AIR CONDITIONING -PRESSURIZATION -SYSTEM TESTS

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D633W101-BEJ  May 05/2002 

AIR CONDITIONING -CABIN PRESSURE CONTROL SYSTEM -INTRODUCTION

Purpose
The cabin pressure control system controls the amount of air that flows out of the airplane. This keeps the cabin air pressure in limits at all airplane operating altitudes (-2,000 through 43,100 feet, -610 through 13,146 meters).
Physical Description
The cabin pressure control system has these components:
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One remote cabin pressure sensor

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Flight deck controls

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Two outflow valves.

Interfaces
The air supply cabin pressure controllers (ASCPCs) provide control, indications, and bit for this system. The controllers also have an internal sensor that they use to monitor cabin pressure. The sensor is used for control and to give an output on the ARINC 629 buses. The ASCPCs are part of the engine air supply system. See the engine air supply section for more information about the ASCPC interfaces related to cabin pressure control (SECTION 36-11).
The remote cabin pressure sensor sends data to the AIMS, the ASCPCs, and ELMS. AIMS uses the remote sensor data as an alternative to the ASCPC cabin pressure data.
EFFECTIVITY
BEJ ALL

The ASCPCs use the remote cabin pressure sensor to cross check data from there internal cabin pressure sensor.
ELMS sends the remote cabin pressure sensor data on the ARINC system buses. ELMS also uses the remote cabin pressure sensor data as an alternative to the ASCPC cabin pressure data.
See these section for more information about the ELMS interfaces related to cabin pressure:
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Passenger compartment illumination (SECTION 33-21)

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Information signs (SECTION 33-22)

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Passenger oxygen (SECTION 35-21).

The ASCPCs usually get landing altitude from the flight management computing function (FMCF) of the AIMS. As an alternative to the FMCF, the flight crew can manually set landing altitude from the bleed air/pressurization panel.
The cabin pressure control system also interfaces with these systems/LRUs:
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ADIRS

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CMCF

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EFIS

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FMCF

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PDF

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OPAS

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AFDS

21-31-00

Page 1 D633W101-BEJ Sep 05/2002

AIR CONDITIONING -CABIN PRESSURE CONTROL SYSTEM -INTRODUCTION

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EEC

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Left (right) WOW card.

See the engine air supply section for more information about the interfaces related to the ASCPCs and cabin pressure control (SECTION 36-11).
General Description
The flight crew sets automatic or manual control of the outflow valves from the flight deck.
Each valve is controlled independently. You can set auto for one and manual for the other.
Auto Control
In the automatic mode, the left ASCPC usually controls the position of the valves. The right ASCPC gives backup control. Automatic control supplies these functions, most important first:
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Controls the cabin-to-ambient differential pressure to a maximum of 8.6 ± .05 psid

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Limits the cabin pressure rate-of-change

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Controls the cabin altitude to no more than 8000 feet (2440 meters)

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Limits takeoff and landing pressure bump

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Controls the ratio of air outflow between the forward and aft outflow valves.

Manual Control
For manual control the flight crew controls cabin rate-of-change and cabin altitude by manually controlling the position of the outflow valves. They use the outflow valve switches to turn on/ off manual control.
Once manual control is selected, the flight crew uses the outflow valve manual switches to control the position of the outflow valves.
EFFECTIVITY BEJ ALL  21-31-00 
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D633W101-BEJ  Sep 05/2002 

AIR CONDITIONING -CABIN PRESSURE CONTROL SYSTEM -INTRODUCTION

EFFECTIVITY BEJ ALL  21-31-00 
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D633W101-BEJ  May 05/2002 

AIR CONDITIONING -CABIN PRESSURE CONTROL SYSTEM -AIR SUPPLY CABIN PRESSURE CONTROLLER

General
The air supply cabin pressure controllers (ASCPCs) control the pneumatic system and cabin pressure. These functions operate independently.
Location
The left and right ASCPCs are in the MEC on the E1 and E2 racks.
Physical Description
The ASCPCs have test and cabin pressure sense ports on the front. The test port is for in-shop service. The cabin pressure sense port lets the controllers monitor cabin pressure.
The ASCPCs use operational program software (OPS) that you can load.
　
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