Vacuum Toilet System does not Operate Correctly on ground

TASK 38-31-00-810-823-A
Vacuum Toilet System does not Operate Correctly on ground

1. Possible Causes

membrane switch, WTR SYSTEM DEPRE
GENERATOR,VACUUM [37MG]
RELAY [36MG]
limit switch 44MG
CHECK VALVE 3320MM

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 38-30-00-010-002	Removal of the Toilet Drain Lines
AMM 38-30-00-410-002	Installation of the Toilet Drain Lines
AMM 38-31-00-710-008	Operational Test of the Door Limit Switch
AMM 38-31-00-710-009	Operational Test of the Toilet Unit
AMM 38-31-00-740-001	BITE Test of the Vacuum Toilet System
AMM 38-31-00-790-002	Leak Test of the Vacuum Toilet System
AMM 38-31-00-820-001	Adjustment of the Contact Point of the Waste Service-Panel-Door Limit-Switch
ASM 383110
AMM 38-31-13-000-001	Removal of the Waste Service-Panel Door Limit-Switch
AMM 38-31-13-400-001	Installation of the Waste Service-Panel Door Limit-Switch
AMM 38-31-64-000-001	Removal of the Vacuum Generator
AMM 38-31-64-400-001	Installation of the Vacuum Generator
AMM 38-31-65-000-001	Removal of the Check Valve
AMM 38-31-65-400-001	Installation of the Check Valve
MCDU Display

3. Fault Confirmation
Subtask 38-31-00-710-114-A ** ON A/C NOT FOR ALL

A. Make sure that the light in the membrane switch, WTR SYSTEM DEPRE on the FAP is OFF.

Subtask 38-31-00-710-092-A ** ON A/C NOT FOR ALL

B. Fault Confirmation Test
(1) Make sure that the circuit breakers of the Vacuum toilet system are closed.
(2) Do an operational test of the vacuum toilet system AMM 38-31-00-710-009.

Subtask 38-31-00-740-055-A ** ON A/C NOT FOR ALL

C. Do the bite test AMM 38-31-00-740-001.

4. Fault Isolation
Subtask 38-31-00-810-104-A ** ON A/C NOT FOR ALL

A. If the FAP gives the maintenance message SYSTEM INOP:

Refer to the LAST LEG REPORT or PREVIOUS LEGS REPORT page of the bite test.
MCDU Display ** ON A/C NOT FOR ALL

(1) If there is NO FAULTS indication on the LAST LEG REPORT or PREVIOUS LEGS REPORT page:

Operate the flush switches to flush the toilets.

(2) If the toilets rinse but do not flush:

open and close the circuit breaker 33MG.

(3) If the fault continues:

replace the GENERATOR,VACUUM [37MG] , AMM 38-31-64-000-001 and AMM 38-31-64-400-001.

(4) If the fault continues:

replace the RELAY [36MG]
do a check and repair the aircraft wiring ASM 383110.

Subtask 38-31-00-810-105-A ** ON A/C NOT FOR ALL

B. If the vacuum toilet system does not flush on the ground:

do a check of the door limit switch 44MG AMM 38-31-00-710-008.
do a check of the switch adjustment and adjust as necessary AMM 38-31-00-820-001.

(1) If the fault continues:

replace the door limit switch 44MG , AMM 38-31-13-000-001 and AMM 38-31-13-400-001.

(2) If the fault continues:

do a check of the aircraft wiring and repair as necessary ASM 383110.

Subtask 38-31-00-810-106-A ** ON A/C NOT FOR ALL

C. If the vacuum generator operates, but there is not sufficient vacuum:

do a leak check of the vacuum toilet system AMM 38-31-00-790-002.
replace the O-rings and or the vacuum toilet line as necessary AMM 38-30-00-010-002 and AMM 38-30-00-410-002.

(1) If the fault continues:

replace the CHECK VALVE 3320MM , AMM 38-31-65-000-001 and AMM 38-31-65-400-001.

Subtask 38-31-00-710-098-A ** ON A/C NOT FOR ALL

D. Test
(1) Do the test given as in paragraph 3. A. to check the correct operation.
(2) After the subsequent flight, make sure that the fault does not continue.

[Rev.8 from Aug 2018] 2026.04.04 04:34:14 UTC