My A&P is doing a field overhaul on an O-540 (he used to own an engine
shop, and did our overhaul back in '02), and he showed me what happens
to a plane that isn't flown often.

Two valve lifters (the things that rides on the camshaft) have faces
that look like someone took a hatchet to them. The cam lobe that rode
on this valve actually isn't too bad (although it didn't pass spec, so
they're getting a new camshaft), but only because it wasn't flown
enough to completely destroy it before they found a cracked case,
which necessitated a tear-down.

This plane (a Lance) sat for years, then was flown only very
occasionally, and then sat for another nine months while the owner
fought to get his medical back. By the time he finally got it back,
the engine was toast from inactivity.

My A&P's diagnosis: Rust built up on the face of the cam, the lifter,
or both, after all the oil had run off over time. Starting the engine
then put microscopic scratches in the face of both, and started the
process of deterioration.

Scary thing is that the engine ran fine (other than the prodigious
amounts of oil emanating from the cracked case) -- the owner never
knew his engine was beating itself to death internally...

Doctor's orders: FLY OFTEN!

:-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"