Posted for "George/Shirley Shattuck" <kloop@plantationcable.net>:

For what it is worth, here is my experience with my prop during the initial
test flights.

A friend mechanic overhauled a runout O-320 D1G  for me.  He installed an
incorrect crankshaft plug.  It was basically a freeze plug without the
flanges that the overhaul manual calls for.  During the initial flight and
several subsequent flights, the prop would check out fine on the ground, but
at flight speeds the prop would not govern and the RPM would exceed the
limits.  By reducing throttle I was able to keep the RPM at around 2900 and
below.  After much dollars and jumping through hoops, including sending off
the governor, putting pressure gauges on the prop governor (rear mounted)
nothing worked.  With the prop off, a flashlight in one hand and a beer in
the other, I discovered (peeking up the crankshaft) that the crankshaft plug
did not look like the one on the engineering drawings.  With a screwdriver
and a hammer I popped the thing out of there and sure enough, it was a bogus
part, installed a little cattywhompus, allowing oil to leak past it into the
crankcase under air loads.  That condition did not allow sufficient pressure
to remain to regulate the prop pitch in flight.  Under ground test loads it
worked just fine.  The correct part was $1.85.  When installed the prop has
been normal in all respects ever since.

George Shattuck
N320GS
Greensboro, Georgia