Re: 737 NACA inlet with moving parts?

From:         "David G. Davidson" <>
Date:         28 Oct 96 03:06:35 
References:   1 2 3
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David Lednicer wrote:

>What you are looking at is the ECS inlet (air pack inlet) on the
> 737.  Usually, you throttle the flow into an inlet by changing the
> exhaust area, but someone at Boeing decided to throttle the inlet
> instead, which never works too well.

What's being talked about here is the RAM air system of the ECS. The air
pack inlet can't be seend from outside the airplane.

The RAM air system on the 737-200 and -300 modultates the inlet and exit
doors to maintain 230 F at the compressor discharge. On the ground the
doors are wide open.

There is a deflector in front of the inlet door that opens (extends) for
ground operations.

>Lockheed made the same mistake on the L1011 ECS inlet.

They may have come from the factory with operating inlet doors, but they
also came with operating exhaust doors. The inlet doors have been
deactivated and airflow through the RAM duct is controlled by the
exhaust doors.