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Constant speed propeller

Asked by: 3466 views Student Pilot

why does constant speed propeller is kept in course pitch while shutting downthe engine ??

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2 Answers

  1. Lucas on Aug 11, 2012

    uh I don’t think I understand the question, but know that different engines use different governor systems to keep the propeller at its current blade angle. Some of them use engine oil to push the blade to low RPM and high angle of attack and a spring + air or nitrogen to pull it back and some the opposite. All of this is controlled by fly weights that spin with the propeller. If the propeller stops rotating so the the fly weights. Again most POHs will tell you to put the prop lever all the way in before shutting down, so always refer to your checklist to find the correct procedure for your airplane. Finally on turboprops the blades are usually in auto feather mode so shutting down the engine will cause the blase to go into feather position allowing for the lowest amount of drag possible on the dead engine prop in the case of an engine failure.


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  2. Matthew Waugh on Aug 11, 2012

    Generally speaking it doesn’t go to coarse pitch when shutting down.

    Most single engine planes it goes to FINE pitch – and it does this because there’s a large spring always trying to drive the prop to fine pitch, and oil pressure is used to counteract the spring as needed.

    On most multi-engine planes the prop goes to feather (which I suppose is the most extreme form of coarse pitch, so maybe that’s where your question comes from). Same thing, spring drives it that way.

    This is because on a single engine plane you don’t need (or generally have) the complexity of a feather position, and fine pitch gives less resistance during an engine start. On a multi-engine plane, in the event of a loss of oil pressure you want the prop to go to feather for minimum drag.

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