Intercell XFR Valves (Left And Right Forward) - Fail To Latch At Fuel Low Level

TASK 28-15-00-810-811-A
Intercell XFR Valves (Left And Right Forward) - Fail To Latch At Fuel Low Level

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

RELAY-L OR R FWD XFR VALVE OPEN LATCH (14QP)
aircraft wiring
the suppression diode across terminals X and Z of the RELAY 14QP
FQIC [3QT]

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
AMM 28-15-00-710-002	Operational Check of Individual Transfer Valves to Ensure Valve Shaft Rotates Valve to Open Position
ASM 281502
AMM 28-42-34-000-001	Removal of the Fuel Quantity-Indicating Computer (FQIC)
AMM 28-42-34-400-001	Installation of the Fuel Quantity-Indicating Computer (FQIC)

3. Fault Confirmation
Subtask 28-15-00-710-060-A ** ON A/C NOT FOR ALL

A. Do the Operational Test of the Intercell Transfer Valves AMM 28-15-00-710-002, (9 and 10QP ONLY).

NOTE: The intercell transfer valves (ICTVs) are motor driven and the power for these circuits is derived from the main power. The ICTVs are immobilized on battery power.

(1) Connect a MULTIMETER - STANDARD to the RELAY-L OR R FWD XFR VALVE OPEN LATCH (14QP) as follows:

the multimeter negative/low input to terminal Z
the multimeter positive/high input to terminal X.

(2) Disconnect the lead from terminal 3 of RELAY-L OR R FWD XFR VALVE OPEN LATCH (14QP).
(3) After approximately 5 seconds to allow the valves to move, check that:
(a) The L and R XFR Valves show open on the FUEL System SD Page.
(b) The multimeter reads 28VDC.
(4) Reconnect the lead disconnected in (2) above.
(5) Check that:
(a) The L and R XFR Valves remain at open on the FUEL System SD Page.
(b) The multimeter reads 28VDC.
(6) Open C/Bs (3QP), M22 and (4QP), M23 at 121VU
(7) Close C/Bs (3QP), M22 and (4QP), M23 at 121VU
(8) On the FUEL System SD Page check that the Left and Right Transfer Valves return to the closed position.

4. Fault Isolation
Subtask 28-15-00-810-060-B ** ON A/C NOT FOR ALL

A. If:
(1) The multimeter reads 28VDC during the period that the valves are open.
(2) The valves close when the lead is reconnected to terminal 3 in Para 3.A.(4).
(3) Check/replace the RELAY-L OR R FWD XFR VALVE OPEN LATCH (14QP) .
(4) Do the test given in Para 3.A.
(5) If the multimeter does not read 28VDC in Para 3.A.(3)(b) above do a wiring check ASM 281502 of the:

aircraft wiring between the terminal X, of the RELAY 14QP and the pin C, of the connector AA, at ACTUATOR 9QP
aircraft wiring between the terminal X, of the RELAY 14QP and the pin C, of the connector AA, at ACTUATOR 10QP
aircraft wiring between the terminal Z, of the RELAY 14QP and the pin 9E, connector AB, at FQIC 3QT
the suppression diode across terminals X and Z of the RELAY 14QP .

(6) Repair/replace all the unserviceable wiring, diodes, and connectors.
(7) Do the test given in Para 3.A.
(8) If the fault continues replace the FQIC [3QT] AMM 28-42-34-000-001 and AMM 28-42-34-400-001.
(9) Do the test given in Para 3.A.

[Rev.8 from Aug 2018] 2026.04.04 04:28:29 UTC