Installation of the Cabin Pressure Controller (CPC)

TASK 21-31-34-400-001-A
Installation of the Cabin Pressure Controller (CPC)

ZONE: 121
ZONE: 122
FIN: 11HL
FIN: 12HL

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	ACCESS PLATFORM 1M(3 FT)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
121	AVIONICS COMPARTMENT
122	AVIONICS COMPARTMENT
811

C. Referenced Information

REFERENCE	DESIGNATION
TASK 21-31-00-710-002-A	Operational Test of the Pressure Control and Monitoring
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
TASK 24-42-00-862-001-A	De-energize the Ground Service Network Supplied from the External Power
Cabin Pressure Controller ** ON A/C NOT FOR ALL
Cabin Pressure Controller ** ON A/C NOT FOR ALL
Cabin Pressure Controller ** ON A/C NOT FOR ALL

3. Job Set-up
Subtask 21-31-34-860-050-A

A. Aircraft Maintenance Configuration
(1) Make sure that the ground service network is energized
(Ref. AMM TASK 24-42-00-861-001).

Subtask 21-31-34-865-052-A

B. Make sure that this(these) circuit breaker(s) is(are) open, safetied and tagged:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 11HL (PRESS CONT 1)
49VU	AIR COND/CAB/PRESS/CTL1	1HL	D09
122VU	AIR COND/CAB PRESS/CTL/MAN	3HL	Y23
FOR FIN: 12HL (PRESS CONT 2)
122VU	AIR COND/CAB PRESS/CTL/MAN	3HL	Y23
122VU	AIR COND/CAB PRESS/CTL/2	2HL	Y22

Subtask 21-31-34-010-052-A

C. Get Access
(1) Make sure that the ACCESS PLATFORM 1M(3 FT) is in position at access door 811.
(2) Make sure that access door 811 is open.

4. Procedure
Subtask 21-31-34-420-050-A ** ON A/C NOT FOR ALL

A. Installation of the Cabin Pressure Controller
(1) Clean the component interfaces and the adjacent area.
(2) Do an inspection of the component interfaces and the adjacent area.
(3) Remove the CAP-BLANKING from each electrical connector and receptacle.
(4) Make sure that all the electrical connections are clean and in the correct condition.
(5) Install the cabin pressure controller (1) on its rack (3).
(6) Push the cabin pressure controller (1) on its rack (3) to connect the electrical connector (2).
(7) Engage the nut (4) on the lug (5) and tighten.

CAUTION: MAKE SURE THAT THE PROTECTIVE CAP IS REMOVED FROM THE PRESSURE PORT OF THE CABIN PRESSURE CONTROLLER. IF NOT, THE PROTECTIVE CAP CAN CAUSE INCORRECT OPERATION OF THE CABIN PRESSURE CONTROL SYSTEM.

(8) Remove the protective cap (6) from the pressure port of the controller (1).

Subtask 21-31-34-420-050-B ** ON A/C NOT FOR ALL

(8) Removal of the protective caps (for controller with P/N type 20791-0XXX).

NOTE: There are no protective caps on controller with P/N type 20791-1XXX.

(a) Remove the protective caps (6) from the pressure ports of the controller (1).

Subtask 21-31-34-420-050-E ** ON A/C NOT FOR ALL

A. Installation of the CPC
(1) Clean the component interfaces and the adjacent area.
(2) Do an inspection of the component interfaces and the adjacent area.
(3) Remove the CAP-BLANKING from each electrical connector and receptacle.
(4) Make sure that all the electrical connections are clean and in the correct condition.
(5) Carefully put the CPC (1) in position on the rack (3).
(6) Push the CPC (1) to connect it to the electrical connector port (2).
(7) Tighten the nut (4) to the lug (5) of the CPC (1).
(8) Removal of the protective caps:

(a) Remove the protective caps (6) from the pressure port of the CPC (1).

Subtask 21-31-34-865-054-A

B. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 11HL (PRESS CONT 1)
49VU	AIR COND/CAB/PRESS/CTL1	1HL	D09
122VU	AIR COND/CAB PRESS/CTL/MAN	3HL	Y23
FOR FIN: 12HL (PRESS CONT 2)
122VU	AIR COND/CAB PRESS/CTL/MAN	3HL	Y23
122VU	AIR COND/CAB PRESS/CTL/2	2HL	Y22

Subtask 21-31-34-710-050-A

C. Do an operational test of the pressure control and monitoring (Ref. AMM TASK 21-31-00-710-002).

NOTE: Do this test for the CPC1 and CPC2. Make sure that the TEST OK indication or a fault indication comes into view on the MCDU. If the test is stopped, start the test again until the TEST OK indication or a fault indication comes into view on the MCDU.

5. Close-up
Subtask 21-31-34-410-050-A

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Close access door 811.
(3) Remove the access platform(s).

Subtask 21-31-34-862-050-A

B. De-energize the ground service network
(Ref. AMM TASK 24-42-00-862-001).

[Rev.10 from 2021] 2026.04.01 04:39:30 UTC