wrote in message
...
Mine were limited to shoving the prop ahead turning final (in every
complex aircraft I've ever flown in) at approx 1200-1400 rpm (prop
control previously set to 2300 in cruise) with no change in engine
rpm/prop noise noted.
That's a completely different situation. At that power setting, the engine
didn't have enough power to drive the prop at the selected RPM (2300), and
so the blades were already at flat pitch. Selecting high RPM would have had
no effect, since the governor was already trying to increase RPM, to its
limits (maximum flat pitch).
Next time, pull the prop to *minimum* RPM and see your glide angle decrease.
Have pulled mis-rigged PT6A props to "flat" on short final a couple of
times, have the stained shorts to prove it.
Not sure how that statement fits in to the discussion, but the PT6 governors
work differently from those found on most piston-engine singles.
Before I posted, I called my gov shop buddy to make sure his views
coincided with what I remembered from hanging around in his shop. He
related same, that the gov bench doesn't indicate useable gov pressure
until around 1500-1600 rpm.
You mentioned "gov pressure" in an earlier post, and I still don't
understand what you mean. The force to change the prop blade angle comes
from springs and oil pressure, not the governor itself. All the governor
does is adjust oil valves to control how the oil moves through the pitch
change mechanism.
In any case, as with the others, I've had no trouble at all reducing the
blade pitch even in low-RPM, idle-power situations. I have no reason to
expect I'd have any trouble in an actual engine failure, assuming the engine
continued to windmill and run the oil pump.
Pete
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