Removal of the Safety Valve

TASK 21-31-52-000-001-A
Removal 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	AR	CAP - BLANKING
No specific	AR	PLUG - BLANKING
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
811

C. Referenced Information

REFERENCE	DESIGNATION
TASK 24-41-00-861-002-A	Energize the Aircraft Electrical Circuits from the External Power
TASK 24-41-00-861-002-A-01	Energize the Aircraft Electrical Circuits from the APU
TASK 24-41-00-861-002-A-02	Energize the Aircraft Electrical Circuits from Engine 1(2)
TASK 52-41-00-010-002-A	Open the Avionics Compartment Doors for Access
Safety Valves 6HL (7HL)

3. Job Set-up
Subtask 21-31-52-861-051-A

A. Energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-861-002).

Subtask 21-31-52-865-050-A

B. Open, safety and tag 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 21-31-52-010-051-A

C. Open the forward avionics access door 811 (Ref. AMM TASK 52-41-00-010-002)

Safety Valves 6HL (7HL)

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.

(1) Remove the food trolleys from the Aft galley.
(2) Remove the access panel (1).

4. Procedure
Subtask 21-31-52-020-053-A

A. Removal of the Safety Valve
(1) If installed remove the safety wire from the electrical connector (2).
(2) Disconnect the electrical connector (2).
(3) Put the CAP-BLANKING on each disconnected electrical connector and receptacle.
(4) Remove the nut (8), the washer (7), the screw (5) and disconnect the bonding strap (6).
(5) Disconnect the ambient-pressure sense line (4).
(6) Put the PLUG-BLANKING in each disconnected line end.
(7) Hold the safety valve (3) and remove the clamp (9).
(8) Remove the safety valve (3) and the O-ring (10).
(9) Put blanking caps on the open ends of the safety valve (3) and the mounting flange (11).

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