W DOC AIRBUS | TSM A320F

Fuel Low Level Configuration Warning, Left(Right) Wing Tank

TASK 28-46-00-810-819-A
Fuel Low Level Configuration Warning, Left(Right) Wing Tank

1. Possible Causes
  • FLSCU-1 [7QJ]
  • FLSCU-2 [9QJ]
  • aircraft wiring
  • SDAC-1 [1WV1]
  • SDAC-2 [1WV2]
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
AMM 28-46-00-740-001
Functional (BITE) Test
ASM 284602
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)
AMM 31-55-34-000-001
Removal of the SDAC
AMM 31-55-34-400-001
Installation of the SDAC
3. Fault Confirmation
Subtask 28-46-00-865-050-A
A. Table of the circuit breakers used in this procedure:
PANELDESIGNATIONFINLOCATION
** ON A/C ALL
49VUSDAC/1/SPLY3WVF04
121VUEIS/SDAC/2/SPLY2WVQ06
Subtask 28-46-00-710-050-C ** ON A/C NOT FOR ALL
B. During normal operation of the FLSS/FWC/DMC this is a configuration warning.
If in the inner cell a pair of low level sensors that are AND gated together become dry indicating a fuel level of less than approximately 750kg (1650lb) for more than 30 seconds a low level warning is given.
It is not a warning of a system/LRU failure or malfunction.

However, if the low level warning system is under suspicion:
   (1) On the ECAM CONTROL PANEL push (in) the FUEL P/BSW.
   (2) On the FUEL System Display (Lower ECAM) examine the wing tank FQIs.
   (3) If the wing tank FQI(s) on the related side(s) show less than approximately 750kg (1650lb) when the L(R) or L + R WING TK LO LVL warning is given:
  • no maintenance steps are necessary.
NOTE: Although this procedure has been written for when a permanent LO LVL warning is given, the steps in the procedure are also applicable for when the wing tank FQIs show less than 750kg (1650lb) and the warning is not given.
Subtask 28-46-00-710-050-D ** ON A/C NOT FOR ALL
B. During normal operation of the FLSS/FWC/DMC this is a configuration warning.
If in a wing tank a pair of low level sensors that are AND gated together become dry indicating a fuel level of less than approximately 750kg (1650lb) for more than 30 seconds a low level warning is given.
It is not a warning of a system/LRU failure or malfunction.

However, if the low level warning system is under suspicion:
   (1) On the ECAM CONTROL PANEL push (in) the FUEL P/BSW.
   (2) On the FUEL System Display (Lower ECAM) examine the wing tank FQIs.
   (3) If the wing tank FQI(s) on the related side(s) show less than approximately 750kg (1650lb) when the L(R) or L + R WING TK LO LVL warning is given:
  • no maintenance steps are necessary.
NOTE: Although this procedure has been written for when a permanent LO LVL warning is given, the steps in the procedure are also applicable for when the wing tank FQIs show less than 750kg (1650lb) and the warning is not given.
4. Fault Isolation
Subtask 28-46-00-810-068-C ** ON A/C NOT FOR ALL
A. If the inner cell FQIs on the related side(s) show more than approximately 750kg (1650lb) when the L(R) or L + R WING TK LO LVL warning is given:
   (1) Do the BITE test of the FLSS AMM 28-46-00-740-001.
   (2) If failures are detected examine the FLSS STATUS page for any of the messages that follow:
  • L LO LEVEL SENSOR 16QJ1
  • L LO LEVEL SENSOR 39QJ1
  • R LO LEVEL SENSOR 15QJ2
  • R LO LEVEL SENSOR 39QJ2
  • FLSCU1 7QJ
  • FLSCU2 9QJ.
   (3) If none of the above messages are shown:
  • go to step (5).
   (4) If one or more of the messages identified in Para 4.A.(2) are shown:
  • trouble shoot the LRU(s) before you start more steps.
   (5) On the MCDU set to:
     (a) CFDS.
     (b) SYSTEM REPORT/TEST.
     (c) FUEL.
     (d) INPUT PARAMETER VALUES page 3, the FQIS DISCRETE INPUTS.
   (6) Examine the bit positions as follows (a 1 = wet):
     (a) For the left wing:
  • P3 (16QJ1-LS1/FLSCU1)
  • L5 (39QJ1-LS2/FLSCU2).
     (b) For the right wing:
  • M7 (15QJ2-LS1/FLSCU2)
  • P6 (39QJ2-LS2/FLSCU1).
   (7) If any of the above bit positions in 4.A.(6)(a) and 4.A.(6)(b):
     (a) Show a 0, (when the sensors are wet):
  • do the applicable troubleshooting procedure of the related LRU.
   (8) If all above bit positions show a 1, (the sensors are wet), and the fault continues:
     (a) Remove both FLSCUs from the rack AMM 28-46-34-000-001.
     (b) Apply power to the system/aircraft.
   (9) If the Fuel Low Level Warning is:
     (a) Not given:
       1 Install one FLSCU AMM 28-46-34-400-001 at a time and then apply power to the system/aircraft:
       2 Replace the FLSCU-1 [7QJ] or FLSCU-2 [9QJ] , AMM 28-46-34-000-001 and AMM 28-46-34-400-001 that causes the Low Level Warning to be given.
     (b) Given:
       1 Do a wiring check ASM 284602 of the aircraft wiring :
  • between the FLSCU-1 rack connector AA pin 10A and the SDAC 1 connector AD pin 13K
  • between the FLSCU-1 rack connector AA pin 10A and the SDAC 1 connector AD pin 14K
  • between the FLSCU-1 rack connector AA pin 10A and the SDAC 2 connector AD pin 13K
  • between the FLSCU-1 rack connector AA pin 10A and the SDAC 2 connector AD pin 14K
  • between the FLSCU-2 rack connector AA pin 10A and the SDAC 1 connector AA pin 13D
  • between the FLSCU-2 rack connector AA pin 10A and the SDAC 1 connector AA pin 14D
  • between the FLSCU-2 rack connector AA pin 10A and the SDAC 2 connector AA pin 13D
  • between the FLSCU-2 rack connector AA pin 10A and the SDAC 2 connector AA pin 14D
  • between the FLSCU-1 rack connector AA pin 4A and the FLSCU-2 rack connector AA pin 9A
  • between the FLSCU-1 rack connector AA pin 9A and the FLSCU-2 rack connector AA pin 4A.
   (10) Repair all the unserviceable wiring and connectors.
   (11) If the fault continues:
  • open the C/Bs 3WV (SDAC1) and 2WV (SDAC2) in turn:
   (12) If the fault is displayed on one powered/active SDAC:
  • swap SDACs to confirm the faulty LRU.
   (13) Check/replace the SDAC-1 [1WV1] or SDAC-2 [1WV2] , AMM 31-55-34-000-001 and AMM 31-55-34-400-001, that cause(s) the false low level warning to be given.
NOTE: When AIDS is installed in the aircraft, the AIDS PARA LABEL CALL-UP Menu option can be used to identify which SDAC is giving a false warning as shown in the table below.
---------------------------------------------------------------------------
! PARA LABEL CALL-UP ! !
!---------------------------------! SIGNAL DISCRIPTION !
! EQ ! SYS ! LAB ! SDI ! DATABITS ! !
!----!-----!-----!-----!----------!-----------------------------------------!
! 29 ! 1 ! 004 ! 01 ! 20 ! L WING TK LO LEVEL CHAN A FROM SDAC 1 !
! 29 ! 1 ! 004 ! 01 ! 21 ! L WING TK LO LEVEL CHAN B FROM SDAC 1 !
! 29 ! 1 ! 004 ! 10 ! 21 ! R WING TK LO LEVEL CHAN A FROM SDAC 1 !
! 29 ! 1 ! 004 ! 10 ! 20 ! R WING TK LO LEVEL CHAN B FROM SDAC 1 !
! 29 ! 2 ! 004 ! 01 ! 20 ! L WING TK LO LEVEL CHAN A FROM SDAC 2 !
! 29 ! 2 ! 004 ! 01 ! 21 ! L WING TK LO LEVEL CHAN B FROM SDAC 2 !
! 29 ! 2 ! 004 ! 10 ! 21 ! R WING TK LO LEVEL CHAN A FROM SDAC 2 !
! 29 ! 2 ! 004 ! 10 ! 20 ! R WING TK LO LEVEL CHAN B FROM SDAC 2 !
---------------------------------------------------------------------------

Subtask 28-46-00-810-068-D ** ON A/C NOT FOR ALL
A. If the wing tank FQIs on the related side(s) show more than approximately 750kg (1650lb) when the L(R) or L + R WING TK LO LVL warning is given:
   (1) Do the BITE test of the FLSS AMM 28-46-00-740-001.
   (2) If failures are detected examine the FLSS STATUS page for any of the messages that follow:
  • L(R) LO LEVEL SENSOR 16QJ1(2)
  • L(R) LO LEVEL SENSOR 39QJ1(2)
  • FLSCU1 7QJ
  • FLSCU2 9QJ.
   (3) If none of the above messages are shown:
  • go to step (5).
   (4) If one or more of the messages identified in Para 4.A.(2) are shown:
  • trouble shoot the LRU(s) before you start more steps.
   (5) On the MCDU set to:
     (a) CFDS.
     (b) SYSTEM REPORT/TEST.
     (c) FUEL.
     (d) INPUT PARAMETER VALUES page 3, the FQIS DISCRETE INPUTS.
   (6) Examine the bit positions as follows (a 1 = wet):
     (a) For the left wing:
  • A3 (16QJ1-LS1/FLSCU1)
  • B4 (39QJ1-LS2/FLSCU2).
     (b) For the right wing:
  • A4 (16QJ2-LS1/FLSCU2)
  • B3 (39QJ2-LS2/FLSCU1).
   (7) If any of the above bit positions in 4.A.(6)(a) and 4.A.(6)(b):
     (a) Show a 0, (when the sensors are wet):
  • do the applicable troubleshooting procedure of the related LRU.
   (8) If all above bit positions show a 1, (the sensors are wet), and the fault continues:
     (a) Remove both FLSCUs from the rack AMM 28-46-34-000-001.
     (b) Apply power to the system/aircraft.
   (9) If the Fuel Low Level Warning is:
     (a) Not given:
       1 Install one FLSCU AMM 28-46-34-400-001 at a time and then apply power to the system/aircraft:
       2 Replace the FLSCU-1 [7QJ] or FLSCU-2 [9QJ] , AMM 28-46-34-000-001 and AMM 28-46-34-400-001 that causes the Low Level Warning to be given.
     (b) Given:
       1 Do a wiring check ASM 284602 of the aircraft wiring :
  • between the FLSCU-1 rack connector AA pin 10A and the SDAC 1 connector AD pin 13K
  • between the FLSCU-1 rack connector AA pin 10A and the SDAC 1 connector AD pin 14K
  • between the FLSCU-1 rack connector AA pin 10A and the SDAC 2 connector AD pin 13K
  • between the FLSCU-1 rack connector AA pin 10A and the SDAC 2 connector AD pin 14K
  • between the FLSCU-2 rack connector AA pin 10A and the SDAC 1 connector AA pin 13D
  • between the FLSCU-2 rack connector AA pin 10A and the SDAC 1 connector AA pin 14D
  • between the FLSCU-2 rack connector AA pin 10A and the SDAC 2 connector AA pin 13D
  • between the FLSCU-2 rack connector AA pin 10A and the SDAC 2 connector AA pin 14D
  • between the FLSCU-1 rack connector AA pin 4A and the FLSCU-2 rack connector AA pin 9A
  • between the FLSCU-1 rack connector AA pin 9A and the FLSCU-2 rack connector AA pin 4A.
   (10) Repair all the unserviceable wiring and connectors.
   (11) If the fault continues:
  • open the C/Bs 3WV (SDAC1) and 2WV (SDAC2) in turn:
   (12) If the fault is displayed on one powered/active SDAC:
  • swap SDACs to confirm the faulty LRU.
   (13) Check/replace the SDAC-1 [1WV1] or SDAC-2 [1WV2] , AMM 31-55-34-000-001 and AMM 31-55-34-400-001, that cause(s) the false low level warning to be given.
NOTE: When AIDS is installed in the aircraft, the AIDS PARA LABEL CALL-UP Menu option can be used to identify which SDAC is giving a false warning as shown in the table below.
---------------------------------------------------------------------------
! PARA LABEL CALL-UP ! SIGNAL DISCRIPTION !
!---------------------------------! (LO LEVEL CHANs identified below !
! EQ ! SYS ! LAB ! SDI ! DATABITS ! refer to 750kg/1650lb) !
!----!-----!-----!-----!----------!-----------------------------------------!
! 29 ! 1 ! 004 ! 01 ! 20 ! L WING TK LO LEVEL CHAN A FROM SDAC 1 !
! 29 ! 1 ! 004 ! 01 ! 21 ! L WING TK LO LEVEL CHAN B FROM SDAC 1 !
! 29 ! 1 ! 004 ! 10 ! 21 ! R WING TK LO LEVEL CHAN A FROM SDAC 1 !
! 29 ! 1 ! 004 ! 10 ! 20 ! R WING TK LO LEVEL CHAN B FROM SDAC 1 !
! 29 ! 2 ! 004 ! 01 ! 20 ! L WING TK LO LEVEL CHAN A FROM SDAC 2 !
! 29 ! 2 ! 004 ! 01 ! 21 ! L WING TK LO LEVEL CHAN B FROM SDAC 2 !
! 29 ! 2 ! 004 ! 10 ! 21 ! R WING TK LO LEVEL CHAN A FROM SDAC 2 !
! 29 ! 2 ! 004 ! 10 ! 20 ! R WING TK LO LEVEL CHAN B FROM SDAC 2 !
---------------------------------------------------------------------------

[Rev.8 from Aug 2018] 2026.04.04 04:29:17 UTC
"WTRUIB" 2025