Fuel - FQI overread discrepancies in the Fuel on Board (FOB) and Fuel Used (FU)

TASK 28-42-00-810-883-A
Fuel - FQI overread discrepancies in the Fuel on Board (FOB) and Fuel Used (FU)

WARNING: OBEY THE FUEL SAFETY PROCEDURES.

1. Possible Causes

Engine fuel-flow sensor/transmitters
FQIS
FQIC [3QT]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 12-11-28-650-003	Pressure Refuel with Automatic Control
AMM 12-11-28-650-004	Pressure Refuel with Manual Control
AMM 12-11-28-650-007	Use of Magnetic Level Indicators (MLI)
AMM 28-25-00-650-001	Pressure Defuel
AMM 28-25-00-650-003	To Drain Remaining Fuel from the Wing Tanks and the Center Tank
AMM 28-42-00-740-001	Status Report (BITE)
AMM 28-42-00-740-007	Interrogation of the (SMITHS INDUSTRIES) FQIS Trouble Shooting Data
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 28-42-00-710-126-A

A. Test:

There is no fault confirmation test available for the values of Fuel On Board (FOB) and Fuel Used (FU) as used in the FOB and FU calculations. The airline operations, and the flight crew during flight, know the typical fuel load required for specific flight legs. Thus all significant discrepancies must be investigated.
(1) Do the Para. Fault Isolation.

4. Fault Isolation
Subtask 28-42-00-810-141-A

A. Procedure:
(1) Get as much data (as possible) about the FOB/FU discrepancy and the subsequent steps of the unusual and/or emergency procedure used, from:

the aircraft technical log
the flight crew.

(2) Fuel Used (FU):

NOTE: The FU data is supplied from each engine's FADEC system. The source of the data is the Engine fuel-flow sensor/transmitters mounted on the engines.

(a) Examine the PFR/CFDS(ENG) for a related flow sensor problem or message:
1 If a flow sensor problem or message is shown:
a Refer to the Fault Symptoms, at the front of the TSM and/or chapter 73, for the related task number.
b Do the applicable trouble shooting procedure related to the observation or failure message.
2 If there is no fuel flow sensor problem or message shown, do the next step.
(3) Fuel On Board (FOB):

NOTE: The FOB value is supplied from the FQIS .

(a) If the Fuel quantity is displayed degraded or fault reported in the PFR do the steps that follow:
1 If a flow sensor problem or message is shown:
a Refer to the Fault Symptoms, at the front of the TSM and/or chapeter 28, for the related task number.
b Do the applicable trouble shooting procedure related to the observation or failure message.
2 If there is no fuel flow sensor problem or message shown, do the next step.
(b) If the fuel quantity is not shown degraded, do one of the two sub steps 1 or 2 that follow:
1 The Refuel/Defuel:
a Fully defuel the aircraft AMM 28-25-00-650-001 and AMM 28-25-00-650-003.
b Refuel the aircraft AMM 12-11-28-650-003 or AMM 12-11-28-650-004.
c Make a record of the fuel load put on the aircraft as shown by the tanker or fuel hydrant.
d Do step (4).
2 Manual Magnetic Indicators (MMIs):
a Use the MMI secondary direct-reading system to calculate the FOB when the aircraft is on the ground AMM 12-11-28-650-007.
b Do step (4).
(4) Compare the FOB values obtained from the FQIS and defuel/refuel, or MMIs. If significant discrepancy is confirmed:
(a) Do the FQIC BITE test AMM 28-42-00-740-001 and print the FQIS troubleshooting data AMM 28-42-00-740-007.
(b) Replace the FQIC [3QT] AMM 28-42-34-000-001 and AMM 28-42-34-400-001.
(c) Report the problem to AIRBUS.

[Rev.8 from Aug 2018] 2026.04.04 04:29:12 UTC