Fault Message:

LH AFT AC BOOST PUMP ELECT PWR/WRG

Fault Code:

2844606PK

Associated CAS:

L PRI FUEL PUMPS
(Caution)

L PRI FUEL PUMP
(Advisory)

Fuel Management Quantity and Gauging Computer (FMQGC) senses that the Left Wing Aft AC Boost-Pump is not able to go off or on as commanded due to an Electrical Load Management System (LMS) failure.

• AC Power Center (ACPC)/Solid-State Power Controller (SSPC) 1 (A2)
• AC Power Center (ACPC) Secondary Logic Card (A7)
• Left Aft AC Boost Pump Cartridge (B7)
• Fuel Management Quantity and Gauging Computer (FMQGC) (A47)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Article/Infoservice/Newsletter: None

NOTE: If both of the CAIMS messages L AFT AC BOOST PUMP/WRG FAULT and L AFT AC BOOST PUMP LMS/WRG FAULT are displayed, troubleshoot with L AFT AC BOOST PUMP/WRG FAULT page first.

1. Using the PMAT, access CAIMS, SYSTEM DIAG. Select ATA 24, ACPC A (B), LOAD STATUS LABEL 002, LOAD 1 (L AFT PRI PUMP, Phase A) page. Set the left ENGINE RUN switch to ON and the L PRI PUMPS switch/light to ON (Pushed out). Make sure the result that follows are met:

   Reference	Status
   LOGIC EQUATION STATE (L TRANSFER REQUEST)	ON
   VIRTUAL CIRCUIT BREAKER (SSPC CIRCUIT BREAKER)	IN
   VIRTUAL SWITCH (SSPC SW)	ON
   LOCK STATE	UNLOCKED
   VOLTAGE STATUS	PRESENT
   CURRENT STATUS	FLOWING
   TRIP STATUS (CIRCUIT BREAKER)	NOT TRIP
   FAIL STATUS (SSPC)	NOT FAILED

   1. If all of the above status are met, go to step 8.
   2. If one or more of the above status is not met, go to step 3.
   NOTE: Repeat this step by selecting LABEL 002 Load 2 (L AFT PRI PUMP, Phase B) and LABEL 003 Load 1 (L AFT PRI PUMP, Phase C).

2. An alternative way of monitoring the result is to select ACPC IN via EMS CDU1 or CDU2 Signboard Menu:

   	Left column	Center column
   Label 002	29 28 27 26 25 24 23 22 1 1 1 1 1 1	21 20 19 18 17 16 15 14 1 1 1 1 1 1
   Reference	L AFT PRIM PUMP Phase B	L AFT PRIM PUMP Phase A
   Label 003	29 28 27 26 25 24 23 22 X X X X X X X X	21 20 19 18 17 16 15 14 1 1 1 1 1 1
   Reference		L AFT PRIM PUMP Phase C

   • Built-In Test (BIT) 14 or 22:LOGIC EQUATION STATE (L TRANSFER REQUEST)
   • Built-In Test (BIT) 15 or 23:VIRTUAL CIRCUIT BREAKER (SSPC CIRCUIT BREAKER)
   • Built-In Test (BIT) 16 or 24:VIRTUAL SWITCH (SSPC SW)
   • Built-In Test (BIT) 17 or 25:LOCK STATE
   • Built-In Test (BIT) 18 or 26:VOLTAGE STATUS
   • Built-In Test (BIT) 19 or 27:CURRENT STATUS
   • Built-In Test (BIT) 20 or 28:TRIP STATUS (CIRCUIT BREAKER)
   • Built-In Test (BIT) 21 or 29:FAIL STATUS (SSPC)

   1. If the above status are met, go to step 8.
   2. If one or more of the above status is not met, continue with next step.

3. Perform wiring check (short to ground=fail) between the ACPC (A54P5) and left wing aft AC boost-pump (B7P1).

   1. If wiring checks are not good, repair defective wiring as required and do close out.
   2. If wiring checks are good, continue with next step.

4. Perform a ground check at left wing aft AC boost-pump (B7J1). Repair as required.

   1. If ground is not present, go to step 6.
   2. If ground is present, continue with next step.

5. Swap the left wing AC boost-pump. Is the fault still present?

   1. If NO, replace left wing AC boost-pump and do close out.
   2. If YES, continue with next step.

6. Swap the ACPC/SSPC 1 (A2). Is the fault still present?

   1. If NO, replace ACPC/SSPC 1 (A2) and do close out.
   2. If YES, continue with next step.

7. Swap the ACPC Secondary Logic Card (SLC) (A7). Is the fault still present?

   1. If NO, replace ACPC Secondary Logic Card (SLC) (A7) and do close out.
   2. If YES, continue with next step.

8. Remove the FMQGC. Re-install the FMQGC making sure it is fully and properly inserted into place. Is the fault still present?

   1. If NO, do close out.
   2. If YES, continue with next step.

9. Replace FMQGC.
10. Do close out.