OK, why do they cover the prop?

"Dale" wrote in message
...
It kept the prop from dissipating the heat applied to the engine by my
pre-heater.

Interesting. I didn't realize so much heat could be transferred through the
crankshaft. I guess it makes sense though...the prop does have a lot of
surface area, so heat flow is easy to have.

On the bright side, with the engine pre-heater pumping heat through the
prop, you didn't have to worry about frost.

Pete

"Peter Duniho" wrote in message ...
"Dale" wrote in message
...
It kept the prop from dissipating the heat applied to the engine by my
pre-heater.

Interesting. I didn't realize so much heat could be transferred through the
crankshaft. I guess it makes sense though...the prop does have a lot of
surface area, so heat flow is easy to have.

There's an AD against Lycomings of 160 HP and over using
fixed-pitch props that demands an inspection of the internal bore of
the front end of the crank. This end stays pretty cool when the engine
is running, even in warm weather, and the low temp causes condensation
to form in that bore, which is open to the crankcase, and the water
and oil form acidic sludge that eats pits in the bore and weakens the
crank. I think there has been only one failure so far, though a lot of
cranks have been found with the pitting. Constant-speed props use that
bore (plugged off at the rear) to feed oil to the prop, so it's not a
problem. And I suppose a composite or wooden prop would be much
better, not wicking away so much heat.

Dan