Installation of the Safety Valve

TASK 21-31-52-400-001-A
Installation of the Safety Valve

WARNING: MAKE SURE THAT AIR IS NOT SUPPLIED TO THE AIR CONDITIONING SYSTEM FROM THE MAIN ENGINE, THE APU OR A GROUND SOURCE. HOT COMPRESSED AIR CAN CAUSE INJURY TO PERSONNEL.

NOTE: The procedure is the same for the safety valves 6HL (7HL).

FIN: 6HL
FIN: 7HL

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

REFERENCE	QTY	DESIGNATION
No specific	Torque wrench: range to between 0.57 and 0.51 m.daN (50.44 and 45.13 lbf.in )
No specific	Torque wrench: range to between 0.65 and 0.6 m.daN (57.52 and 53.10 lbf.in )

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
811

C. Expendable Parts

FIG.ITEM	DESIGNATION	IPC-CSN
10	PACKING-PREFORMED	AIPC 21-31-04-10-020
10	PACKING-PREFORMED	AIPC 21-31-84-03-130

D. Referenced Information

REFERENCE	DESIGNATION
TASK 20-28-00-912-802-A	Electrical Bonding - General Maintenance Procedure
TASK 21-31-00-710-006-A	Operational Test of Safety Valve Position Indication
TASK 24-41-00-862-002-A	De-energize the Aircraft Electrical Circuits Supplied from the External Power
TASK 24-41-00-862-002-A-01	De-energize the Aircraft Electrical Circuits Supplied from the APU
TASK 24-41-00-862-002-A-02	De-energize the Aircraft Electrical Circuits Supplied from the Engine 1(2)
TASK 52-41-00-010-002-A	Open the Avionics Compartment Doors for Access
TASK 52-41-00-410-002-A	Close the Avionics Compartment Doors after Access
Safety Valves 6HL (7HL)

3. Job Set-up
Subtask 21-31-52-860-050-A

A. Aircraft Maintenance Configuration

Safety Valves 6HL (7HL)

(1) Make sure that:
(a) The forward avionics-bay access-door 811 is open (Ref. AMM TASK 52-41-00-010-002).

WARNING: OPEN THE ACCESS DOOR AND MAKE SURE IT STAYS OPEN. ATTACH A WARNING NOTICE TO THE ACCESS DOOR TO TELL PERSONS NOT TO CLOSE IT. THIS IS TO PREVENT ACCIDENTAL PRESSURIZATION OF THE AIRCRAFT BY THE AIR CONDITIONING SYSTEM IF ALL THE OTHER CABIN OPENINGS ARE CLOSED. PRESSURIZATION OF THE AIRCRAFT CAN BE DANGEROUS. IT CAN CAUSE A DOOR TO OPEN WITH EXPLOSIVE FORCE WHICH CAN CAUSE INJURY AND/OR DAMAGE.

(b) The food trolleys are removed from the Aft galley.
(c) The panel (1) is removed.

Subtask 21-31-52-865-051-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	AIR COND/CAB/PRESS/CTL1	1HL	D09
122VU	AIR COND/CAB PRESS/CTL/2	2HL	Y22

4. Procedure
Subtask 21-31-52-420-050-A

A. Installation of the Safety Valve

WARNING: USE PROTECTIVE GOGGLES AND GLOVES WHEN YOU REMOVE OR INSTALL LOCKWIRE. EACH TIME YOU CUT LOCKWIRE, REMOVE AND DISCARD IT IMMEDIATELY. LOOSE LOCKWIRE CAN CUT YOU OR MAKE YOU BLIND, AND/OR CAN CAUSE DAMAGE.

(1) Remove the blanking plugs from the mounting flange (11) and the safety valve (3).
(2) Clean the component interfaces and the adjacent area.
(3) Make sure that the parts retained from the removed component are clean and in the correct condition.
(4) Make sure that the packing (10) is in a good condition. If necessary renew the AIPC 21-31-04-10-020 PACKING-PREFORMED (10) or AIPC 21-31-84-03-130 PACKING-PREFORMED (10).
(5) Put the packing (10) and the safety valve (3) in position on the mounting flange (11).
(6) Install the clamp (9).

NOTE: Look in the Aft direction and make sure that:

For the safety valve 6HL the locking device of the clamp (9) is in the 3 o'clock position.
For the safety valve 7HL the locking device of the clamp (9) is in the 9 o'clock position.

Do not fully tighten the clamp (9) at this time.

(7) Remove the blanking plugs and install the ambient-pressure sense line (4).
(8) Make sure that the safety valve (3) is in the correct position.

NOTE: The ambient-pressure sense line (4) must have a continuous downward slope.

(9) Make sure that the clamp (9) is in the correct position and TORQUE to between 0.57 and 0.51 m.daN (50.44 and 45.13 lbf.in )

.
(10) TORQUE the ambient-pressure sense line (4) connector to between 0.65 and 0.6 m.daN (57.52 and 53.10 lbf.in )

.
(11) Put the bonding strap (6) in position and install the screw (5), the washer (7) and the nut (8) (Ref. AMM TASK 20-28-00-912-802).
(12) Remove the blanking caps and connect the electrical connector (2).
(13) Safety the electrical connector (2) with safety wire.

NOTE: Safety wire is not necessary if self-locking connector is installed.

(14) Make sure that the work area is clean and clear of tools and other items.

Subtask 21-31-52-865-053-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
49VU	AIR COND/CAB/PRESS/CTL1	1HL	D09
122VU	AIR COND/CAB PRESS/CTL/2	2HL	Y22

Subtask 21-31-52-710-050-A

C. Do the operational test of the safety valve position indication (Ref. AMM TASK 21-31-00-710-006).

5. Close-up
Subtask 21-31-52-410-050-A

A. Close Access

Safety Valves 6HL (7HL)

(1) Make sure that the work area is clean and clear of tools and other items.
(2) Install the panel (1) and the food trolleys in the Aft galley.
(3) Remove the warning notice and close the forward avionics-bay access-door 811 (Ref. AMM TASK 52-41-00-410-002).

Subtask 21-31-52-862-051-A

B. De-energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-862-002).

[Rev.10 from 2021] 2026.04.02 06:11:16 UTC