Re: Static from Cross-feed

Date:         13 Jan 97 18:35:32 
From:         Steve Lacker <>
Organization: applied research laboratories
References:   1 2 3
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jfmezei wrote:
> So, if the airport does not supply forced air, wouldn't the aircraft at
> least use ground electrical power to run its fans and airconditioners ?

No, the on-board A/C units aren't electrically powered, with compressors
and refrigerant (aka 'Freon') like a household or automotive unit. To
vastly oversimplify, they operate by bleeding highly compressed, hot air
from the engine compressors or APU, cooling this compressed air via heat
exchangers, and then letting it expand to atmospheric pressure (and thus
drastically cool) into the cabin. The air itself is the refrigerant, and
this method requires that an engine or APU be running. It is much more
cost-effective and lighter weight to do it this way, when such a
tremendous amount of compressed air is readily available, but not overly
efficient on the ground.

Stephen Lacker
Applied Research Laboratories, The University of Texas at Austin
PO Box 8029, Austin TX 78713-8029