Fuel Pumps - Left Wing Tank Fuel Pump No. 1 System Failure (Standby Supply)

TASK 28-21-00-810-805-A
Fuel Pumps - Left Wing Tank Fuel Pump No. 1 System Failure (Standby Supply)

WARNING: OBEY THE FUEL SAFETY PROCEDURES.

WARNING: WHEN YOU DO WORK ON THE FUEL SYSTEM WIRING, YOU MUST USE TEST EQUIPMENT THAT IS APPROVED (REFER TO INTERNATIONAL OR NATIONAL SPECIFICATIONS FOR INTRINSICALLY SAFE TEST EQUIPMENT: EN50020, UL913 OR EQUIVALENT). TEST EQUIPMENT THAT IS NOT APPROVED CAN CAUSE FIRE OR AN EXPLOSION.

1. Possible Causes

C/B-L WING TK/PUMP 1/STBY SPLY [11QA]
CT-AC, 1 [42XU3]
CNTOR-L WING TK STBY SPLY, PUMP 1 [53QA]
aircraft wiring (three phase electrical standby supply)

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	MULTIMETER - STANDARD

B. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 28-21-00-810-801-A	Fuel Pumps - Left Wing Tank Fuel Pump No. 1 (Outer) 21QA System Malfunction
TSM TASK 28-21-00-810-807-A	Fuel Pumps - Left Wing Tank Fuel Pump No. 1 Contactor Control Failure (Normal Supply)
AMM 24-22-00-710-001	Operational Test of the Generator Line Contactor (GLC-1) Opening in the Smoke Procedure
ASM 242202
AMM 24-22-17-000-001	Removal of the AC Current Transformers
AMM 24-22-17-400-001	Installation of the AC Current Transformers
ASM 282101

3. Fault Confirmation
Subtask 28-21-00-710-054-A

A. Test
(1) Do the Operational Test of the Generator Line Contactor (GLC-1) Opening in the Smoke Procedure AMM 24-22-00-710-001.
(2) If a low fuel pressure indiction is shown when the left wing tank fuel pump No. 1 is supplied from:
(a) The normal supply (AC BUS 1 and through the contactor-17QA), do (Ref. TSM TASK 28-21-00-810-801) and (Ref. TSM TASK 28-21-00-810-807).
(b) The standby supply (direct from the Generator No. 1 and through the contactor-53QA), do Para. 4.A.

4. Fault Isolation
Subtask 28-21-00-810-054-B

A. Procedure
(1) Do a check of ASM 282101 and replace, if necessary:

the C/B- C/B-L WING TK/PUMP 1/STBY SPLY [11QA]
the CT-AC, 1 [42XU3] AMM 24-22-17-000-001 and AMM 24-22-17-400-001
the CNTOR-L WING TK STBY SPLY, PUMP 1 [53QA] .

(2) Do a check, with a MULTIMETER - STANDARD, of the aircraft wiring (three phase electrical standby supply) ASM 242202 and ASM 282101 between:

the contactor GLC-1 (9XU1) (Gen 1 connected terminals D, E and F) and the C/B-L WING TK/PUMP 1/STBY SPLY (11QA)

NOTE: Each phase of the wiring between these two units goes through a different toroidal transformer of the CT-AC, 1 (42XU3). There is no direct electrical connection.

the C/B-L WING TK/PUMP 1/STBY SPLY (11QA) and the CNTOR-L WING TK STBY SPLY, PUMP 1 (53QA)
CNTOR-L WING TK STBY SPLY, PUMP 1 (53QA) and the PUMP-FUEL No. 1, L WING TK free connector 21QA-A.

(3) Repair the unserviceable wiring and connectors.
(4) Do the test given in Para. 3.A.

[Rev.8 from Aug 2018] 2026.04.04 04:28:34 UTC