Reactivation of the AFT Cargo Compartment-Heating Trim-Air Valve

TASK 21-43-00-440-002-A
Reactivation of the AFT Cargo Compartment-Heating Trim-Air 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.

ZONE: 197
FIN: 12HC ** ON A/C NOT FOR ALL

1. Reason for the Job
MMEL 21-43-02B
AFT CARGO COMPARTMENT HEATING
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

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
197	REAR FAIRING
197BB
197KB

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 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 53-35-13-000-002-A	Removal of the Quick-Release Access Panels from the Belly Fairing Structure

3. Job Set-up
Subtask 21-43-00-861-055-A ** ON A/C NOT FOR ALL

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

Subtask 21-43-00-865-056-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

Subtask 21-43-00-941-058-A ** ON A/C NOT FOR ALL

C. Safety Precautions
(1) On the panel 30VU:
(a) 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 legends are on).

(b) Put a warning notice in position to tell persons not to operate these switches.
(2) On the HP ground connector put a warning notice in position to tell persons not to supply the ground air.

Subtask 21-43-00-010-058-A ** ON A/C NOT FOR ALL

D. Get Access
(1) Put the ACCESS PLATFORM 2M (6 FT) in position at the access panel 197BB.
(2) Remove the access panel 197BB (Ref. AMM TASK 53-35-13-000-002).

Subtask 21-43-00-010-058-C ** ON A/C NOT FOR ALL

D. Get Access
(1) Put the ACCESS PLATFORM 2M (6 FT) in position at the access panel 197KB.
(2) Remove the access panel 197KB (Ref. AMM TASK 53-35-13-000-002).

4. Procedure
Subtask 21-43-00-440-051-C ** ON A/C NOT FOR ALL

A. Reactivation of the Trim Air Valve

WARNING: DO NOT TOUCH THE COMPONENT UNTIL IT IS SUFFICIENTLY COOL TO PREVENT BURNS.

(1) Remove the quick-release pin (4) from the manual override lever (2).
(2) Install the quick-release pin (4) in the stowage hole in the body of the trim air valve.
(3) Turn the manual override lever (2) to open the trim air valve.
(4) Remove the temporary attachment and the blanking caps from the electrical connectors (1) and reconnect them.

5. Close-up
Subtask 21-43-00-410-057-A ** ON A/C NOT FOR ALL

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Install the access panel 197BB.
(3) Remove the access platform(s).
(4) Remove the WARNING NOTICE(S).

Subtask 21-43-00-410-057-C ** ON A/C NOT FOR ALL

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Install the access panel 197KB.
(3) Remove the access platform(s).
(4) Remove the WARNING NOTICE(S).

Subtask 21-43-00-862-061-A ** ON A/C NOT FOR ALL

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

[Rev.10 from 2021] 2026.04.02 06:11:18 UTC