DOC AIRBUS | TSM A320FFQIs Degraded, Malfunction in a W/Tank when Fused Connector Plugs are Installed An Alternative Task for the Connector Plug Only and Caused by Moisture Ingress
TASK 28-42-00-810-875-A
FQIs Degraded, Malfunction in a W/Tank when Fused Connector Plugs are Installed An Alternative Task for the Connector Plug Only and Caused by Moisture Ingress
A. Fixtures, Tools, Test and Support Equipment
B. Referenced Information
3. Fault Confirmation
Subtask 28-42-00-865-112-A ** ON A/C NOT FOR ALL
Subtask 28-42-00-810-132-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:39:45 UTC
FQIs Degraded, Malfunction in a W/Tank when Fused Connector Plugs are Installed An Alternative Task for the Connector Plug Only and Caused by Moisture Ingress
WARNING:
OBEY THE FUEL SAFETY PROCEDURES.
1. Possible Causes- fused connector plug 4041VC-A
- fused connector plug 4042VC-A
- fused connector plug 4043VC-A
- fused connector plug 4044VC-A
A. Fixtures, Tools, Test and Support Equipment
| REFERENCE | QTY | DESIGNATION |
|---|---|---|
| No specific | AR | MULTIMETER - STANDARD |
| REFERENCE | DESIGNATION |
|---|---|
| TSM TASK 28-42-00-810-801-A | Fuel Quantity Indication Computer (FQIC) 3QT |
| TSM TASK 28-42-00-810-873-A | Fuel Quantity Probe - A Malfunction in the Wing Tank when Fused Connector Plugs are Installed - An Alternative Task (procedure) for the Connector Plug Only |
| AMM 05-25-70-200-004 | GENERAL VISUAL INSPECTION OF FALSE SPAR BOX (EWIS) |
| ESPM 2052220 | |
| ESPM 2052240 | |
| AMM 28-42-00-740-003 | Interrogation of the FQIS Input Parameters Pages |
| ASM 284205 | |
| ASM 284206 | |
| ASM 284207 | |
| ASM 284208 | |
| AMM 28-42-43-000-008 | Removal of the Wing Tank Fuel Quantity Indicating Probe Fused/Shorting Plug Connectors |
| AMM 28-42-43-400-008 | Installation of the Wing Tank Fuel Quantity Indicating Probe Fused/Shorting Plug Connectors |
Subtask 28-42-00-865-112-A ** ON A/C NOT FOR ALL
A. Table of the circuit breakers used in this procedure:
Subtask 28-42-00-710-116-A ** ON A/C NOT FOR ALL | PANEL | DESIGNATION | FIN | LOCATION |
|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||
| 49VU | FUEL/FQI/CHAN/1 | 1QT | A13 |
| 121VU | FUEL/FQI/CHAN/2 | 2QT | M27 |
B. Test
(a) If there is moisture ingress of the fused connector, go to step (15) of Para. 4.A.
(4) Examine the Input Parameters Page 2 (FUEL, FQIS PROBE CAPACITANCES) for multiple LRUs shown with an asterisk(*), XXs, or blanks:
4. Fault IsolationNOTE: This task gives an alternative procedure for trouble shooting a degraded FQI display with a reported FQIC (3QT) malfunction. It is related to the wing-tank fused connector plugs only (fault caused by water/moisture ingress into the back of the fused connector.
(1) Do a check for moisture ingress of the applicable fused connector plug 4041VC-A, 4042VC-A, 4043VC-A or 4044VC-A. (a) If there is moisture ingress of the fused connector, go to step (15) of Para. 4.A.
NOTE: This task is related to the TSM procedure (Ref. TSM TASK 28-42-00-810-873) that gives an alternative procedure for trouble shooting a reported wing-tank fuel-probe malfunction for fused connector plugs only (when a single internal fuse has operated).
(2) Make a record of which tank shows degraded: - if a tank shows permanently degraded, go to step (4)
- if no tank shows permanently degraded, go to step (6).
(4) Examine the Input Parameters Page 2 (FUEL, FQIS PROBE CAPACITANCES) for multiple LRUs shown with an asterisk(*), XXs, or blanks:
- if the capacitance values are shown as such, and the FQIC (3QT) message is still shown on the FQIS STATUS page, go to Para. 4.A.
- if the capacitance values are shown correctly, but the FQIC (3QT) message is still shown on the FQIS STATUS page, do the TSM procedure (Ref. TSM TASK 28-42-00-810-801)
- if the capacitance values are shown correctly, and the FQIC (3QT) message is not shown on the FQIS STATUS page, no more maintenance work is necessary.
- intermittent fuel-probe faults reported
- intermittent fuel-tank degraded indications
- intermittent L(R) wing-tank outer-cell under read by up to 400 kg (880 lb) when L(R) fuel-probe 34QT1(2) is reported.
NOTE: The different fault symptoms in this scenario (sequence of events) do not follow a logical pattern or appear to be related.
Subtask 28-42-00-810-132-A ** ON A/C NOT FOR ALL
A. Procedure
(1) Make a record of all the fuel-probes (in the wing-tank identified in Para. 3.B. step (3)) shown with an asterisk(*), XXs, or blank.
(a) If available, use the print function on the MCDU to do this.
(2) Make a comparison of your record of LRUs with the LRUs in the tables that follow:
(3) When you have identified the wing and group that shows a malfunction, open the C/Bs 1QT and 2QT.
(4) Remove the access panels 574BB and 674BB located on the lower surface of the wing (false spar box). These panels are forward of and between flap track 2 and the out board edge of the inner flap AMM 05-25-70-200-004.
(5) Get access through the openings 574BB and 674BB AMM 28-42-43-000-008.
The fused connector plugs are installed below the tank wall connectors 4039VC1 and 4040VC1 (4039VC2 and 4040VC2).
(6) Interchange (swap) the positions of the applicable fused connector plugs 4041VC-A and 4043VC-A (4042VC-A and 4044VC-A) from its original position to the same group of the opposite wing (Ref. the tables in step (2)).
(8) Make a record of which tank shows degraded.
(9) Do the Interrogation of the FQIS Input Parameters Pages AMM 28-42-00-740-003 again.
(11) Make a record of all the fuel-probes, in the wing-tank as identified in step (10).
(a) If available, use the print function on the MCDU to do this.
(12) Compare the initial records with the last records:
(14) Do a wiring test ASM 284205 ASM 284207 ( ASM 284206 ASM 284208), with a MULTIMETER - STANDARD, of the unserviceable fused connector plug as follows:
(a) Do a check of the internal wiring (insulation resistance) between the pins B (common drive) and K (fused common drive return) ESPM 2052220.
(b) Make sure that the insulation resistance is more than 1M ohm (sufficiently high to stop the drive and the drive return from shorting out) ESPM 2052240.
(1) Make a record of all the fuel-probes (in the wing-tank identified in Para. 3.B. step (3)) shown with an asterisk(*), XXs, or blank.
(a) If available, use the print function on the MCDU to do this.
(2) Make a comparison of your record of LRUs with the LRUs in the tables that follow:
| --------------------------------------------------------------------- |
| ! LEFT WING GROUP A - HARNESS 13QT1 - FUSED CONNECTOR PLUG 4041VC-A ! |
| --------------------------------------------------------------------- |
| L CADENSICON 19QT1 |
| L QTY PROBE 21QT1 |
| L QTY PROBE 23QT1 |
| L QTY PROBE 25QT1 |
| L QTY PROBE 27QT1 |
| L QTY PROBE 29QT1 |
| L QTY PROBE 31QT1 |
| L QTY PROBE 33QT1 |
| --------------------------------------------------------------------- |
| ! LEFT WING GROUP B - HARNESS 14QT1 - FUSED CONNECTOR PLUG 4043VC-A ! |
| --------------------------------------------------------------------- |
| L QTY PROBE 22QT1 |
| L QTY PROBE & CIC 24QT1 |
| L QTY PROBE 26QT1 |
| L QTY PROBE 28QT1 |
| L QTY PROBE 30QT1 |
| L QTY PROBE 32QT1 |
| L QTY PROBE 34QT1 |
| ---------------------------------------------------------------------- |
| ! RIGHT WING GROUP A - HARNESS 13QT2 - FUSED CONNECTOR PLUG 4042VC-A ! |
| ---------------------------------------------------------------------- |
| R CADENSICON 19QT2 |
| R QTY PROBE 21QT2 |
| R QTY PROBE 23QT2 |
| R QTY PROBE 25QT2 |
| R QTY PROBE 27QT2 |
| R QTY PROBE 29QT2 |
| R QTY PROBE 31QT2 |
| R QTY PROBE 33QT2 |
| ---------------------------------------------------------------------- |
| ! RIGHT WING GROUP B - HARNESS 14QT2 - FUSED CONNECTOR PLUG 4044VC-A ! |
| ---------------------------------------------------------------------- |
| R QTY PROBE 22QT2 |
| R QTY PROBE & CIC 24QT2 |
| R QTY PROBE 26QT2 |
| R QTY PROBE 28QT2 |
| R QTY PROBE 30QT2 |
| R QTY PROBE 32QT2 |
| R QTY PROBE 34QT2 |
(3) When you have identified the wing and group that shows a malfunction, open the C/Bs 1QT and 2QT.
(4) Remove the access panels 574BB and 674BB located on the lower surface of the wing (false spar box). These panels are forward of and between flap track 2 and the out board edge of the inner flap AMM 05-25-70-200-004.
(5) Get access through the openings 574BB and 674BB AMM 28-42-43-000-008.
The fused connector plugs are installed below the tank wall connectors 4039VC1 and 4040VC1 (4039VC2 and 4040VC2).
(6) Interchange (swap) the positions of the applicable fused connector plugs 4041VC-A and 4043VC-A (4042VC-A and 4044VC-A) from its original position to the same group of the opposite wing (Ref. the tables in step (2)).
NOTE: It is important that the fused connector is swapped with the same group in the opposite wing to make sure that you can see the FQIS degraded indication move to another tanks display. (If you swap the connector with the one in the same wing, the degraded indication will stay at the original tanks location).
(7) Close the C/Bs 1QT and 2QT. (8) Make a record of which tank shows degraded.
(9) Do the Interrogation of the FQIS Input Parameters Pages AMM 28-42-00-740-003 again.
NOTE: This is necessary because when the C/Bs were set to open and the 28VDC removed from the FQIS in step (3) the CFDS display (on the MCDU) will return to the top menu.
(10) Examine (again) the Input Parameters Page 2 (FUEL, FQIS PROBE CAPACITANCES) for multiple LRUs shown with an asterisk(*), XXs, or blanks. (11) Make a record of all the fuel-probes, in the wing-tank as identified in step (10).
(a) If available, use the print function on the MCDU to do this.
(12) Compare the initial records with the last records:
- if the capacitance values shown as such have moved to another group/harness, the degraded tank has moved to the opposite side, and the FQIC (3QT) message is still shown on the FQIS STATUS page, do step (13)
- if the capacitance values are shown correctly, but the FQIC (3QT) message is still shown on the FQIS STATUS page, do the TSM procedure (Ref. TSM TASK 28-42-00-810-801)
- if the capacitance values are shown correctly, and the FQIC (3QT) message is not shown on the FQIS STATUS page, no more maintenance work is necessary.
(14) Do a wiring test ASM 284205 ASM 284207 ( ASM 284206 ASM 284208), with a MULTIMETER - STANDARD, of the unserviceable fused connector plug as follows:
(a) Do a check of the internal wiring (insulation resistance) between the pins B (common drive) and K (fused common drive return) ESPM 2052220.
(b) Make sure that the insulation resistance is more than 1M ohm (sufficiently high to stop the drive and the drive return from shorting out) ESPM 2052240.
NOTE: This is to make sure that only the unserviceable connector plug(s) is/are replaced.
(15) Replace AMM 28-42-43-000-008 and AMM 28-42-43-400-008 the unserviceable: - fused connector plug 4041VC-A
- ( fused connector plug 4042VC-A )
- fused connector plug 4043VC-A
- ( fused connector plug 4044VC-A ).