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Date: Sun, 19 Jun 2011 19:56:11 -0400
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Subject: Full feathering prop
From: Dan Ballin <dballin@gmail.com>
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One point about terminology.  There is a difference between full
feathering props and counterweighted props.  When oil pressure drops,
both go to low RPM (coarse pitch), but full feathering will obviously
go into full feather position and counterweighted goes close.  Full
feathering need an accumulator (read extra weight complexity) to get
out of feather were counterweighted will generally windmill.  The
interesting thing ( and I only have what I have been told) is that the
difference in drag/glide performance is not that significant.

I wanted a counterweighted prop so when the engine quit it would go to
best glide configuration without my input.  I ended up with an MT
because of weight and at the time Hartzel didn't have a spinner that
would fit the Legacy.  I think the down side is the issue raised that
if the engine is still running and the oil pressure is low, the prop
will go to coarse pitch - not the best, say on take off.  The other
issue is that I think with training, one can get the prop lever back
to low RPM fairly quickly.  Counterweights do increase weight and cost
so is it worth it?  Not sure.

Like everything else, this is a compromise and you just need to know
the correct procedures for your install.

Dan
N386DM
hopefully flying this summer