Re: Cabin Pressurization

From: (TriStar500)
Organization: America Online, Inc. (1-800-827-6364)
Date:         13 Oct 95 02:06:32 
References:   1
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>But the question is still: is this regulation a component of the
>*pressurization* system?  Does it respond to user commands or as a
>byproduct of what the pressurization controller is trying to do?

The pack valve is controlled only by the pack switch (and some protective
circuits), so no, it's not part of the pressurization system. Of course,
if the valve is closed there is no pressurization system.

Without a properly operating air conditioning system there is no
pressurization system. Many 727's (engines at idle) can't maintain the
cabin on descent with one pack operating - too many leaks in the pressure
vessel. Push up the power and everything's fine.

The MD80 has a 'Low Flow' light on the pressurization controller. When
this light comes on, it means that the Pressurization Controller has
decided that there is not enough air entering the cabin. Air Conditioning
and pressuriztion work together.