No Pressurization of the Potable Water in Flight

TASK 38-12-00-810-814-A
No Pressurization of the Potable Water in Flight

1. Possible Causes

VALVE-OVERFLOW [8MP]
Fill limit switch 5MP
control cable 3260MM
aircraft wiring
control cable 3261MM
control cable 3254MM
FILL/DRAIN VALVE [8MA]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 12-15-38-613-001	Fill the Potable Water Tank System (Aircraft Electrical Power Available)
AMM 38-10-00-614-001	Pressurization of the Potable Water System from a Ground Air Supply
ASM 381300
ASM 381400
AMM 38-14-43-000-001	Removal of the Motorized Fill/Overflow-Drain Valve
AMM 38-14-43-400-001	Installation of the Motorized Fill/Overflow-Drain Valve
AMM 38-14-44-000-001	Removal of the Overflow Valve
AMM 38-14-44-400-001	Installation of the Overflow Valve
AMM 38-14-47-000-001	Removal of the Control Cable
AMM 38-14-47-400-001	Installation of the Control Cable
AMM 38-14-48-000-001	Removal of the Control Cable
AMM 38-14-48-400-001	Installation of the Control Cable

3. Fault Confirmation
Subtask 38-12-00-710-076-A

A. Aircraft configuration
(1) Make sure that there is water in the potable water system, if necessary do the servicing AMM 12-15-38-613-001.
(2) Make sure that the potable water system is pressurized AMM 38-10-00-614-001.

4. Fault Isolation
Subtask 38-12-00-810-063-A ** ON A/C NOT FOR ALL

A. If you cannot pressurize the potable water system:

do a check and make sure that no air flows from the VALVE-OVERFLOW [8MP] .

(1) If the over-flow valve 8MP is not closed:

do a check and adjust the Fill limit switch 5MP as necessary.

(2) If the fault continues:

do a check and make sure that the over-flow valve 8MP control cable 3260MM moves freely. If not, replace the control cable AMM 38-14-48-000-001 and AMM 38-14-48-400-001.

(3) If the fault continues:

replace the VALVE-OVERFLOW [8MP] , AMM 38-14-44-000-001 and AMM 38-14-44-400-001.

(4) If the fault continues:

do a check and repair the aircraft wiring between the:
CB 1MP and the connector A/C VALVE-OVERFLOW [8MP] , ASM 381400.

(5) If the fault continues:

do a check and make sure that the drain valve 14MP control cable 3261MM moves freely. If not, replace the control cable AMM 38-14-48-000-001 and AMM 38-14-48-400-001.

(6) If the fault continues:

do a check and make sure that the fill and drain valve 16MA control cable 3254MM moves freely. If not, replace the control cable AMM 38-14-47-000-001 and AMM 38-14-47-400-001.

Subtask 38-12-00-810-063-B ** ON A/C NOT FOR ALL

A. If you cannot pressurize the potable water system:

do a check and make sure that no air flows from the FILL/DRAIN VALVE [8MA] .

(1) If the fill/drain and overflow valve 8MA is not closed:

do a check and adjust the control cable 3254MM as necessary.

(2) If the fault continues:

do a check and make sure that the fill/drain and overflow valve 8MA control cable 3254MM moves freely. If not, replace the control cable AMM 38-14-47-000-001 and AMM 38-14-47-400-001.

(3) If the fault continues:

replace the FILL/DRAIN VALVE [8MA] , AMM 38-14-43-000-001 and AMM 38-14-43-400-001.

(4) If the fault continues:

do a check and repair the aircraft wiring between the:
CB 1MA and the connector A/C FILL/DRAIN VALVE [8MA] , ASM 381300.

5. Close-up
Subtask 38-12-00-710-077-A

A. After the subsequent flight, make sure that the fault does not continue.

[Rev.8 from Aug 2018] 2026.04.04 04:34:12 UTC