Functional Test of the Pressure Switch

TASK 38-42-00-720-001-A
Functional Test of the Pressure Switch

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	1	GAGE 5 BAR (75 PSI) - PRESSURE
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
162DW

C. Referenced Information

REFERENCE	DESIGNATION
TASK 12-15-38-613-001-A	Fill the Potable Water Tank System (Aircraft Electrical Power Available)
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 25-55-12-000-001-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 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

3. Job Set-up
Subtask 38-42-00-861-056-A ** ON A/C NOT FOR ALL

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

Subtask 38-42-00-010-056-C ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the aft cargo-compartment door (Ref. AMM TASK 52-30-00-860-001).
(2) Put an ACCESS PLATFORM 2M (6 FT) at the aft cargo-compartment door.
(3) Remove partition 162DW (Ref. AMM TASK 25-55-12-000-001).

Subtask 38-42-00-865-060-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
2001VU	WATER SYS-AIR-COMPRESSOR	19MD	F01

Subtask 38-42-00-480-051-A ** ON A/C NOT FOR ALL

D. Connect a GAGE 5 BAR (75 PSI) - PRESSURE:

To the test port installed on top of the potable water tank. Use a T-connection to connect it, or
To the test port installed at the pressure reducing and relief valve.

Subtask 38-42-00-865-061-A ** ON A/C NOT FOR ALL

E. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
2001VU	WATER SYS-AIR-COMPRESSOR	19MD	F01

Subtask 38-42-00-613-053-A ** ON A/C NOT FOR ALL

F. Fill the potable water tank (Ref. AMM TASK 12-15-38-613-001).

4. Procedure
Subtask 38-42-00-720-050-B ** ON A/C NOT FOR ALL

A. Do this test.

NOTE: Before you start the test, make sure that there are no leaks in the compressor.

ACTION	RESULT
1.In an aft lavatory: Turn the water faucet to the open to release the pressure in the potable water system. Close the water faucet again when the pressure is released.	In the lavatory: Water flows into the wash basin. The flow rate of the water decreases.
2.At service panel 2023VU: Push and hold limit switch 5MA until the manometer shows 25 psi (1.7237 bar).	In the air boost system: Pressure switch 10MD closes. Relay 9MD is energized. Air compressor 8MD starts to operate. The potable water system starts to pressurize.
	In the lavatory: The water flow increases.
3.At service panel 2023VU: Continue to hold limit switch 5MA pushed in.	In the air boost system: When the manometer shows 28 psi (1.9305 bar) Pressure switch 10MD opens. Relay 9MD is de-energized. The operation of air compressor 8MD stops.
4.Do step 1 to 3 again and make sure that the air compressor: Starts at 25 psi (1.7237 bar) Stops at 28 psi (1.9305 bar).
5.At service panel 2023VU: Release limit switch 5MA.	In the air boost system: Relay 9MD is de-energized. Air compressor 8MD does not operate.

5. Close-up
Subtask 38-42-00-080-051-A ** ON A/C NOT FOR ALL

A. Remove the pressure gauge and install the blanking plug on the test connection.

Subtask 38-42-00-613-054-A ** ON A/C NOT FOR ALL

B. If necessary fill the potable water tank (Ref. AMM TASK 12-15-38-613-001).

Subtask 38-42-00-410-056-C ** ON A/C NOT FOR ALL

C. 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) Close the aft cargo-compartment door (Ref. AMM TASK 52-30-00-860-002).
(4) Remove the access platform(s).

Subtask 38-42-00-862-056-A ** ON A/C NOT FOR ALL

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

[Rev.10 from 2021] 2026.04.02 06:26:01 UTC