W DOC AIRBUS | TSM A320F

FLSCU1(2) 7QJ(9QJ)

TASK 28-46-00-810-818-A
FLSCU1(2) 7QJ(9QJ)

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
  • FLSCU-1 [7QJ]
  • FLSCU-2 [9QJ]
  • FQIC [3QT]
  • aircraft wiring
2. Job Set-up Information
 A. Fixtures, Tools, Test and Support Equipment
REFERENCE
QTY
DESIGNATION
No specific
AR
MULTIMETER - STANDARD
No specific
AR
SAFETY BARRIER(S)
 B. Referenced Information
REFERENCE
DESIGNATION
TSM TASK 28-46-00-810-801-A
L(R) Low Level Sensor 15QJ1(2)
TSM TASK 28-46-00-810-802-A
L(R) Low Level Sensor 16QJ1(2)
TSM TASK 28-46-00-810-803-A
L(R) High Level Sensor 17QJ1(2)
TSM TASK 28-46-00-810-804-A
L(R) Low Level Sensor 39QJ1(2)
TSM TASK 28-46-00-810-805-A
Center Tank High Level Sensor 20QJ
TSM TASK 28-46-00-810-806-A
Center Tank Low Level Sensor 21QJ
TSM TASK 28-46-00-810-807-A
L(R) Full Level Sensor 1 23QJ1(2)
TSM TASK 28-46-00-810-808-A
L(R) Underfull Level Sensor 1 24QJ1(2)
TSM TASK 28-46-00-810-809-A
L(R) Underfull Level Sensor 2 25QJ1(2)
TSM TASK 28-46-00-810-810-A
L(R) Underfull Level Sensor 3 26QJ1(2)
TSM TASK 28-46-00-810-811-A
L(R) Full Level Sensor 2 27QJ1(2)
TSM TASK 28-46-00-810-812-A
L(R) Surge Tank Overflow Sensor 28QJ1(2)
TSM TASK 28-46-00-810-815-A
L(R) IDG Shut Off Sensor 38QJ1(2)
TSM TASK 28-46-00-810-816-A
L(R) Low Level Sensor 40QJ1(2)
TSM TASK 28-46-00-810-817-A
Center Tank High Level Dummy Sensor 6QJ
AMM 12-11-28-650-001
General Refuel/Defuel Safety Procedures
AMM 12-11-28-650-002
Refuel/Defuel Safety Procedures for use in the Hangar
AMM 28-00-00-910-001
Fuel Safety Procedures
AWM 281501
AWM 281502
AWM 281503
AWM 281504
AWM 282107
AMM 28-25-00-650-001
Pressure Defuel
AMM 28-25-00-869-001
Fuel Transfer
AMM 28-42-00-740-003
Interrogation of the FQIS Input Parameters Pages
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)
AMM 28-46-00-710-001
Test of the Tank High-Level Sensing-System
AMM 28-46-00-740-001
Functional (BITE) Test
ASM 284601
AWM 284601
ASM 284602
ASM 284603
AWM 284603
ASM 284604
AWM 284606
AWM 284609
AWM 284610
AWM 284612
AMM 28-46-34-000-001
Removal of the Fuel-Level Sensing Control-Unit (FLSCU)
AMM 28-46-34-400-001
Installation of the Fuel-Level Sensing Control-Unit (FLSCU)
3. Fault Confirmation
Subtask 28-46-00-865-073-A
A. Table of the circuit breakers referred to in this procedure:
PANELDESIGNATIONFINLOCATION
** ON A/C NOT FOR ALL
49VUFUEL/XFR VALVE1/WING/R2QPA11
49VUFUEL/XFR VALVE1/WING/L1QPA10
** ON A/C NOT FOR ALL
49VUFUEL/AFT LOW LVL/& OVFL/WING R44QJA11
49VUFUEL/AFT LOW LVL/& OVFL/WING L43QJA10
** ON A/C NOT FOR ALL
121VUFUEL/CTR TK/PUMPS1 AND 2/CTL AND IND32QAR26
121VUFUEL/CTR TK/PUMPS1 AND 2/CTL AND IND31QAR25
** ON A/C NOT FOR ALL
121VUFUEL/XFR VALVE2/WING/R4QPM23
121VUFUEL/XFR VALVE2/WING/L3QPM22
** ON A/C ALL
121VUFUEL/HI/LVL/SPLY1QJL25
** ON A/C NOT FOR ALL
121VUFUEL/CTR TK/L&R XFR/CTL & IND2QLR26
121VUFUEL/CTR TK/L&R XFR/CTL & IND1QLR25
** ON A/C NOT FOR ALL
121VUFUEL/FWD LOW LVL/WING/R45QJM23
121VUFUEL/FWD LOW LVL/WING/L46QJM22
Subtask 28-46-00-740-067-A ** ON A/C NOT FOR ALL
B. Test
   (1) Make sure that the FLSS related TSD for the aircraft is recorded from the FLSCU-1 [7QJ] and FLSCU-2 [9QJ] for faults that have shown in the last leg report AMM 28-42-00-740-007.
NOTE: If the FLSCU TSD shows the fault 1E or 2E (FLSCU 1(2) - Sensor failure with no monitor) on the grid. The FLSCU 1(2) has no sensor fault, but there is a frequent error during an automatic (power on) FQIC FLSS BITE TEST of the sensor channel.
   (2) Do the BITE test of the FLSS AMM 28-46-00-740-001.
   (3) Examine the FLSS STATUS Page.
   (4) If the message 284634 FLSCU1(2) 7QJ(9QJ):
     (a) Is not shown, go to para 4. step (2).
     (b) Is shown, go to Para. 4. step (3).
If the message is followed by a sensor message or sensor messages, do this Task before troubleshooting the sensor(s).
NOTE: You can get data from the:
  • Description and Operation (D and O) section of the Aircraft Maintenance Manual (AMM) Chap. 28-46-00, the Fuel Level Sensing System (FLSS)
  • Trouble Shooting Manual (TSM) - Task Supporting Data (Ref. P. Block 301)
  • Aircraft Schematic Manual (ASM) ASM 284601 ASM 284602 ASM 284603 and ASM 284604.
NOTE: You can get more Trouble-shooting data from the CFDS(FUEL):
NOTE: OPTIONAL TESTING:
Where a PSD A320-3 Fuel Level Sensing System Test Set is available, all of the tank-mounted FLSS components can be tested, and the FLSCU relay outputs simulated. Access to the system is gained by removing the FLSCU (one of two) and installing the PSD A320-3.
Subtask 28-46-00-740-067-B ** ON A/C NOT FOR ALL
B. Test
   (1) Do the BITE test of the FLSS AMM 28-46-00-740-001.
   (2) Examine the FLSS STATUS page.
   (3) If the message 284634 FLSCU1(2) 7QJ(9QJ):
     (a) Is not shown, go to Para. 4. step (2).
     (b) Is shown, go to Para. 4. step (3).
If the message is followed by a sensor message or sensor messages, do this Task before troubleshooting the sensor(s).
NOTE: You can get data from the:
  • Description and Operation (D and O) section of the Aircraft Maintenance Manual (AMM) Chap. 28-46-00, the Fuel Level Sensing System (FLSS)
  • Trouble Shooting Manual (TSM) - Task Supporting Data (Ref. P. Block 301)
  • Aircraft Schematic Manual (ASM) ASM 284601 ASM 284602 ASM 284603 and ASM 284604.
NOTE: You can get more Trouble-shooting data from the CFDS(FUEL):
NOTE: OPTIONAL TESTING:
Where a PSDA321-1 Test Set is available, all of the tank-mounted FLSS components can be tested.
Where a PSDA321-4 Discrete Indication Switch Unit (DISU), and a PSDA321-2 FLSCU Breakout Unit is available the FLSCU relay outputs can be simulated.
Where a PSDA321-4 DISU, and a PSDA321- 3 FQIC Breakout Unit is available the status of discrete outputs originating from the FLSCU can be displayed.
4. Fault Isolation
Subtask 28-46-00-810-067-C ** ON A/C NOT FOR ALL
A. Procedure
   (1) Make sure that the Aircraft Pitch and Roll are 0 +2 deg or -2 deg (0.0000 +2.0000 deg or -2.0000 deg).
   (2) If a sensor or an FLSCU is shown as failed after the commanded BITE, go to step (3).
NOTE: If there are no faults from the FLSS COMMANDED BITE it is possible that the fault is related to a failure of a sensor and not the Level Sensor Amplifier.
     (a) Do a check of the LAST LEG REPORT and PREVIOUS LEGS REPORTS to make sure the fault is hard:
NOTE: If there is a hard fault, the defective FLSCU will be shown in other previous reports.
     (b) Do a transfer of fuel until the L(R) wing tanks are empty AMM 28-25-00-869-001.
     (c) Make sure that the refuel panel door 192MB/522KB/622KB is open, or (if installed) the cockpit refuel PWR P/BSW (23QU) is set to on.
     (d) If the faults shown are 1E or 2E (Sensor Failure with no Monitor) do the steps that follow:
       1 Make a record of the FQIC discrete parameters AMM 28-42-00-740-003.
       2 Identify the state of each of the low level sensors from the input parameters.
       3 Do a transfer of fuel to the applicable fuel tank so that the FQIC displays tank fuel quantity above the sensor trip fuel quantity AMM 28-25-00-869-001.
       4 Do a check on the FQIC discrete parameters that the applicable sensor is in the WET state. See table below:
NOTE: A high Level Sensor will show a default status WET if not powered. To power the High-level sensors, open the refuel panel door, or set cockpit refuel (if fitted).
NOTE: These sensors require care when you change them to the WET state in order to prevent a fuel spill. Refer to Para. 4. B.
NOTE: The fuel quantity at which the level sensors change state is related to the density of the fuel used. The values in the table below are calculated with a density of 0.785 (SG). For a higher density these values will increase, for a lower density these values will decrease. When it is not known if a sensor has failed, increase the fuel quantity above the level of the location of the sensor.

FIN
Sensor Description
Fuel QTY
FLSCU /CH
CFDS BIT
STATE 1
STATE 0
6QJ
Dummy sensor
----
FLSCU 2/7
G4
DRY
FAILED
15QJ1
Left wing low level
1410
FLSCU 2/5
E4
WET
NOT WET
15QJ2
Right wing low level
1410
FLSCU 1/5
E3
WET
NOT WET
16QJ1
Left wing low level
770
FLSCU 1/1
A3
WET
NOT WET
16QJ2
Right wing low level
770
FLSCU 2/1
A4
WET
NOT WET
17QJ1
Left wing high level
6120
FLSCU 1/3
C3
DRY
NOT DRY
17QJ2
Right wing high level
6120
FLSCU 2/3
C4
DRY
NOT DRY
20QJ
Centre high level
6500
FLSCU 1/7
G3
DRY
NOT DRY
21QJ
Centre low level
150
FLSCU 1/6
F3
DRY
NOT DRY
22QJ
Centre low level
150
FLSCU 2/6
F4
DRY
NOT DRY
23QJ1
Left inner full
2760
FLSCU 1/11
K3
NOT WET
WET
23QJ2
Right inner full
2760
FLSCU 2/11
K4
NOT WET
WET
24QJ1
Left inner under full
1940
FLSCU 1/13
M3
NOT WET
WET
24QJ2
Right inner under full
1940
FLSCU 2/13
M4
NOT WET
WET
25QJ1
Left inner under full
5280
FLSCU 1/14
N3
NOT WET
WET
25QJ2
Right inner underful
5280
FLSCU 2/14
N4
NOT WET
WET
26QJ1
Left inner underful
5750
FLSCU 1/15
P3
NOT WET
WET
26QJ2
Right inner underfull
5750
FLSCU 2/15
P4
NOT WET
WET
27QJ1
Left wing inner full
5970
FLSCU 1/12
P3
NOT WET
WET
27QJ2
Right wing inner full
5970
FLSCU 2/12
P4
NOT WET
WET
28QJ1
Left wing surge
---
FLSCU 1/4
D3
DRY
NOT DRY
28QJ2
Right wing surge
---
FLSCU 2/4
D4
DRY
NOT DRY
38QJ1
Left wing low level
290
FLSCU 1/10
J3
NOT WET
WET
38QJ2
Right wing low level
290
FLSCU 2/10
J4
NOT WET
WET
39QJ1
Left wing low level
770
FLSCU 2/2
B4
WET
NOT WET
39QJ2
Right wing low level
770
FLSCU 1/2
B3
WET
NOT WET
40QJ1
Left wing low level
1410
FLSCU 1/8
H3
WET
NOT WET
40QJ2
Right wing low level
1410
FLSCU 2/8
H4
WET
NOT WET
     (e) If a sensor is shown as WET when NOT WET or NOT WET when WET, the sensor could be failed. Do the relevant troubleshooting procedure:
     (f) If the fault continues go to Para. (3).
   (3) If the two FLSCUs are shown as failed in the commanded BITE:
     (a) Replace FLSCU-1 [7QJ] and FLSCU-2 [9QJ] , AMM 28-46-34-000-001 and AMM 28-46-34-400-001.
     (b) Do the test given in Para. 3. B.
     (c) Go to step (6).
   (4) If one FLSCU only is shown as failed in the commanded BITE:
     (a) Interchange FLSCUs, AMM 28-46-34-000-001 and AMM 28-46-34-400-001.
     (b) Do the test given in Para. 3.B.
     (c) Go to step (6).
   (5) If the message changes sides:
     (a) Replace the FLSCU-1(2) 7QJ(9QJ) that shows the message AMM 28-46-34-000-001 and AMM 28-46-34-400-001.
     (b) Do the test given in Para. 3.B.
     (c) Go to step (6).
   (6) If the fault continues, and the CFDS shows the original message:
     (a) Do a check again of the FQIC discrete parameters to make sure that the level sensors are in the correct state.
       1 If any of the below sensors are failed, do the applicable maintenance procedure:
  • AMM 28-46-15 for 15QJ1/2, 16QJ1/2, 17QJ1/2, 20QJ, 21QJ, 22QJ, 23QJ1/2, 24QJ1/2, 25QJ1/2 26QJ1/2 or 27QJ1/2.
  • AMM 28-46-16 for 28QJ1/2.
  • AMM 28-46-19 for 38QJ1/2.
       2 If all input parameters show the correct state temporarily replace the FQIC (3QT) with a serviceable item AMM 28-42-34-000-001 and AMM 28-42-34-400-001.
   (7) If the message FLSCU-1(2) 7QJ(9QJ) is not shown:
   (8) If the message FLSCU-1(2) 7QJ(9QJ) is shown:
   (9) Make sure that the REFUEL panel door 192MB/522KB/622KB is open or (if installed) the cockpit refuel PWR P/BSW (23QU) is set to on.
NOTE: This step is necessary to energize the 28VDC FUELLING BUS 1, 501PP, that is the source of the 28VDC (HIGH) supply to each FLSCU. The other three 28VDC supplies to each FLSCU are permanently available from the related fuel subsystem C/Bs.
   (10) Use the procedure AMM 28-46-00-710-001 and do a test of the HI LVL lights, do not include Para. 4.B.
   (11) If during step (10):
     (a) A (any) HI LVL light comes on, go to step (12).
NOTE: This shows the 28VDC FUELLING BUS 1, 501PP is energized and the 28VDC (HIGH) supply is available through the closed C/B-FUEL/HI/LVL/SPLY (1QJ).
     (b) No HI LVL lights come on, do the applicable troubleshooting procedure.
   (12) Use a MULTIMETER - STANDARD do a check for each of the four 28VDC supply inputs at the FLSCU-1(2) 7QJ(9QJ) rack connector as shown in the table that follows.
If a 28VDC supply is not available go to the step given.

If the two 28VDC (HIGH) supplies are NOT correct go to step (21).

If all the 28VDC supplies are correct go to step (22).
NOTE: The FLSCUs are energized from four discrete 28VDC sources.
The 28VDC supplies are applied to channels within each FLSCU as follows.

28VDC (LOW-A) LS1, LS4 and LS8

28VDC (LOW-B) LS2, LS5

28VDC (HIGH) LS3, LS7

28VDC (LOGIC) LS6, LS11, LS12, LS13, LS14, LS15, T1, T2, LOGIC 1, and 2.

There is a FLSCU level sense (LS) channel to FLSS sensor FIN cross reference in step (24).
LRU/SUPPLY
FLSCU-1 CONNECTOR AND PIN
FLSCU-2 CONNECTOR AND PIN
IF NO 28VDC GO TO STEP
IF FAILS BOTH TESTS MARKED * GO TO STEP
FLSCU-1 28VDC (LOW-A)
AA-1A
(13)
FLSCU-1 28VDC (LOW-B)
AA-1C
(14)
FLSCU-1 28VDC (HIGH)
AA-1B *
(15)
(21)
FLSCU-1 28VDC (LOGIC)
AA-1D
(16)
FLSCU-2 28VDC (LOW-A)
AA-1A
(17)
FLSCU-2 28VDC (LOW-B)
AA-1C
(18)
FLSCU-2 28VDC (HIGH)
AA-1B *
(19)
(21)
FLSCU-2 28VDC (LOGIC)
AA-1D
(20)
   (13) Do a check of the aircraft wiring AWM 281501 between the FLSCU-1 rack connector AA, pin 1A and the C/B-FUEL/XFR VALVE1/WING/L (1QP).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (14) Do a check of the aircraft wiring AWM 281504 between the FLSCU-1 rack connector AA, pin 1C and the C/B-FUEL/XFR VALVE2/WING/R (4QP).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (15) Do a check of the aircraft wiring AWM 284601 between the FLSCU-1 rack connector AA, pin 1B and the terminal block 202VT, terminal 1S.
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (16) Do a check of the aircraft wiring AWM 282107 between the FLSCU-1 rack connector AA, pin 1D and the C/B-FUEL/CTR TK/PUMPS1 & 2/CTL & IND (31QA).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (17) Do a check of the aircraft wiring AWM 281502 between the FLSCU-2 rack connector AA, pin 1A and the C/B-FUEL/XFR VALVE1/WING/R (2QP).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (18) Do a check of the aircraft wiring AWM 281503 between the FLSCU-2 rack connector AA, pin 1C and the C/B-FUEL/XFR VALVE2/WING/L (3QP).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (19) Do a check of the aircraft wiring AWM 284601 between the FLSCU-2 rack connector AA, pin 1B and the terminal block 202VT, terminal 1U.
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (20) Do a check of the aircraft wiring AWM 282107 between the FLSCU-2 rack connector AA, pin 1D and the C/B-FUEL/CTR TK/PUMPS1 & 2/CTL & IND (32QA).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (21) Do a check of the aircraft wiring AWM 284601 between the C/B FUEL/HI/LVL/SPLY (1QJ) and the terminal block 202VT, terminal 1T.
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (22) Do a check of the aircraft wiring AWM 284601 (FLSCU-1 sensor failure monitor line) between the FLSCU-1 rack connector AB, pin 3B and the FQIC rack connector AB, pin 6H or (aircraft wiring (FLSCU-2 sensor failure monitor line) between the FLSCU-2 rack connector AB, pin 3B and the FQIC rack connector AB, pin 15H).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (23) Do a check of the aircraft wiring (FLSS BITE test command lines) between the FQIC rack connector and the FLSCU-1(2) rack connector, as shown in the table that follows:
NOTE: There are eight discrete TEST lines between the FQIC and the FLSS, four TEST lines going to each FLSCU.
LRU BITE TEST WIRE
FQIC CONNECTOR AND PIN
FLSCU-1 CONNECTOR AND PIN
FLSCU-2 CONNECTOR AND PIN
FLSCU-1 BITE 1 TEST
AB-14F
AA-15B
FLSCU-1 BITE 2 TEST
AB-14E
AA-15A
FLSCU-1 BITE 3 TEST
AB-15F
AA-15C
FLSCU-1 BITE 4 TEST
AB-15E
AA-15D
FLSCU-2 BITE 1 TEST
AB-12F
AA-15B
FLSCU-2 BITE 2 TEST
AB-12E
AA-15A
FLSCU-2 BITE 3 TEST
AB-13F
AA-15C
FLSCU-2 BITE 4 TEST
AB-13E
AA-15D
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (24) Do a check of the aircraft wiring (level sense (LS) channel output lines) between the FLSCU-1(2) rack connector and the FQIC rack connector AWM 284601, AWM 284603, AWM 284606, AWM 284609, AWM 284610 and AWM 284612, as shown in the table that follows.
NOTE: There are thirty six discrete level sense (LS) channel output lines between the FLSS and the FQIC, eighteen output lines from each FLSCU.
LRU/CHANNEL OUTPUT WIRE
SENSOR FIN
FLSCU-1 CONNECTOR AND PIN
FLSCU-2 CONNECTOR AND PIN
FQIC CONNECTOR AND PIN
FLSCU-1 LS1
16QJ1
AB-1A
AC-4D
FLSCU-1 LS2
39QJ2
AB-5A
AC-4C
FLSCU-1 LS3
17QJ1
AB-2A
AC-4H
FLSCU-1 LS4
28QJ1
AB-1B
AC-4G
FLSCU-1 LS5
15QJ2
AB-5B
AC-3B
FLSCU-1 LS6
21QJ
AB-2B
AC-3A
FLSCU-1 LS7
20QJ
AB-3A
AC-3K
FLSCU-1 LS8
40QJ1
AB-4A
AC-3J
FLSCU-1 LS10
38QJ1
AB-1C
AC-3D
FLSCU-1 LS11
23QJ1
AB-2C
AC-3C
FLSCU-1 LS12
27QJ1
AB-3C
AC-3H
FLSCU-1 LS13
24QJ1
AB-1D
AC-3G
FLSCU-1 LS14
25QJ1
AB-2D
AC-2B
FLSCU-1 LS15
26QJ1
AB-3D
AC-2A
FLSCU-1 T1
29QJ1
AB-4C
AC-2J
FLSCU-1 T2
41QJ
AB-4D
AC-2D
FLSCU-1 LOGIC 1
7QJ
AB-5C
AC-4B
FLSCU-1 LOGIC 2
7QJ
AB-5D
AC-4A
FLSCU-2 LS1
16QJ2
AB-1A
AC-2G
FLSCU-2 LS2
39QJ1
AB-5A
AC-1B
FLSCU-2 LS3
17QJ2
AB-2A
AC-1A
FLSCU-2 LS4
28QJ2
AB-1B
AC-1K
FLSCU-2 LS5
15QJ1
AB-5B
AC-1J
FLSCU-2 LS6
22QJ
AB-2B
AC-1D
FLSCU-2 LS7
6QJ
AB-3A
AC-1C
FLSCU-2 LS8
40QJ2
AB-4A
AC-1H
FLSCU-2 LS10
38QJ2
AB-1C
AC-1G
FLSCU-2 LS11
23QJ2
AB-2C
AC-2E
FLSCU-2 LS12
27QJ2
AB-3C
AC-1E
FLSCU-2 LS13
24QJ2
AB-1D
AC-1F
FLSCU-2 LS14
25QJ2
AB-2D
AC-2F
FLSCU-2 LS15
26QJ2
AB-3D
AC-4E
FLSCU-2 T1
29QJ2
AB-4C
AC-3F
FLSCU-2 T2
42QJ
AB-4D
AC-4F
FLSCU-2 LOGIC 1
9QJ
AB-5C
AC-2C
FLSCU-2 LOGIC 2
9QJ
AB-5D
AC-2H
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
Subtask 28-46-00-810-127-B ** ON A/C NOT FOR ALL
B. Over fuelling to WET the wing full sensors and the surge tank sensors
WARNING: OBEY THE FUEL SAFETY PROCEDURES.
   (1) As necessary, use the applicable SAFETY BARRIERS, specified by the operator's instructions and your local regulations.
   (2) You must obey the fuel safety procedures AMM 28-00-00-910-001 when you work on the fuel system.
   (3) You must obey the safety procedures when fueling the aircraft AMM 12-11-28-650-001 and AMM 12-11-28-650-002.
   (4) Put a container (example, barrel -42 gal) under the applicable NACA vent(s).
   (5) Make sure that a maintenance person stays in the cockpit to turn off the centre tank pumps if:
  • CTR TK PUMP LOW PRESSURE WARNING is generated to prevent dry running of the pump
  • Fuel flows from the outer tank NACA vents.
   (6) On the fuel control panel (40VU), set the L TK PUMPS 1 and R TK PUMPS 1 P/BSWs to the ON position (pushed in).
   (7) On the fuel control panel (40VU), make sure that the XFEED P/BSW is released out.
   (8) On the fuel control panel (40VU), set the CTR TK L XFR and the CTR TK R XFR P/BSWs to the ON position (pushed in).
   (9) On the Refuel/Defuel control panel (800VU), hold the TEST switch in the HI LVL position.
NOTE: Monitor the fuel transfer from the centre tank to the applicable wing tank until you get the correct fuel quantity.
   (10) Make a record of the FQIC discrete parameters AMM 28-42-00-740-003.
   (11) If the wing full sensors 27QJ1(2) or the wing surge sensors 28QJ1(2) are not indicated in the WET state and fuel flows from the outer tank NACA vent(s):
     (a) On the fuel control panel (40VU):
  • Set the L TK PUMPS 1 and R TK PUMPS 1 P/BSWs to the OFF position (released out)
  • Set the CTR TK L XFR and the CTR TK R XFR P/BSWs to the OFF position (released out).
     (b) Do the applicable troubleshooting given in the Para. 4. A. (d).
   (12) If the wing full sensors 27QJ1(2) or the wing surge sensors 28QJ1(2) are indicated in the WET state:
     (a) On the fuel control panel (40VU):
  • Set the L TK PUMPS 1 and R TK PUMPS 1 P/BSWs to the OFF position (released out)
  • Set the CTR TK L XFR and the CTR TK R XFR P/BSWs to the OFF position (released out).
     (b) Do a pressure defuel procedure AMM 28-25-00-650-001.
Subtask 28-46-00-810-067-D ** ON A/C NOT FOR ALL
C. Procedure
   (1) Make sure that the Aircraft Pitch and Roll are 0 +2 deg or -2 deg (0.0000 +2.0000 deg or -2.0000 deg).
   (2) If a sensor or an FLSCU is shown as failed after the commanded BITE, go to step (3).
NOTE: If there are no faults from the FLSS COMMANDED BITE it is possible that the fault is related to a failure of a sensor and not the Level Sensor Amplifier.
     (a) Do a check of the LAST LEG REPORT and PREVIOUS LEGS REPORTS to make sure the fault is hard:
NOTE: If there is a hard fault, the defective FLSCU will be shown in other previous reports.
     (b) Do a transfer of fuel untill the L(R) wing tanks are empty AMM 28-25-00-869-001.
     (c) Make sure that the refuel panel door 192MB/522KB/622KB is open, or (if installed) the cockpit refuel PWR P/BSW (23QU) is set to on.
     (d) If the faults shown are 1E or 2E (Sensor Failure with no Monitor) do the steps that follow:
       1 Make a record of the FQIC discrete parameters AMM 28-42-00-740-003.
       2 Identify the state of each of the low level sensors from the input parameters.
       3 Do a transfer of fuel to the applicable fuel tank so that the FQIC displays tank fuel quantity above the sensor trip fuel quantity AMM 28-25-00-869-001.
       4 Do a check on the FQIC discrete parameters that the applicable sensor is in the WET state. See table below:
NOTE: A high Level Sensor will show a default status WET if not powered. To power the High-level sensors, open the refuel panel door, or select cockpit refuel (if fitted).
NOTE: These sensors require care when you change them to the WET state in order to prevent a fuel spill. Refer to Para. 4. B.
NOTE: The fuel quantity at which the level sensors change state is related to the density of the fuel used. The values in the table below are calculated with a density of 0.785 (SG). For a higher density these values will increase, for a lower density these values will decrease. When it is not known if a sensor has failed, increase the fuel quantity above the level of the location of the sensor.

FIN
Sensor Description
Fuel QTY
FLSCU /CH
CFDS BIT
STATE 1
STATE 0
6QJ
Dummy sensor
---
FLSCU 2/7
L1
DRY
FAILED
15QJ1
Left wing low level
770
FLSCU 2/5
L6
WET
NOT WET
15QJ2
Right wing low level
770
FLSCU 2/1
M7
WET
NOT WET
16QJ1
Left wing low level
770
FLSCU 1/1
P3
WET
NOT WET
16QJ2
Right wing low level
770
FLSCU 1/5
P4
WET
NOT WET
17QJ1
Left wing high level
5430
FLSCU 1/3
N3
DRY
NOT DRY
17QJ2
Right wing high level
5430
FLSCU 2/3
J3
DRY
NOT DRY
20QJ
Center high level
6470
FLSCU 1/7
N4
DRY
NOT DRY
21QJ
Center low level
160
FLSCU 1/6
P7
DRY
NOT DRY
22QJ
Center low level
160
FLSCU 2/6
J4
DRY
NOT DRY
23QJ1
Left inner full
2770
FLSCU 1/11
P5
WET
NOT WET
23QJ2
Right inner full
2770
FLSCU 2/12
J5
WET
NOT WET
24QJ1
Left inner under full
1770
FLSCU 1/13
N5
WET
NOT WET
24QJ2
Right inner under full
1770
FLSCU 2/13
L8
WET
NOT WET
25QJ1
Left inner under full
4590
FLSCU 1/14
M2
WET
NOT WET
25QJ2
Right inner underful
4590
FLSCU 2/14
J6
WET
NOT WET
26QJ1
Left inner underful
5030
FLSCU 1/15
N1
WET
NOT WET
26QJ2
Right inner underfull
5030
FLSCU 2/15
L3
WET
NOT WET
27QJ1
Left wing inner full
5570
FLSCU 1/12
P8
WET
NOT WET
27QJ2
Right wing inner full
5570
FLSCU 2/12
L2
WET
NOT WET
28QJ1
Left wing surge
---
FLSCU 1/4
N8
DRY
NOT DRY
28QJ2
Right wing surge
---
FLSCU 2/4
M8
DRY
NOT DRY
38QJ1
Left wing low level
270
FLSCU 1/10
M1
WET
NOT WET
38QJ2
Right wing low level
270
FLSCU 2/10
L7
WET
NOT WET
39QJ1
Left wing low level
750
FLSCU 2/2
L5
WET
NOT WET
39QJ2
Right wing low level
750
FLSCU 1/2
P6
WET
NOT WET
     (e) If a sensor is shown as WET when NOT WET or NOT WET when WET, the sensor could be failed. Do the relevant troubleshooting procedure:
     (f) If the fault continues go to Para. (3).
   (3) If the two FLSCUs are shown as failed in the commanded BITE:
     (a) Replace FLSCU-1 [7QJ] and FLSCU-2 [9QJ] , AMM 28-46-34-000-001 and AMM 28-46-34-400-001.
     (b) Do the test given in Para. 3. B.
     (c) Go to step (6).
   (4) If one FLSCU only is shown as failed in the commanded BITE:
     (a) Interchange FLSCUs, AMM 28-46-34-000-001 and AMM 28-46-34-400-001.
     (b) Do the test given in Para. 3.B.
     (c) Go to step (6).
   (5) If the message changes sides:
     (a) Replace the FLSCU-1(2) 7QJ(9QJ) that shows the message AMM 28-46-34-000-001 and AMM 28-46-34-400-001.
     (b) Do the test given in Para. 3.B.
     (c) Go to step (6).
   (6) If the fault continues, and the CFDS shows the original message:
     (a) Do a check again of the FQIC discrete parameters to make sure that the level sensors are in the correct state.
       1 If any of the below sensors are failed, do the applicable maintenance procedure:
  • AMM 28-46-15 for 15QJ1/2, 16QJ1/2, 17QJ1/2, 20QJ, 21QJ, 22QJ, 23QJ1/2, 24QJ1/2, 25QJ1/2 26QJ1/2 or 27QJ1/2.
  • AMM 28-46-16 for 28QJ1/2.
  • AMM 28-46-19 for 38QJ1/2.
       2 If all input parameters show the correct state temporarily replace the FQIC (3QT) with a serviceable item AMM 28-42-34-000-001 and AMM 28-42-34-400-001.
   (7) If the message FLSCU-1(2) 7QJ(9QJ) is not shown:
   (8) If the message FLSCU-1(2) 7QJ(9QJ) is shown:
   (9) Make sure that the REFUEL panel door 192MB/522KB/622KB is open or (if installed) the cockpit refuel PWR P/BSW (23QU) is set to on.
NOTE: This step is necessary to energize the 28VDC FUELLING BUS 1, 501PP, that is the source of the 28VDC (HIGH) supply to each FLSCU. The other three 28VDC supplies to each FLSCU are permanently available from the related fuel subsystem C/Bs.
   (10) Use the procedure AMM 28-46-00-710-001 and do a test of the HI LVL lights, do not include Para. 4.B.
   (11) If during step (10):
     (a) A HI LVL light comes on, go to step (12).
NOTE: This shows the 28VDC FUELLING BUS 1, 501PP is energized and the 28VDC (HIGH) supply is available through the closed C/B-FUEL/HI/LVL/SPLY (1QJ).
     (b) No HI LVL lights come on, to troubleshoot the fault do the relevant troubleshooting procedure.
   (12) Use a MULTIMETER - STANDARD do a check for each of the four 28VDC supply inputs at the FLSCU-1(2) 7QJ(9QJ) rack connector as shown in the table that follows.
If a 28VDC supply is not available go to the step given.

If the two 28VDC (HIGH) supplies are NOT correct go to step (21).

If all the 28VDC supplies are correct go to step (22).
NOTE: The FLSCUs are energized from four discrete 28VDC sources.
The 28VDC supplies are applied to channels within each FLSCU as follows.

28VDC (LOW-A) LS1, LS4

28VDC (LOW-B) LS2, LS5

28VDC (HIGH) LS3, LS7

28VDC (LOGIC) LS6, LS11, LS12, LS13, LS14, LS15, T1, T2, LOGIC 1, and 2.

There is a FLSCU level sense (LS) channel to FLSS sensor FIN cross reference in step (24).
LRU/SUPPLY
FLSCU-1 CONNECTOR AND PIN
FLSCU-2 CONNECTOR AND PIN
IF NO 28VDC GO TO STEP
IF FAILS BOTH TESTS MARKED * GO TO STEP
FLSCU-1 28VDC (LOW-A)
AA-1A
(13)
FLSCU-1 28VDC (LOW-B)
AA-1C
(14)
FLSCU-1 28VDC (HIGH)
AA-1B *
(15)
(21)
FLSCU-1 28VDC (LOGIC)
AA-1D
(16)
FLSCU-2 28VDC (LOW-A)
AA-1A
(17)
FLSCU-2 28VDC (LOW-B)
AA-1C
(18)
FLSCU-2 28VDC (HIGH)
AA-1B *
(19)
(21)
FLSCU-2 28VDC (LOGIC)
AA-1D
(20)
   (13) Do a check of the aircraft wiring AWM 281501 between the FLSCU-1 rack connector AA, pin 1A and the C/B-FUEL/XFR VALVE1/WING/L (1QP).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (14) Do a check of the aircraft wiring AWM 281504 between the FLSCU-1 rack connector AA, pin 1C and the C/B-FUEL/XFR VALVE2/WING/R (4QP).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (15) Do a check of the aircraft wiring AWM 284601 between the FLSCU-1 rack connector AA, pin 1B and the terminal block 202VT, terminal 1S.
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (16) Do a check of the aircraft wiring AWM 282107 between the FLSCU-1 rack connector AA, pin 1D and the C/B-FUEL/CTR TK/PUMPS1 & 2/CTL & IND (31QA).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (17) Do a check of the aircraft wiring AWM 281502 between the FLSCU-2 rack connector AA, pin 1A and the C/B-FUEL/XFR VALVE1/WING/R (2QP).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (18) Do a check of the aircraft wiring AWM 281503 between the FLSCU-2 rack connector AA, pin 1C and the C/B-FUEL/XFR VALVE2/WING/L (3QP).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (19) Do a check of the aircraft wiring AWM 284601 between the FLSCU-2 rack connector AA, pin 1B and the terminal block 202VT, terminal 1U.
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (20) Do a check of the aircraft wiring AWM 282107 between the FLSCU-2 rack connector AA, pin 1D and the C/B-FUEL/CTR TK/PUMPS1 & 2/CTL & IND (32QA).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (21) Do a check of the aircraft wiring AWM 284601 between the C/B FUEL/HI/LVL/SPLY (1QJ) and the terminal block 202VT, terminal 1T.
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (22) Do a check of the aircraft wiring AWM 284601 (FLSCU-1 sensor failure monitor line) between the FLSCU-1 rack connector AB, pin 3B and the FQIC rack connector AB, pin 6H or (aircraft wiring (FLSCU-2 sensor failure monitor line) between the FLSCU-2 rack connector AB, pin 3B and the FQIC rack connector AB, pin 15H).
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (23) Do a check of the aircraft wiring (FLSS BITE test command lines) between the FQIC rack connector and the FLSCU-1(2) rack connector, as shown in the table that follows.
NOTE: There are eight discrete TEST lines between the FQIC and the FLSS, four TEST lines going to each FLSCU.
LRU BITE TEST WIRE
FQIC CONNECTOR AND PIN
FLSCU-1 CONNECTOR AND PIN
FLSCU-2 CONNECTOR AND PIN
FLSCU-1 BITE 1 TEST
AB-7H
AA-15B
FLSCU-1 BITE 2 TEST
AB-7J
AA-15A
FLSCU-1 BITE 3 TEST
AB-8H
AA-15C
FLSCU-1 BITE 4 TEST
AB-7K
AA-15D
FLSCU-2 BITE 1 TEST
AB-10H
AA-15B
FLSCU-2 BITE 2 TEST
AB-8K
AA-15A
FLSCU-2 BITE 3 TEST
AB-9J
AA-15C
FLSCU-2 BITE 4 TEST
AB-9H
AA-15D
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
   (24) Do a check of the aircraft wiring (level sense (LS) channel output lines) between the FLSCU-1(2) rack connector and the FQIC rack connector AWM 284601, AWM 284603, AWM 284606, AWM 284609, AWM 284610, and AWM 284612, as shown in the table that follows.
NOTE: There are thirty four discrete level sense (LS) channel output lines between the FLSS and the FQIC, seventeen output lines from each FLSCU.
LRU/CHANNEL OUTPUT WIRE
SENSOR FIN
FLSCU-1 CONNECTOR AND PIN
FLSCU-2 CONNECTOR AND PIN
FQIC CONNECTOR AND PIN
FLSCU-1 LS1
16QJ1
AB-1A
AB-2J
FLSCU-1 LS2
39QJ2
AB-5A
AB-4G
FLSCU-1 LS3
17QJ1
AB-2A
AB-6G
FLSCU-1 LS4
28QJ1
AB-1B
AB-2K
FLSCU-1 LS5
16QJ2
AB-5B
AB-5G
FLSCU-1 LS6
21QJ
AB-2B
AB-3H
FLSCU-1 LS7
20QJ
AB-3A
AB-7G
FLSCU-1 LS8
NA
Not used
FLSCU-1 LS10
38QJ1
AB-1C
AB-3K
FLSCU-1 LS11
23QJ1
AB-2C
AB-3J
FLSCU-1 LS12
27QJ1
AB-3C
AB-4H
FLSCU-1 LS13
24QJ1
AB-1D
AB-4J
FLSCU-1 LS14
25QJ1
AB-2D
AB-4K
FLSCU-1 LS15
26QJ1
AB-3D
AB-5H
FLSCU-1 T1
29QJ1
AB-4C
AB-5J
FLSCU-1 T2
30QJ1
AB-4D
AB-5K
FLSCU-1 LOGIC 1
7QJ
AB-5C
AB-6J
FLSCU-1 LOGIC 2
7QJ
AB-5D
AB-6K
FLSCU-2 LS1
15QJ2
AB-1A
AB-9K
FLSCU-2 LS2
39QJ1
AB-5A
AB-10J
FLSCU-2 LS3
17QJ2
AB-2A
AB-11H
FLSCU-2 LS4
28QJ2
AB-1B
AB-10K
FLSCU-2 LS5
15QJ1
AB-5B
AB-11J
FLSCU-2 LS6
22QJ
AB-2B
AB-11K
FLSCU-2 LS7
6QJ
AB-3A
AB-12H
FLSCU-2 LS8
NA
Not used
FLSCU-2 LS10
38QJ2
AB-1C
AB-12J
FLSCU-2 LS11
23QJ2
AB-2C
AB-12K
FLSCU-2 LS12
27QJ2
AB-3C
AB-13H
FLSCU-2 LS13
24QJ2
AB-1D
AB-13J
FLSCU-2 LS14
25QJ2
AB-2D
AB-13K
FLSCU-2 LS15
26QJ2
AB-3D
AB-14H
FLSCU-2 T1
29QJ2
AB-4C
AB-15J
FLSCU-2 T2
30QJ2
AB-4D
AB-15K
FLSCU-2 LOGIC 1
9QJ
AB-5C
AB-14J
FLSCU-2 LOGIC 2
9QJ
AB-5D
AB-14
     (a) Repair all the unserviceable wiring and connectors.
     (b) Do the test given in Para. 3.B.
Subtask 28-46-00-810-127-A ** ON A/C NOT FOR ALL
D. Over fuelling to WET the wing full sensors and the surge tank sensors
WARNING: OBEY THE FUEL SAFETY PROCEDURES.
   (1) As necessary, use the applicable SAFETY BARRIERS, specified by the operator's instructions and your local regulations.
   (2) You must obey the fuel safety procedures AMM 28-00-00-910-001 when you work on the fuel system.
   (3) You must obey the safety procedures when fueling the aircraft AMM 12-11-28-650-001 and AMM 12-11-28-650-002.
   (4) Put a container (example, barrel -42 gal) under the applicable NACA vent(s).
   (5) Make sure that a maintenance person stays in the cockpit to turn off the centre tank pumps if:
  • CTR TK PUMP LOW PRESSURE WARNING is generated to prevent dry running of the pump
  • Fuel flows from the outer tank NACA vent(s).
   (6) On the fuel control panel (40VU), set the CTR TK PUMP 1 and 2 P/BSWs to the ON position (pushed in).
   (7) On the fuel control panel (40VU), make sure that the XFEED P/BSW is released out.
   (8) On the Refuel/Defuel control panel (800VU), hold the TEST switch in the HI LVL position.
NOTE: Monitor the fuel transfer from the centre tank to the applicable wing tank until you get the correct fuel quantity.
   (9) Make a record of the FQIC discrete parameters AMM 28-42-00-740-003.
   (10) If the wing full sensors 27QJ1(2) or the wing surge sensors 28QJ1(2) are not indicated in the WET state and fuel flows from the outer tank NACA vent(s):
     (a) On the fuel control panel (40VU), set the CTR TK PUMP 1 and 2 P/BSWs to the OFF position (released out).
     (b) Do the applicable troubleshooting given in the Para. 4. A. (d).
   (11) If the wing full sensors 27QJ1(2) or the wing surge sensors 28QJ1(2) are indicated in the WET state:
     (a) On the fuel control panel (40VU), set the CTR TK PUMP 1 and 2 P/BSWs to the OFF position (released out).
     (b) Do a pressure defuel procedure AMM 28-25-00-650-001.
5. Close-up
Subtask 28-46-00-942-054-A
A. Put the aircraft back to its initial configuration.
   (1) Remove the safety barriers.
   (2) Make sure that the work area is clean and clear of tools and other items.
[Rev.8 from Aug 2018] 2026.04.04 04:29:16 UTC
"WTRUIB" 2025