Depressurization of the Potable Water System

TASK 38-10-00-614-002-A
Depressurization of the Potable Water 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 2M (6 FT)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
171AL

C. Referenced Information

REFERENCE	DESIGNATION
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
TASK 24-42-00-862-001-A	De-energize the Ground Service Network Supplied from the External Power
Forward Attendant Panel 124RH ** ON A/C NOT FOR ALL
Flight Attendant Panel 120RH ** ON A/C NOT FOR ALL

3. Job Set-up
Subtask 38-10-00-861-053-A

A. Energize the ground service network
(Ref. AMM TASK 24-42-00-861-001).

Subtask 38-10-00-865-053-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
2000VU	WATER SYSTEM-QANT-IND	1MA	B01
** ON A/C NOT FOR ALL
2001VU	WATER SYS-QUANT-IND	1MA	B06

Subtask 38-10-00-210-054-A

C. Make sure that the APU BLEED switch on the AIR COND panel 30VU is set to OFF if the APU is running.

Subtask 38-10-00-010-055-A ** ON A/C NOT FOR ALL

D. Get Access
(1) Open the lavatory door.
(2) Put the ACCESS PLATFORM 2M (6 FT) in position at Zone 171.
(3) Open the access door 171AL.

Subtask 38-10-00-010-055-B ** ON A/C NOT FOR ALL

D. Get Access
(1) Open the Lavatory door.

4. Procedure
Subtask 38-10-00-614-054-A ** ON A/C NOT FOR ALL

A. Depressurization of the Potable Water System
(1) Turn and pull the fill and drain handle at service panel 2023VU from the NORMAL position to the FILL position.
(2) Operate the water faucet in the lavatories to let air into the system.
(3) Push and turn the fill and drain handle to the NORMAL position.

Subtask 38-10-00-614-054-B ** ON A/C NOT FOR ALL

A. Depressurization of the Potable Water System

Forward Attendant Panel 124RH ** ON A/C NOT FOR ALL

(1) Press the membrane switch 'WATER SYS DEPRESS' on the FAP 124RH until the light comes on.

NOTE: The light in the membrane switch comes on when the depressurization valve 4MD opens.

(2) Operate the water faucet in the lavatories to let air into the system.
(3) Reactivation of the potable Water System
(a) Press the membrane switch 'WATER SYS DEPRESS' on the FAP 124RH again.
(b) The light in the membrane switch 'WATER SYS DEPRESS' is off.

Subtask 38-10-00-614-054-C ** ON A/C NOT FOR ALL

A. Depressurization of the Potable Water System

Flight Attendant Panel 120RH ** ON A/C NOT FOR ALL

(1) Push the 'WATER DEPRESS' button on the FAP 120RH:

The green light in the button comes on.
The message 'VACUUM SYSTEM DISABLED - WATER DEPRESS ACTIVE' comes on.
On the aircraft symbol 'NO WATER PRESSURE' comes in view.

NOTE: The green light in the 'WATER DEPRESS' button comes on when the depressurization valve 4MD opens.

(2) Operate the water faucet in the lavatories to let air into the system.
(3) Reactivation of the Potable water System
(a) Push the 'WATER DEPRESS' button on the FAP 120RH again.
(b) The green light in the 'WATER DEPRESS' button is off.
(4) No more messages are shown on the FAP.

5. Close-up
Subtask 38-10-00-862-051-A

A. De-energize the ground service network
(Ref. AMM TASK 24-42-00-862-001).

Subtask 38-10-00-410-057-A ** ON A/C NOT FOR ALL

B. Close Access
(1) Close the lavatory door.
(2) Close the service door 171AL.
(3) Remove the access platform(s).

Subtask 38-10-00-410-057-B ** ON A/C NOT FOR ALL

B. Close Access
(1) Close the lavatory door.

[Rev.10 from 2021] 2026.04.01 04:23:10 UTC