Removal of the Fwd Cargo Compartment Isolation Valve

TASK 21-28-51-000-001-A
Removal of the Fwd Cargo Compartment Isolation 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.

CAUTION: BE VERY CAREFUL WHEN YOU DO WORK ON OR NEAR THE AIR-CONDITIONING DUCTS. THE DUCTS ARE MADE OF THIN MATERIAL AND YOU CAN EASILY BREAK THEM.

ZONE: 131
ZONE: 132
FIN: 4HN ** ON A/C NOT FOR ALL
FIN: 5HN ** ON A/C NOT FOR ALL

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 3M (10 FT)- ADJUSTABLE
No specific	AR	CAP - BLANKING
No specific	AR	PLUG - BLANKING
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	WARNING NOTICE(S)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
131	FORWARD CARGO COMPARTMENT
132	FORWARD CARGO COMPARTMENT
825
FOR [4HN] (ISOL VALVE FWD CARGO OUTLET)
132KW
FOR [5HN] (ISOL VALVE FWD CARGO INLET)
131QW

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 25-54-12-000-003-A	Removal of the Sidewall Panels in the Forward Cargo Compartment
TASK 52-30-00-860-001-A	Open the FWD or Aft Cargo-Compartment Door with the Yellow Electric Pump
Isolation Valve
Isolation Valve

3. Job Set-up
Subtask 21-28-51-861-051-A ** ON A/C NOT FOR ALL

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

Subtask 21-28-51-941-051-A ** ON A/C NOT FOR ALL

B. Safety Precautions
(1) In the cockpit, on the overhead panel, on the AIR COND section of panel 30VU:
(a) Make sure that:
1 The APU BLEED pushbutton switch is in the off position (the ON legend is off).
2 The ENG 1 BLEED and the ENG 2 BLEED pushbutton switches are in the off position (the OFF legends are on).
3 The PACK 1 and PACK 2 pushbutton switches are released (the OFF legends are on).
(b) Put a WARNING NOTICE(S) in position to tell persons not to operate these pushbutton switches.
(2) On the HP and the LP ground connectors:
(a) Put a WARNING NOTICE(S) in position to tell persons not to supply the ground air.

Subtask 21-28-51-865-053-A ** ON A/C NOT FOR ALL

C. Open, safety and tag this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
49VU	AIR COND/FWD CARGO/VENT/CTL & MONG	2HN	C08
122VU	FWD CARGO VENT AND HTG/FAN	1HN	T22

Subtask 21-28-51-941-050-A ** ON A/C NOT FOR ALL

D. Put the ACCESS PLATFORM 3M (10 FT)- ADJUSTABLE in position.

Subtask 21-28-51-010-050-B ** ON A/C NOT FOR ALL

E. Get Access
(1) Open forward cargo-compartment door 825 (Ref. AMM TASK 52-30-00-860-001).
(2) Remove the sidewall panels (Ref. AMM TASK 25-54-12-000-003):
(a) FOR [4HN] (ISOL VALVE FWD CARGO OUTLET)
132KW.
(b) FOR [5HN] (ISOL VALVE FWD CARGO INLET)
131QW.

4. Procedure
Subtask 21-28-51-020-050-A ** ON A/C NOT FOR ALL

A. Removal of the Valve
(1) Disconnect the bonding strip (3).
(2) Disconnect the electrical connector (5) from the valve (4).
(3) Put a CAP - BLANKING on the disconnected electrical connector (5).
(4) Remove the clamps (6) and (8).
(5) Move the sleeve (7).
(a) For FIN 5HN on the duct (9) to release the valve (4).
(b) For FIN 4HN on the fan (9) to release the valve (4).
(6) Remove the clamp (2) and remove the valve (4).
(7) Remove the sleeve (7).
(8) Put PLUG - BLANKING:
(a) For FIN 5HN on the disconnected duct (1) and (9) ends.
(b) For FIN 4HN on the disconnected duct (1) and on the fan (9).

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