Adjacent Wing Tank Fuel Pump, Pressure-Switch Isolating Check-Valve Failure

TASK 28-21-00-810-842-A
Adjacent Wing Tank Fuel Pump, Pressure-Switch Isolating Check-Valve Failure

WARNING: OBEY THE FUEL SAFETY PROCEDURES.

1. Possible Causes

CHECK VALVE-FUEL PUMP,L WING TK OUTR [33QM]
CHECK VALVE-FUEL PUMP, L WING TK INR [34QM]
CHECK VALVE-FUEL PUMP, R WING TK INR [35QM]
CHECK VALVE-FUEL PUMP, R WING TK OUTR [36QM]
CHECK VALVE [224QM]
CHECK VALVE [222QM]
CHECK VALVE [223QM]
CHECK VALVE [225QM]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 28-16-42-000-002	Removal of the Check Valve
AMM 28-16-42-400-002	Installation of the Check Valves
AMM 28-21-00-710-001	Operational Test of the Wing-Tank Fuel Control
AMM 28-21-00-710-002	Operational Check of Wing Tank Pump Pressure Sense Line Check Valves
AMM 28-21-43-000-001	Removal of the Fuel-Pump Check-Valve
AMM 28-21-43-400-001	Installation of the Fuel-Pump Check-Valve

3. Fault Confirmation
Subtask 28-21-00-710-088-A

A. Do the Operational Test of the Wing-Tank Fuel Control for the related Wing Tank Fuel-Pump AMM 28-21-00-710-001.

NOTE: The above test is called for as it is important to make sure that the related fuel-pump pressure switch and the low pressure indications are correct before you start more steps.

(1) If a failure is detected during the above test:

do the applicable troubleshooting procedure.

(2) Do the Operational Test of the Wing Tank Pump Pressure Sense Line Check Valves AMM 28-21-00-710-002.

NOTE: It is important to carefully examine the related fuel-pump push button switch (P/BSW) when the fuel-pumps are switched on. This is to make sure that the FAULT indication shows momentarily (if the check valves are operating correctly).

4. Fault Isolation
Subtask 28-21-00-810-088-A ** ON A/C NOT FOR ALL

A. If during the test in Para. 3.A.(2):
(1) The FAULT indication of the P/BSW-FUEL/L TK PUMPS/1 (13QA) fails to momentarily show:

replace the CHECK VALVE-FUEL PUMP,L WING TK OUTR [33QM] AMM 28-21-43-000-001 and AMM 28-21-43-400-001.

(2) The FAULT indication of the P/BSW-FUEL/L TK PUMPS/2 (15QA) fails to momentarily show:

replace the CHECK VALVE-FUEL PUMP, L WING TK INR [34QM] AMM 28-21-43-000-001 and AMM 28-21-43-400-001.

(3) The FAULT indication of the P/BSW-FUEL/R TK PUMPS/1 (14QA) fails to momentarily show:

replace the CHECK VALVE-FUEL PUMP, R WING TK INR [35QM] AMM 28-21-43-000-001 and AMM 28-21-43-400-001.

(4) The FAULT indication of the P/BSW-FUEL/R TK PUMPS/2 (16QA) fails to momentarily show:

replace the CHECK VALVE-FUEL PUMP, R WING TK OUTR [36QM] AMM 28-21-43-000-001 and AMM 28-21-43-400-001.

(5) Do the test given in Para. 3.A.

Subtask 28-21-00-810-088-B ** ON A/C NOT FOR ALL

A. If during the test in Para. 3.A.(2):
(1) The FAULT indication of the P/BSW-FUEL/L TK PUMPS/1 (13QA) fails to momentarily show:

replace the CHECK VALVE [224QM] AMM 28-16-42-000-002 and AMM 28-16-42-400-002.

(2) The FAULT indication of the P/BSW-FUEL/L TK PUMPS/2 (15QA) fails to momentarily show:

replace the CHECK VALVE [222QM] AMM 28-16-42-000-002 and AMM 28-16-42-400-002.

(3) The FAULT indication of the P/BSW-FUEL/R TK PUMPS/1 (14QA) fails to momentarily show:

replace the CHECK VALVE [223QM] AMM 28-16-42-000-002 and AMM 28-16-42-400-002.

(4) The FAULT indication of the P/BSW-FUEL/R TK PUMPS/2 (16QA) fails to momentarily show:

replace the CHECK VALVE [225QM] AMM 28-16-42-000-002 and AMM 28-16-42-400-002.

(5) Do the test given in Para. 3.A.

[Rev.8 from Aug 2018] 2026.04.04 04:28:38 UTC