Right on. In the big radials, the feathering was done with
a feathering button that powered a feather pump, so there
was no issue of feathering with the prop control. But in
the light twin, the prop lever control rpm and when it is
moved through a detent, the governor dumps the oil and the
prop feathers. But you can set the engine to an idle of
about 1000-1200 rpm and then feather the engine and let the
prop go all the way. But at idle the engine won't feather
because the stops will prevent the prop from feathering.
You do a feather check at 1500 rpm because that assures the
stops are retracted with enough rpm to allow the blades to
get into the feather range. You can run on the detent ass
long as you wish, but unless you want the engine to shake,
shudder and need to have the prop unfeather during the start
attempt, don't let the rpm drop below 1,000 rpm during the
feather test. If you have unfeathering accumulators it is a
one shot deal to get started...with the prop control still
in feather, prime and engage then starter, when you start to
get a little oil pressure and the engine is firing, move the
prop control full forward and hope you have enough oil
pressure from the governor to move the prop blades out of
feather. This is an emergency technique, much better to
have a mechanic use blade boards to manual turn the blades
out of feather.


--
James H. Macklin
ATP,CFI,A&P

"Dale" wrote in message
...
| In article
,
| "Peter R." wrote:
|
|
|
| Leave it there a moment? Hmmm, when I transitioned to
the Bonanza, my
| first constant speed prop aircraft, I was told by the
very experienced CFI
| not to let the RPMS drop too much during this
pre-takeoff item or it would
| place a high load on the engine (I believe his analogy
was like shifting a
| car into 4th gear while driving at 25 miles per hour).
|
|
| At the power setting for runup I can't see it being a
problem.
|
| On the radials on the B-17 and B-24 part of the check was
to bring the
| prop controls to the low RPM position to check the low RPM
pitch stop.
| We wanted to see the RPM hold at 1200.