks? Or was that just a hypothetical? If you have been using them, what engineering basis did you use to determine if the repair was suitable?

You are asking for intellectual property that will not be posted on the internet.

When you bring the engine in for rebuild, we will discuss what needs to be done, how it is to be used and where you are going to get the parts.

READ FAR 21.9 (a) (5)

[JimRice85]

I know of a shop in San Antonio that metalizes cranks for about anything. He has done a great deal of work in various racing applications and has had no problem. I know he has also metalized some Franklin cranks for folks, but there is no paperwork on the cranks. He has also straightened some bent crank flanges for experimental applications and they have run to TBO without issue.

The ability is there.....gaining approval, that is a whole new ballgame.

He once had a FSDO Inspector show up at his shop demanding a bunch of stuff and to inspect the shop. Since he is not a pilot nor A&P and his business has nothing to do with aviation, he told them to go pound sand. When she protested he was working on airplane engine components, he told here, "I work on crankshafts. I don't know what they go to. A customer brings me a crank and specs. I build/rebuild it to the spec and give it back. I don't know and I don't care what it comes from." They never came back. Of course, if you have any aircraft part which goes through there, I'm sure the FAA would condemn them. I know some experimental folks have used him extensively and his results have been outstanding.