Re: ATR Prop Brake ???

From: (NADIR)
Organization: Megaweb
Date:         14 Aug 95 03:43:26 
References:   1
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  or MIME structure wrote:

>  I recently flew a short leg on an ATR aircraft.  I noticed when the crew
>  started the right engine (couldn't see the left) the prop was held in
>  position by some kind of brake.  The engine ran at gound idle for a
>  few minutes before the brake was released.  When it was, the prop
>  spooled up real fast.

>  When we shut down, it was obvious the prop was stopped with some kind
>  of brake, while the engine continued to run.

>  My question...  How many turboprop aircraft are equipped with a "prop
>  brake", and why?

I personally know that the Saab 340, Atr42, Atr72 and some of the
Brasilias are equipped with prop brakes.  The reason is it allows the
crew to run the engine to power the aircraft.  Many of the smaller
airports do not have provisions for ground power for the turboprops.
More importantly, most airports lack cooling/heating units that can
fit a turboprop.  One other thing, on quick turnarounds, waitng for
the electronic navigation equipment to spool up (which is usually done
after the engines are started) can add significantly to the turn
around time.  Thus, to keep the passengers comfortable and the
batteries from dying, the crew engages the prop brake.  This allows
the Air Cycle Machine to cool/heat the cabin and the use of electrical
power will not drain the batteries. Hope this clarifies things for ya

Loco Hombre