"Dennis O'Connor" wrote in message ...
Piston props (that i have flown) don't feather during shutdown...

It's tough to diagnose a problem on a complex system like a feathering, prop
without being hands on, and without knowing the details of the feathering
mechanism of the model of prop involved, but my initial inclination is
still that it is governor or hub, not engine.... Since then I took a quick
look at the commanche prop hub, and they have a pair of locks that prevent
the blades from feathering when the rpm is below a certain rpm... Those
locks are stuck open or damaged... However, the blades still wouldn't
feather as long as the engine has enough oil pressure for the piston to
overcome the feathering spring... Since he specifically said he had oil
pressure at idle I still am very suspicious that the prop governor has an
internal leak after it gets hot...

snip

The last couple of years that I spent "in the business" I was
seriously spoiled.
All I had to do was walk 75 feet across the ramp to the prop shop
w/attached governor overhaul facility.

The gov shop had two machines, one kept with pristine "new" oil for
checking/setting overhauled governors only, the other with
"serviceable" oil, used for ops/function checking as-removed
governors. I couldn't run one myself, but saw 'em used quite often. As
you would expect, "hot" oil was used when operating the governors.

Back to the PA30 in question, I'm pretty sure that the props installed
will have compact hubs, opposed to steel hubs (with external blade
clamps and external pitch stops). On these props, the locks are
internal, working in the sorta the same fashion (weighted plungers
w/springs), engaging a notch in piston rod (connects the piston to the
yoke that twists the blades) at low/no rpm to prevent feathering on
shut-down.

As you've pointed out, a recip feathering on shut-down (or feathering
causing the shut-down) is not a "normal" situation, neither is the
lack of governed oil pressure at low rpm.

In this situation, I would have gone next door and asked the prop boys
if they could squeeze me in for a "dome job", stopped in the gov shop,
look to see if anything was bolted onto the #2 gov machine and
borrowed the gov pad plate.

Then, with the engine "hot" woulda popped the nose bowl and the gov,
installed the plate, used a differential compression tester to check
the gov-to-prop circuit, plugged it, hooked a direct reading gage to
the gov oil supply port and run that sucker noting the pressure
supplied to the pad.

Pretty simple then to carry the removed gov over and beg the gov dude
to throw it on the machine, if the machine had been "warmed up" that
day, would take about five minutes to wring the gov out.

Depending on hangar space, would probably then yank the prop to get
the dome pulled off and the locks looked at, addressing any other
issues discovered as needed.

E.T. to properly diagnose 2 hours skipping no aspects of "normal"
propeller/govenor ops. Repair time/cost variable as to what was found.

Have had various incidents over the years where a prop feathered on
shut-down. 9 times out of 10, a very careful re-start and shut-down
would result in normal ops. Often would happen again shortly
thereafter. If it feathered "twice" the prop got repaired, end of
story.

BTW, I wouldn't bet that an engine would continue to run at a "normal"
idle setting with the prop feathered, but then again I've never had
the opportunity to try it...

TC