Salvaged Aircraft Crank?

I'm looking at a wrecked RV. Wood prop O-320, I don't know the rest yet. It flipped over the nose while idling. For value, I'm assuming the crank will be bent or cracked. Safe bet? Firewall is likely wrinkled and I'll be looking for that and cracked gear/engine mounts. Anything else?

As a comparison, I bought an O360-A4M out of a 2002 Piper Archer with around 1100 on the engine since OH in 2014 (flight school). The airplane was on the ramp when a wind storm came through and destroyed the airplane.

I do not know if the prop was damaged but am assuming it was and will follow the Lycoming guidance to do a prop strike inspection. This entails sending the crank and case out for NDI inspection. I fully expect no damage but the peace of mind of *knowing* it is good is what matters to me.

Raymo said:

I do not know if the prop was damaged but am assuming it was and will follow the Lycoming guidance to do a prop strike inspection. This entails sending the crank and case out for NDI inspection. I fully expect no damage but the peace of mind of *knowing* it is good is what matters to me.

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This is what I did. My plane was tied down and not running when the tornado flipped it. Just to be sure, I sent my crank to Aircraft Specialties Services and the case to DivCo, both in Tulsa. They did a Magnaflux inspection on the crankshaft and a zyglow inspection on the case. Both parts came back looking like new.

We do Jabiru engine prop strike inspections all the time, and we send out the crank and rods to Aircraft Specialties Services. Most of the time the crankshafts pass the run-out and Magnaflux inspection, even if the wood prop is totally trashed. But there's always that 1% chance that its not ok. Unless you tear it down, you just don't know. As a buyer don't assume anything is ok unless you can see it and measure it.

KatieB said:

This is what I did. My plane was tied down and not running when the tornado flipped it. Just to be sure, I sent my crank to Aircraft Specialties Services and the case to DivCo, both in Tulsa. They did a Magnaflux inspection on the crankshaft and a zyglow inspection on the case. Both parts came back looking like new.

When you buy the airplane, make sure the price assumes that the engine is for core value only, because you never know.

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For bid purposes, it's bent. For reality purposes, like Katie says, get it inspected and tagged. *If* it was idling, and had a wooden prop, I'd bet it's serviceable. 2 cents of free Internet advice.

BruceMe said:

For value, I'm assuming the crank will be bent or cracked. Safe bet?

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Not at all. A tear down is in order but the crank may well have survived this. I rebuilt an O-200 last year under similar circumstances; they have notoriously fragile cranks but this one checked out just fine. Cost for magnaflux and inspection was about $75 at Aircraft Specialties.

Of course, for bidding purposes, the crank is trash until proven otherwise.

Me too.

Bryan is on the track with this one. You can't be sure tell you check it but with a wood prop it is hard to bend a crank flange. You would be wise to build the cost of a tear down, inspection, and crank replacement into you pricing of the aircraft. If the seller dose not want to do the inspection. Then keep your fingers crossed that you make that money back after the perches. Most crank bends with wood props happen when you really stand one on the nose and dig the nose into the dirt with some good throttle input and the airplane moving pretty quickly. That is one of the nice things about a wood or plastic prop. The prop takes the energy and you save the engine 9 times of ten. I may have to go up on Bryans rates here a little thou, so thats my 4 cents worth. Yours, R.E.A. III #80888

One thing to remember about cranks and prop strikes is that there are a couple of things that can go bad - one is that it gets bent, so yes you need to dial the flange. The other is that the sudden stop jars the bolt that holds the rear gear on the crankshaft, loosening it.

Then at some point in the future, the bolt comes off, the gear comes off, and things get really quiet. This is why you can't JUST dial the flange after a strike - you have to check that bolt, which requires pulling the accessory case.

I think the OP has the right idea - consider it junk unless proven otherwise, and price accordingly.

Low Pass said:

For bid purposes, it's bent. For reality purposes, like Katie says, get it inspected and tagged. *If* it was idling, and had a wooden prop, I'd bet it's serviceable. 2 cents of free Internet advice.

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Did you see the article in SA about the guy who was flying low in a J3 with a wood prop and he hit a bunch of corn stocks? The engine hickupped and kept on going. Later that day the crank broke! Previous damage? Dunno. I always heard that with a wood prop or a light strike at idle you could be ok but that is all guess work. The only advise that is guaranteed to be right is to bite the bullet and pull the engine.

I have a friend who is an accomplished Automotive Engineer with particular experience in engine design. He has been a member of the "core" design team on more than one "clean sheet," new engine design.

I own a 3000A Magnaflux. My Magnaflux "mentor" did NDT for Lockheed Skunkworks for 30+ years. Questions to both reveal that Magnaflux is good only to about 3/8" deep. After that, both confirmed only industrial X-ray has the ability to discern deeper defects.

What's really problematical about prop strikes, whether wood, Aluminum or composite, regardless whether the prop hits something "hard" or is just "slowed" -contact with "high grass" is enough. The critical (essential!) fact is whether the contact occurs just as a cylinder fires off, since (as he put it)

"The loads go to Valhalla!".

And defects deeper than 3/8" frequently occur.

He is as thrifty a guy as I've come across, but his experience compels him to conclude if he ever experienced a prop strike in his C-182, it would be a mandatory tear down with X-ray testing.

FWIW, YCMV (Your conclusions may vary)

mjb

RV-6 Salvage

So I just got back from first hand inspection...

Few things;

- Logbooks burned in a house fire soon after
- O-320-E3D. "looks" good with accessories mid-time
- I tracked the crank-flange by eye... I couldn't perceive a wobble, but all that means is that it's not "very bent".
- Firewall is straight, including all mounts and stringers
- Entire tip-up canopy is trashed
- Fuselage and wing spar are straight. only crumpled aluminum is superficial, non-structural, no big wrinkles.
- Gear "look" ok, but bent into and destroyed the left fuel tank
- Left gear/engine mount is ripped out at the top of the gear leg (not the firewall)
- Panel is very bland... $3k maybe.

I have a price with the guy, in case others are reading this, I will keep it private, but no firm commitment, I wanted to do some math. I know RVs backwards and forwards, but I'm having a tough time on this deal.

For anyone to buy this engine as an "aircraft engine", without logs, it needs to be torn down and retagged. I may do that myself. I'm not sure what to do.