Mailing List lml@lancaironline.net Message #38593
From: rtitsworth <rtitsworth@mindspring.com>
Sender: <marv@lancaironline.net>
Subject: RE: [LML] Re: Fwd: Power Off Emergency Landing
Date: Fri, 17 Nov 2006 20:34:06 -0500
To: <lml>
Robert, etal

You said: "With the MT prop the loss of oil pressure puts the prop into full
feather without any pilot input."

This is only true for an MT FEATHERING or MT COUNTERWEIGHTED prop (course
pitch but not full feather).  A (normal) MT CONSTANT-SPEED will go the other
way (fine pitch) without oil.

Basically the behavior is the same for all "brands" of hydraulically (oil)
activated props.  Counterweighted (and feathering) goto course pitch without
oil, (normal) constant speed goto fine pitch without oil.

The advantage of the feathering is better glide.  The disadvantage is that
if the governor fails on take-off you have an immediate forced landing - at
the worst possible time (even with the engine running).  Feathering props
are also typically heavier.

The counterweighted props are a compromise, offering better glide than a
constant speed prop (but not as good as a feathering prop) and better
take-off failure than a feathering prop (but not as good as a constant speed
prop).  Constant speed props are also typically heavier than a constant
speed prop, but lighter than a feathering prop.

Choices, choices.

Rick Titsworth


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