Re: ATR Prop Brake ???

From: (Desrt Ratt)
Organization: America Online, Inc. (1-800-827-6364)
Date:         14 Aug 95 03:43:27 
References:   1
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The use of the prop brake enables the engine to be run in "Hotel Mode" for
compressor bleed (used for air conditioning) and electrical loads without
having the expense and weight of an APU (auxiliary power unit).
Obviously the other benefit is eliminating risk of the rotating prop to
ground crew while the aircraft waits to depart the gate.  Downside is
extra weight & additional failure modes for the engine, additional time &
cycles on the main engine, plus it's not as efficient as a dedicated APU.
I'm not sure what other turboprop A/C besides ATR's (with P&W 120-series
engines) have them.