O-320 crankshaft question for the engine guru's.

pierre smith · #1 10-19-2012, 03:16 PM

A friend of mine is starting to rebuild an O-320 for a -9A that folded its nosegear, (He's an A&P/IA) folding the aluminum prop.

The crank dialed OK and no cracks but the shop said that the thrust face is .003" under and they can't yellow tag it. It only has 150 hours since it was rebuilt, so that is likely where the problem started.

What would you engine guys do? Buy a good serviceable or new crank or use it as is? (Dumb question, no?).

Thanks,

rocketbob · #2 10-19-2012, 03:21 PM

Sounds like someone screwed up grinding it. I would use it. The thrust face dimensions aren't that critical IMO.

Also he can look into putting in a thrust face washer. http://www.eci.aero/pdf/02-2.pdf

DanBaier · #3 10-19-2012, 05:00 PM

For experimental, I'd probably use it but I'd check on the install that, with the undersized thrust surface, that you don't wind up with the oil slinger making contact with the engine case. (I think the tolerance there is .002 - .009.) Also, although probably okay, check clearances on the crank journals & case. (Make these checks in both right & left sides of the case.)

Dan

LifeofReiley · #4 10-20-2012, 02:28 PM

Will be fine... Fly it.

agirard7a · #5 10-20-2012, 05:03 PM

I'm no expert but I just rebuilt an 0320
with a very experienced AP. I learned the importance
of these thrust face measurements. He needs to put
The crank in the case and pull it forward until it hits the
main bearing surface and does not hit the oil slinger surface first or at all
For that matter. If it does, maybe some clearance could be milled into the case
surface. Divco could answer that question. Or maybe the washer
solution sounds even better. The shaft has to hit its main bearing surface on that thrust face before it rubs or hits the oil slinger face! This in my opinion
From the little I know would be a major problem and I'm sure
Any AP would agree.