Leak Check of the Air supply System

TASK 38-41-00-790-002-A
Leak Check of the Air supply System

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 3M (10 FT)- ADJUSTABLE
No specific	AR	GAGE 10 BAR (145 PSI) - PRESSURE
No specific	AR	GROUND AIR-SUPPLY UNIT(HIGH PRESSURE)
No specific	Torque wrench: range to between 2.2 and 1.8 m.daN (16.22 and 13.27 lbf.ft )

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
171AL
131NW, 131PW
162DW

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 25-54-12-000-001-A	Removal of the Forward Cargo-Compartment Partition
TASK 25-54-12-400-001-A	Installation of the Forward Cargo-Compartment Partition
TASK 25-55-12-000-001-A	Removal of the Aft Cargo-Compartment Partition at FR65
TASK 25-55-12-400-001-A	Installation of the Aft Cargo-Compartment Partition at FR65
TASK 38-41-00-710-001-A	Operational Test of the Air Supply System (with ground air supply)
TASK 52-30-00-860-001-A	Open the FWD or Aft Cargo-Compartment Door with the Yellow Electric Pump
TASK 52-30-00-860-002-A	Close the FWD or Aft Cargo-Compartment Door with the Yellow Electric Pump
TASK 52-30-00-860-003-A	Open the FWD or Aft Cargo-Compartment Door with the Hand Pump
TASK 52-30-00-860-004-A	Close the FWD or Aft Cargo-Compartment Door with the Hand Pump
Test Connection of the Air Supply System ** ON A/C NOT FOR ALL
Test Connection of the Air Supply System ** ON A/C NOT FOR ALL

3. Job Set-up
Subtask 38-41-00-861-054-A

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

Subtask 38-41-00-010-056-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the aft cargo-compartment door (Ref. AMM TASK 52-30-00-860-001) (Ref. AMM TASK 52-30-00-860-003).
(2) Put an ACCESS PLATFORM 3M (10 FT)- ADJUSTABLE in position below the aft cargo-compartment door.
(3) Set aft cargo-compartment light switch 8LU on service panel 2024VU to the ON position.
(4) Remove partition 162DW (Ref. AMM TASK 25-55-12-000-001).
(5) Open potable-water service panel 171AL.

Subtask 38-41-00-010-056-B ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the FWD cargo-compartment door (Ref. AMM TASK 52-30-00-860-001).
(2) Put the ACCESS PLATFORM 3M (10 FT)- ADJUSTABLE in position below the FWD cargo-compartment door.
(3) Set the FWD CARGO-COMPT LIGHT switch 6LU to the ON position.
(4) Remove the access panels 131NW 131PW (Ref. AMM TASK 25-54-12-000-001).
(5) Open the potable water-service panel 171AL.

Subtask 38-41-00-480-054-A

C. Installation of the Test Equipment

Test Connection of the Air Supply System ** ON A/C NOT FOR ALL

(1) Remove the cap from the test connection port and connect the GAGE 10 BAR (145 PSI) - PRESSURE to the

Test port installed on top of the potable water tank. If necessary, use a T-connection to connect it, or
Test port installed near the pressure reducing and relief valve 4200MM.

(2) Connect the GROUND AIR-SUPPLY UNIT(HIGH PRESSURE) to the ground air connection at potable-water service panel 171AL.

4. Procedure
Subtask 38-41-00-790-051-B ** ON A/C NOT FOR ALL

A. Leak Check of the Air Supply System
(1) Close the shutoff valves in the lavatories and galleys.
(2) Make sure that the depressurization system on the FAP is not ON.
(3) Pressurize the system to between 39 psi (2.6890 bar) and 41 psi (2.8269 bar).
(4) Make sure that the pressure indication on the manometer is stable between 22 psi (1.5168 bar) and 33 psi (2.2753 bar) (Ref. AMM TASK 38-41-00-710-001).
(5) Stop the pressure supply to the potable-water service panel.
(6) Make sure that the pressure indication at the manometer stays the same after 20 min.
(7) Increase the pressure at the potable-water service panel to 55 +0 psi or -3 psi (3.7921 +0.0000 bar or -0.2068 bar) and keep this pressure for 5 min.
(8) Do a check for leaks at the air lines from the potable water service panel to the potable water tank.

NOTE: Leakage at the adjuster of the pressure reducing and relief valve 4200MM is permitted.

(9) Stop the pressure supply to the potable-water service panel.
(10) Put the fill/drain handle to the FILL position for approximately 5 seconds to release the pressure from the system.
(11) Open the shutoff valves in the lavatories and galleys.

Subtask 38-41-00-790-051-C ** ON A/C NOT FOR ALL

A. Leak Check of the Air Supply System
(1) Close the shutoff valves in the lavatories and galleys.
(2) Pressurize the system to between 39 psi (2.6890 bar) and 41 psi (2.8269 bar).
(3) Make sure that the pressure indication on the manometer is stable between 25 psi (1.7237 bar) and 28 psi (1.9305 bar) (Ref. AMM TASK 38-41-00-710-001).
(4) Stop the pressure supply to the potable-water service panel.
(5) Make sure that the pressure indication at the manometer stays the same after 20 minutes.
(6) Increase the pressure at the potable-water service panel to 55 +0 psi or -3 psi (3.7921 +0.0000 bar or -0.2068 bar) and keep this pressure for 5 minutes.
(7) Do a check for leaks at the air lines from the potable-water service panel to the potable water tank.

NOTE: Leakage at the adjuster of the pressure reducing and relief valve 4200MM is permitted.

(8) Stop the pressure supply to the potable-water service panel.
(9) Put the fill/drain handle to the FILL position for approximately 5 seconds to release the pressure from the system.
(10) Open the shutoff valves in the lavatories and galleys.

5. Close-up
Subtask 38-41-00-080-053-A

A. Removal of the Test Equipment
(1) Remove the GROUND AIR-SUPPLY UNIT(HIGH PRESSURE) from the ground air connection at the potable-water service panel.
(2) Remove the GAGE 10 BAR (145 PSI) - PRESSURE from the test port of the potable-water air system.
(3) Install the cap.
(4) TORQUE the cap to between 2.2 and 1.8 m.daN (16.22 and 13.27 lbf.ft )

Subtask 38-41-00-410-057-A ** ON A/C NOT FOR ALL

B. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Install partition 162DW (Ref. AMM TASK 25-55-12-400-001).
(3) Set cargo-compartment light switch 8LU to the OFF position.
(4) Remove the access platform(s).
(5) Close the aft cargo-compartment door (Ref. AMM TASK 52-30-00-860-002) (Ref. AMM TASK 52-30-00-860-004).
(6) Close potable-water service panel 171AL.

Subtask 38-41-00-410-057-B ** ON A/C NOT FOR ALL

B. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Set the light switch 6LU to the OFF position.
(3) Close the access panels 131NW and 131PW (Ref. AMM TASK 25-54-12-400-001).
(4) Remove the access platform(s).
(5) Close the FWD cargo-compartment door (Ref. AMM TASK 52-30-00-860-002).
(6) Close the potable water-service panel 171AL.

Subtask 38-41-00-942-055-A

C. Remove the ground support and maintenance equipment, the special and standard tools and all other items.

Subtask 38-41-00-862-055-A

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

[Rev.10 from 2021] 2026.04.02 06:26:00 UTC