FQIS and ECAM FQIs Fluctuate When ADIRS is set to off

TASK 28-42-00-810-874-A
FQIS and ECAM FQIs Fluctuate When ADIRS is set to off

WARNING: OBEY THE FUEL SAFETY PROCEDURES.

1. Possible Causes

FQIC [3QT]
you are not sure of the quality of the aircraft fuel
water in the tanks
fuel-tank microbiological contamination
FQIS fuel tank harness
fused connector/adaptor
fuel probe

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 28-42-00-810-801-A	Fuel Quantity Indication Computer (FQIC) 3QT
AMM 12-11-28-650-003	Pressure Refuel with Automatic Control
AMM 12-11-28-650-004	Pressure Refuel with Manual Control
ESPM 2053210
AMM 24-41-00-861-002	Energize the Aircraft Electrical Circuits from the External Power
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 28-25-00-650-005	To Drain the Remaining Fuel from the ACT
AMM 28-42-00-740-003	Interrogation of the FQIS Input Parameters Pages
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)
AMM 31-32-00-860-001	Procedure to Get Access to the SYSTEM REPORT/TEST Menu Page
AMM 31-60-00-860-001	EIS Start Procedure
AMM 34-10-00-860-005	ADIRS Stop Procedure
TSM TASK 28-42-00-03	QUANTITY INDICATING - TASK SUPPORTING DATA

3. Fault Confirmation
Subtask 28-42-00-865-111-A

A. Table of the circuit breakers used in this procedure:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	FUEL/FQI/CHAN/1	1QT	A13
121VU	FUEL/FQI/CHAN/2	2QT	M27

Subtask 28-42-00-710-115-A ** ON A/C NOT FOR ALL

B. Test
(1) Do the Power-on BITE test of the FQI system as follows:
(a) If the FQIS is not energized:
1 Close the C/Bs 1QT and 2QT.
2 Energize the Aircraft Electrical Circuits from the External Power AMM 24-41-00-861-002.
(b) If the FQIS is energized, reset the FQIC as follows:
1 Open the C/Bs 1QT and 2QT.
2 Wait 5 seconds.
3 Close the C/Bs 1QT and 2QT.

NOTE: For the FQIC to do a (new) power-on BITE test, a power supply interrupt (interval) of more than 5 seconds is necessary. This gives the status of the FQIS/FLSS components.

(2) Do the EIS Start Procedure (ECAM only) AMM 31-60-00-860-001.
(3) Make sure that the ADIRS is set to OFF. If necessary, do the ADIRS stop procedure AMM 34-10-00-860-005.

NOTE: This step is important if this procedure is being used to trouble shoot a FQI display (ECAM and FQIS) fluctuation problem. It will disconnect the external acceleration inputs that are used to give pitch and roll.

(4) On the ECAM control panel, push (in) the FUEL P/BSW.
(5) Make sure that the FUEL page shows on the ECAM lower display unit.
(6) Wait 60 seconds.
(7) Continue as follows:

NOTE: The FUEL page FQIs will show XXs in amber color for 35 seconds during the FQIC power-on BITE test and the intercell transfer valves can be seen to move.

(a) Do the procedure to get access to the SYSTEM REPORT/TEST menu page AMM 31-32-00-860-001.
(b) When the SYSTEM REPORT/TEST menu page comes into view, push the line key adjacent to FUEL.
(c) When the FUEL menu page 1 comes into view, push the NEXT PAGE key on the MCDU keyboard to see the FUEL menu page 2.

NOTE: When a menu has more than one page it is shown by the more to come symbol > on the top line.

(d) When the FUEL menu page 2 comes into view, push the line key adjacent to FQIS STATUS.
(8) Examine the FQIS STATUS page and then monitor the FQIs on the ECAM FUEL page and the FQIS indicators.

NOTE: In normal operation the FQI indicators (FQIS and ECAM, FOB and each tank quantity) can increase or decrease by 10 kg/20 lb (which is one unit of the display resolution). If a tank value increases or decreases by 10 kg/20 lb, the total (FOB) will increase or decrease by the same amount.

if no FQIS messages are shown, but the FQIs are seen to change over time (fluctuate), do Para. 4.A.
if the FQIC 3QT message is shown, or the FQIC 3QT message with other FQIS probe messages are shown, do the TSM procedure Fuel Quantity Indication Computer (FQIC) 3QT (Ref. TSM TASK 28-42-00-810-801)
if only FQIS probe messages are shown, trouble-shoot the identified LRUs.

Subtask 28-42-00-710-115-B ** ON A/C NOT FOR ALL

B. Test
(1) To keep the number of computer removals and replacements to a minimum do the Power-on BITE test of the FQI system as follows:
(a) If the FQIS is not energized:
1 Close the C/Bs 1QT and 2QT.
2 Energize the Aircraft Electrical Circuits from the External Power AMM 24-41-00-861-002.
(b) If the FQIS is energized, reset the FQIC as follows:
1 Open the C/Bs 1QT and 2QT.
2 Wait 10 seconds.
3 Close the C/Bs 1QT and 2QT.

NOTE: For the FQIC to do a (new) power-on BITE test, a power supply interrupt (interval) of more than 10 seconds is necessary. This gives the current status of the FQIS/FLSS components.

(2) Do the EIS Start Procedure (ECAM only) AMM 31-60-00-860-001.
(3) Make sure that the ADIRS is set to OFF. If necessary, do the ADIRS stop procedure AMM 34-10-00-860-005.

NOTE: This step is important if this procedure is being used to trouble shoot a FQI display (ECAM and FQIS) fluctuations problem. It will disconnect the external acceleration inputs that are used to give pitch and roll.

(4) On the ECAM control panel, push (in) the FUEL P/BSW.
(5) Make sure that the FUEL page shows on the ECAM lower display unit.
(6) Wait 60 seconds.
(7) Continue as follows:

NOTE: The FUEL page FQIs will show XXs in amber color for 35 seconds during the FQIC power-on BITE test.

(a) Do the procedure to get access to the SYSTEM REPORT/TEST menu page AMM 31-32-00-860-001.
(b) When the SYSTEM REPORT/TEST menu page comes into view, push the line key adjacent to FUEL.
(c) When the FUEL menu page comes into view, push the line key adjacent to FQIS STATUS.
(8) Examine the FQIS STATUS page and then monitor the FQIs on the ECAM FUEL page and the FQIS indicators:

if no FQIS messages are shown, but the FQIs are seen to change over time (fluctuate), do Para. 4.A.
if the FQIC 3QT message is shown, or the FQIC 3QT message with other FQIS probe messages are shown, do the TSM procedure Fuel Quantity Indication Computer (FQIC) 3QT (Ref. TSM TASK 28-42-00-810-801)
if only FQIS probe messages are shown, trouble-shoot the identified LRUs.

4. Fault Isolation
Subtask 28-42-00-810-131-A ** ON A/C NOT FOR ALL

A. Procedure
(1) Do the Interrogation of the FQIS Input Parameters Pages AMM 28-42-00-740-003.
(a) On the MCDU use the print key to make a record of each page (1 thru 3/4) and mark as initial FQIC. Keep for possible (future) reference.
(2) Temporarily replace the FQIC 3QT with a serviceable item AMM 28-42-34-000-001 and AMM 28-42-34-400-001.

NOTE: The step (2) has been included because it is important to make sure that the FQIC 3QT is not the cause of the malfunction before you continue the procedure.

Make sure that the FQIC 3QT to be installed is of the same type as that removed.

(3) Do the Interrogation of the FQIS Input Parameters Pages AMM 28-42-00-740-003.
(a) On the MCDU use the print key to make a record of each page (1 thru 3/4) and mark as temporarily installed FQIC. Keep for possible (future) reference.
(4) If the FQIS and ECAM FQIs do not fluctuate, complete the installation of the FQIC [3QT] AMM 28-42-34-000-001 and AMM 28-42-34-400-001.
(5) If the FQIS and ECAM FQIs continue to fluctuate:
(a) Remove the temporarily installed FQIC 3QT and install the initial FQIC [3QT] AMM 28-42-34-000-001 and AMM 28-42-34-400-001.
(b) Do the test given in Para. 3.B.
(6) If the fault continues, get the MCDU print outs of the FQIS input parameters pages, that you got (recorded) in steps (1) and (3).
(7) Compare the two sets of FQIS input parameters records (paper printouts) and look for a value or values that can cause the FQIs to fluctuate, for example:

compare fuel probe parameters (values - CAD K, DENS, CIC K, INNTEMP, OUTTEMP,PITCH F and ROLL F) with the others given on page 1 for similarity of the fuel conditions and ambient temperatures
compare fuel probe capacitance values with the value of the same probe in the opposite wing or group
look for blank indications (of related capacitance values) for a harness group.

(a) If (on the parameter page 1) the pitch shows PITCH A and ROLL A, go back to Para. 3.B., step (3) and start the procedure from there again.

NOTE: An A, after PITCH and ROLL, shows that the pitch and roll inputs are from the ADIRS. To eliminate the external pitch and roll inputs as the possible cause of the FQI fluctuations, the ADIRS must be set to OFF.
An F, after PITCH and ROLL, shows that the pitch and roll has been made by the FQIS internally.

(8) If necessary, monitor the FQIS input parameters pages at the MCDU screen live. Look for an unusual or incorrect value, an intermittent value, or one that is seen to have unexplained fluctuations.

NOTE: The FQIS input parameter pages are not automatically updated.
To see the operation of the fuel system via the CFDS (FUEL), input parameter pages in real-time the pages must be continually updated. Use the NEXT PAGE control on the MCDU to cycle the pages to update the screen. If this procedure is not used the data will stay as they were at the time of the page (menu option) selection.

(9) Make an analysis from the input parameter results (records made in steps (1), (3), and from the MCDU screen direct in step (8)) with the steps (items) that follow:
(a) If you are not sure of the quality of the aircraft fuel , do all of the work steps (that follow) fully (thoroughly).

NOTE: If you do not fully do the worksteps, you will not remove the fuel related items from the possible causes. These steps are important because poor quality fuel can give you the fault symptoms you have on your aircraft.

1 Defuel all the aircraft tanks AMM 28-25-00-650-001.
a Drain the remaining fuel from all the tanks to make sure that there is no water in the tanks AMM 28-25-00-650-003 (and if applicable AMM 28-25-00-650-005).
b Do a check of the aircraft log to make sure that the fuel-tank microbiological contamination procedures have been obeyed.
c Refuel with fuel of the correct specification AMM 12-11-28-650-003 or AMM 12-11-28-650-004.
d Do the test given in Para. 3.B.
(b) If a fuel probe capacitance value is not with-in range, replace the related LRU. Go to Start Troubleshooting - CFDS for the related Task number.

NOTE: The normal range of fuel probe capacitance values is given in 28-42-00-03 TSM TASK 28-42-00-03.

NOTE: A fuel probe can fail and still stay within its range and/or not be reported on the FQIS STATUS page.

1 Do the test given in Para. 3.B.
(c) If the capacitive values of related fuel probe LRUs attached to a FQIS fuel tank harness are shown blank, fluctuate or are outside the range of a similar group:
1 Do a check of the related fused connector/adaptor and replace, if necessary. (Post Mod 28904/SB28-1087)
2 Do a check of the related aircraft wiring (including the common drive screen) between the FQIC rack-connector and the shorting plug/fused connector as given in a procedure for a fuel probe in the applicable group.
a Repair all the unserviceable wiring and connectors ESPM 2053210.
3 Trouble shoot the related harness as given in a procedure for a fuel probe in the given group.
a If necessary, replace the applicable harness.
4 Trouble shoot the fuel probes on the related harness.
Start with the multi-sensor (CADENSICON, CAPACITANCE INDEX COMPENSATOR), if applicable, fuel probes first.
5 Do the test given in Para. 3.B.

Subtask 28-42-00-810-131-B ** ON A/C NOT FOR ALL

(3) Do the Interrogation of the FQIS Input Parameters Pages AMM 28-42-00-740-003.
(a) On the MCDU use the print key to make a record of each page (1 thru 3/4) and mark as temporarily installed FQIC. Keep for possible (future) reference.
(4) If the FQIS and ECAM FQIs do not fluctuate, complete the installation of the FQIC [3QT] AMM 28-42-34-000-001 and AMM 28-42-34-400-001.
(5) If the FQIS and ECAM FQIs continue to fluctuate:
(a) Remove the temporarily installed FQIC 3QT AMM 28-42-34-000-001 and install the initial FQIC 3QT AMM 28-42-34-400-001.
(b) Do the test given in Para. 3.B.
(6) If the fault continues, get the MCDU print outs of the FQIS input parameters pages, that you got (recorded) in steps (1) and (3).
(7) Compare the two sets of FQIS input parameters records (paper printouts) and look for a value or values that can cause the FQIs to fluctuate, for example:

compare fuel probe parameters (values - K, T, V, KA, KB, DENS, TEMP, PITCH and ROLL) with the others given on page 1 for similarity of the fuel conditions and ambient temperatures
compare fuel probe capacitance values with the value of the same probe in the opposite wing or group
look for blank indications (of related capacitance values) for a harness group.

(8) If necessary, monitor the FQIS input parameters pages live. Look for an unusual or incorrect value, an intermittent value, or one that is seen to have unexplained fluctuations.

NOTE: The FQIS input parameter pages are automatically updated once every 5.5 seconds to let you see the operation of the system in real time.

1 Defuel all the aircraft tanks AMM 28-25-00-650-001.
a Drain the remaining fuel from all the tanks to make sure that there is no water in the tanks AMM 28-25-00-650-003 (and if applicable AMM 28-25-00-650-005).
b Do a check of the aircraft log to make sure that the fuel-tank microbiological contamination procedures have been obeyed.
c Refuel with fuel of the correct specification AMM 12-11-28-650-003 AMM 12-11-28-650-004.
d Do the test given in Para. 3.B.
(b) If a fuel probe capacitance value is not with-in range, replace the related LRU. Go to Start Troubleshooting - CFDS for the related Task number.

NOTE: The normal range of fuel probe capacitance values is given in 28-42-00-03 TSM TASK 28-42-00-03.

NOTE: A fuel probe can fail and still stay within its range and/or not be reported on the FQIS STATUS page.

1 Do the test given in Para. 3.B.
(c) If the capacitive values of related fuel probe LRUs attached to a FQIS fuel tank harness are shown blank, fluctuate or are outside the range of a similar group:
1 Do a check of the related aircraft wiring (including the common drive screen) between the FQIC rack-connector and the shorting plug as given in a procedure for a fuel probe in the given group.
a Repair all the unserviceable wiring and connectors ESPM 2053210.
2 Trouble shoot the related harness as given in a procedure for a fuel probe in the applicable group.
a If necessary, replace the applicable harness.
3 Trouble shoot the fuel probes on the related harness.
Start with the multi-sensor (ULTRA COMP, DUAL COMP), if applicable, fuel probes first.
4 Do the test given in Para. 3.B.

[Rev.8 from Aug 2018] 2026.04.04 04:39:45 UTC