Hot-Air Leak-Check in the Air Conditioning Bay

TASK 21-52-00-200-010-A
Hot-Air Leak-Check in the Air Conditioning Bay

FIN: 10HM
FIN: 11HM

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
191BB, 191KB, 192KB

B. Referenced Information

REFERENCE	DESIGNATION
TASK 12-33-21-618-001-A-01	Pre-conditioning through the HP Ground Connection
TASK 12-33-21-618-001-A-02	Pre-conditioning with the APU
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
TASK 53-35-13-400-002-A	Installation of the Quick-Release Access Panels on the Belly Fairing Structure
Air Conditioning Bay - Component Location ** ON A/C NOT FOR ALL
Air Conditioning Bay - Component Location ** ON A/C NOT FOR ALL

3. Job Set-up
Subtask 21-52-00-861-060-A

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

Subtask 21-52-00-865-071-A

B. Make sure that this(these) circuit breaker(s) is(are) closed:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
49VU	AIR COND/FLOW/CTL &/IND1	1HB	D07
49VU	AIR COND/FLOW/CTL &/IND1	1HB	D07
** ON A/C NOT FOR ALL
49VU	AIR COND/TEMP CTL/SYS 1 CHAN B/28VDC	52HH	D08
** ON A/C NOT FOR ALL
122VU	AIR COND/FLOW/MIXER/FLAP	3HB	V22
122VU	AIR COND/FLOW/MIXER/FLAP	3HB	V22
122VU	AIR COND/FLOW/CTL AND IND/2	2HB	V21
122VU	AIR COND/FLOW/CTL AND IND/2	2HB	V21
122VU	AIR COND/ZONE TEMP CTL/28VDC/SYS2	4HK	V20
122VU	AIR COND/ZONE TEMP CTL/28VDC/SYS2	4HK	V20
122VU	AIR COND/ZONE TEMP CTL/28VDC/SYS1	3HK	V19
122VU	AIR COND/ZONE TEMP CTL/28VDC/SYS1	3HK	V19
122VU	AIR COND/ZONE TEMP CTL/115VAC/SYS2	2HK	V18
122VU	AIR COND/ZONE TEMP CTL/115VAC/SYS2	2HK	V18
122VU	AIR COND/ZONE TEMP CTL/115VAC/SYS1	1HK	V17
122VU	AIR COND/ZONE TEMP CTL/115VAC/SYS1	1HK	V17
122VU	AIR COND/PACK TEMP/CTL SYS1/2/115VAC	21HH	W22
122VU	AIR COND/PACK TEMP/CTL SYS1/2/28VDC	23HH	W21
122VU	AIR COND/PACK TEMP/CTL SYS1/1/115VAC	1HH	X22
122VU	AIR COND/PACK TEMP/CTL SYS1/1/28VDC	3HH	X21
122VU	AIR COND/PACK TEMP CTL SYS2/2/28VDC	24HH	Y21
122VU	AIR COND/PACK TEMP CTL SYS2/2/115VAC	22HH	Y20
122VU	AIR COND/PACK TEMP CTL SYS2/1/28VDC	4HH	Y19
122VU	AIR COND/PACK TEMP CTL SYS2/1/115VAC	2HH	Y18
** ON A/C NOT FOR ALL
122VU	AIR COND/TEMP CTL SYS 2/CHAN A/115VAC	53HH	W22
122VU	AIR COND/TEMP CTL SYS 2/CHAN A/28VDC	55HH	W21
122VU	AIR COND/TEMP CTL SYS 1/CHAN A/115VAC	49HH	X22
122VU	AIR COND/TEMP CTL SYS 1/CHAN A/28VDC	51HH	X21
122VU	AIR COND/TEMP CTL SYS 2/CHAN B/28VDC	56HH	Y21
122VU	AIR COND/TEMP CTL SYS 2/CHAN B/115VAC	54HH	Y20
122VU	AIR COND/TEMP CTL SYS 1/CHAN B/115VAC	50HH	Y18

Subtask 21-52-00-010-068-A

C. Get Access
(1) Remove the access panel(s) (Ref. AMM TASK 53-35-13-000-002).

4. Procedure
Subtask 21-52-00-790-051-B ** ON A/C NOT FOR ALL

WARNING: PUT ON PROTECTIVE GOGGLES AND THERMAL GLOVES WHEN YOU GO NEAR AN AIR-CONDITIONING PACK WHEN IT OPERATES. THERE CAN BE LEAKAGE OF HOT AIR, WHICH CAN CAUSE INJURIES.

A. Hot-Air Leak-Check

Air Conditioning Bay - Component Location ** ON A/C NOT FOR ALL

(1) Do the pre-conditioning through the HP ground connector (Ref. AMM TASK 12-33-21-618-001) or with the APU (Ref. AMM TASK 12-33-21-618-001).
(2) Do the Check for Hot-Air Leaks
Do this check on all the hot components which are located in the air conditioning bay:

The APU bleed-air duct with its sleeves and clamps (1).
The crossfeed duct with its sleeves and clamps (2).
The ozone filter (7).
The flow control valve (3).
The duct between the flow control valve and the primary heat exchanger (4).
The duct between the primaray heat exchanger and the compressor of the air cycle machine (5).
The compressor of the air cycle machine and the main heat exchanger (6).

NOTE: There is a higher risk of leaks at the clamps and seals at the duct connections than at the ducts itselves.

(3) Repair all leaks.
(4) Stop the pre-conditioning (Ref. AMM TASK 12-33-21-618-001) or (Ref. AMM TASK 12-33-21-618-001).

Subtask 21-52-00-790-051-D ** ON A/C NOT FOR ALL

A. Hot-Air Leak-Check

Air Conditioning Bay - Component Location ** ON A/C NOT FOR ALL

WARNING: PUT ON PROTECTIVE GOGGLES AND THERMAL GLOVES WHEN YOU GO NEAR AN AIR-CONDITIONING PACK WHEN IT OPERATES. THERE CAN BE LEAKAGE OF HOT AIR, WHICH CAN CAUSE INJURIES.

(1) Do the pre-conditioning through the HP ground connector (Ref. AMM TASK 12-33-21-618-001) or with the APU (Ref. AMM TASK 12-33-21-618-001).
(2) Do a Check for Hot-Air Leaks
Do this check on all the hot components which are in the air conditioning bay:

The APU bleed-air duct with its sleeves and clamps (1).
The crossfeed duct with its sleeves and clamps (2).
The flow control unit (3).
The ozone filter (7).
The duct between the flow control unit and the primary heat exchanger (4).
The duct between the primary heat exchanger and the compressor of the air cycle machine (5).
The compressor of the air cycle machine and the main heat exchanger (6).

NOTE: There is a higher risk of leaks at the clamps and seals at the duct connections than at the ducts themselves.

(3) Repair all leaks.
(4) Stop the pre-conditioning (Ref. AMM TASK 12-33-21-618-001) or (Ref. AMM TASK 12-33-21-618-001).

5. Close-up
Subtask 21-52-00-410-067-A

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Install the access panel(s) (Ref. AMM TASK 53-35-13-400-002)

Subtask 21-52-00-862-059-A

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

[Rev.10 from 2021] 2026.04.02 06:11:25 UTC