Removal of the AFT Cargo-Compartment Ventilation Isolation-Valves

TASK 21-28-52-000-001-A
Removal of the AFT Cargo-Compartment Ventilation Isolation-Valves

FIN: 33HN ** ON A/C NOT FOR ALL
FIN: 34HN ** 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	1	ACCESS PLATFORM 2M (6 FT)
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
FOR [33HN] (ISOL VALVE AFT CARGO OUTLET)
No specific	AR	CAP - BLANKING
FOR [34HN] (ISOL VALVE AFT CARGO INLET)
No specific	AR	CAP - BLANKING

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
826
FOR [33HN] (ISOL VALVE AFT CARGO OUTLET)
162DW
FOR [34HN] (ISOL VALVE AFT CARGO INLET)
151EW
151VW

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 52-30-00-860-001-A	Open the FWD or Aft Cargo-Compartment Door with the Yellow Electric Pump
AFT Cargo Isolation Valves ** ON A/C NOT FOR ALL
AFT Cargo Isolation Valves ** ON A/C NOT FOR ALL
FOR [33HN] (ISOL VALVE AFT CARGO OUTLET)
TASK 25-55-12-000-001-A	Removal of the Aft Cargo-Compartment Partition at FR65
FOR [34HN] (ISOL VALVE AFT CARGO INLET)
TASK 25-55-11-000-003-A	Removal of the Sidewall Panels in the Aft Cargo Compartment - FR47/FR59

3. Job Set-up
Subtask 21-28-52-861-051-A ** ON A/C NOT FOR ALL

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

Subtask 21-28-52-865-050-A ** ON A/C NOT FOR ALL

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
49VU	AIR COND/AFT CARGO/VENT/CTL & MONG	31HN	C07
** ON A/C NOT FOR ALL
49VU	AIR COND/AFT CARGO/VENT & HTG/CTL & MONG	31HN	C07
** ON A/C NOT FOR ALL
122VU	AIR COND/AFT CARGO VENT/FAN	30HN	S22

Subtask 21-28-52-865-064-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/AFT CARGO/VENT/CTL & MONG	31HN	C07
** ON A/C NOT FOR ALL
49VU	AIR COND/AFT CARGO/VENT & HTG/CTL & MONG	31HN	C07

Subtask 21-28-52-941-052-A ** ON A/C NOT FOR ALL

D. Safety Precautions
(1) FOR [34HN] (ISOL VALVE AFT CARGO INLET)
(a) On the panel 30VU:
1 Make sure that:

the APU BLEED pushbutton switch is in the off position (the ON legend is off) and
the ENG 1 BLEED and the ENG 2 BLEED pushbutton switches are in the off position (the OFF legend is on).

2 Put a warning notice in position to tell persons not to operate these pushbutton switches.
(b) On the HP and the LP ground connectors:
1 Put a warning notice in position to tell persons not to supply the ground air.

Subtask 21-28-52-010-050-A ** ON A/C NOT FOR ALL

E. Get Access
(1) Open the AFT cargo-compartment door 826 (Ref. AMM TASK 52-30-00-860-001).
(2) Put the ACCESS PLATFORM 2M (6 FT) in position at the AFT cargo-compartment door 826.
(3) Remove the access panel:
(a) FOR [33HN] (ISOL VALVE AFT CARGO OUTLET)
162DW (Ref. AMM TASK 25-55-12-000-001).
(b) FOR [34HN] (ISOL VALVE AFT CARGO INLET)
151EW (Ref. AMM TASK 25-55-11-000-003).

Subtask 21-28-52-010-050-C ** ON A/C NOT FOR ALL

4. Procedure
Subtask 21-28-52-020-050-A ** ON A/C NOT FOR ALL

A. Removal of the Isolation Valve
(1) FOR [34HN] (ISOL VALVE AFT CARGO INLET)
(a) Disconnect the electrical connector (10).
(b) Put the CAP-BLANKING on each disconnected electrical connector and receptacle.
(c) Remove the nut (5), the washer (6), the screw (7), the washer (8) and disconnectthe bonding strap (9).
(d) Remove the clamp (12) and disconnect the sleeve (1).
(e) Hold the isolation valve (11) and remove the clamp (3).
(f) Remove the isolation valve (11).
(g) Put blanking plugs on the open ends of the isolation valve (11), the sleeve (1) and the duct flange (2).
(2) FOR [33HN] (ISOL VALVE AFT CARGO OUTLET)
(a) Disconnect the electrical connector (18).
(b) Put the CAP-BLANKING on each disconnected electrical connector and receptacle.
(c) Remove the nut (23), the washer (22), the screw (19), the washer (20) and disconnect the bonding strap (21).
(d) Remove the clamp (16) and disconnect the sleeve (15).
(e) Remove the clamp (25).
(f) Hold the isolation valve (24) and remove the clamp (17).
(g) Remove the isolation valve (24).
(h) Put blanking plugs on the open ends of the isolation valve (24), the sleeve (15) and the duct flange (13).

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