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Center Tank Pump Auto Control (Two Minute Run Period At Main Engine Start) Failure

TASK 28-21-00-810-841-A
Center Tank Pump Auto Control (Two Minute Run Period At Main Engine Start) Failure

WARNING: OBEY THE FUEL SAFETY PROCEDURES.
1. Possible Causes
  • aircraft wiring between the RELAY 51QA(52QA), pin X1 and the P/BSW-FUEL CTR TK/PUMP 1(2) 33QA(34QA), terminal B1
  • aircraft wiring between the EIU-1 (1KS1) rack connector AB, pin 1C and the RELAY 51QA(52QA), base pin 1C
  • aircraft wiring between the EIU-2 (1KS2) rack connector AB, pin 1C and the terminal block 1853VT, terminal 20U
  • aircraft wiring between the ECB (59KD) rack connector AB, pin 5E and the terminal block 1853VT, terminal 20T
  • RELAY-CTR TK PUMPS 1 CTL [51QA]
  • RELAY-CTR TK PUMPS 2 CTL [52QA]
  • RELAY 51QA(52QA) base
  • EIU-1 [1KS1]
  • EIU-2 [1KS2]
2. Job Set-up Information
 A. Fixtures, Tools, Test and Support Equipment
REFERENCE
QTY
DESIGNATION
No specific
AR
MULTIMETER - STANDARD
 B. Referenced Information
REFERENCE
DESIGNATION
TSM TASK 28-21-00-810-813-A
Fuel Pumps - Center Tank Fuel Pump No. 1 (Left Side) 37QA System Malfunction
TSM TASK 28-21-00-810-814-A
Fuel Pumps - Center Tank Fuel Pump No. 2 (Right Side) 38QA System Malfunction
TSM TASK 28-21-00-810-817-A
Fuel Pumps - Center Tank Fuel Pump No. 1 (Left Side) Contactor Control Failure (Manual Control)
TSM TASK 28-21-00-810-818-A
Fuel Pumps - Center Tank Fuel Pump No. 2 (Right Side) Contactor Control Failure (Manual Control)
AMM 28-21-00-710-005
Operational Check to Ensure that Both Center Tank Pumps Feed for 2 Minutes After Engine Start
ASM 282103
ASM 282104
AWM 282105
AWM 282106
AWM 282107
AWM 496103
AWM 732505
AWM 732506
AMM 73-25-34-000-040
Removal of the Engine Interface Unit (EIU)
AMM 73-25-34-400-040
Installation of the Engine Interface Unit (EIU)
3. Fault Confirmation
Subtask 28-21-00-710-087-B ** ON A/C NOT FOR ALL
A. Do the Operational Test of the Main Fuel Pump System to Ensure Both Center Tank Pumps Feed for 2 Minutes After an Engine Start AMM 28-21-00-710-005.
   (1) If the center tank pumps operate as specified, further maintenance steps are not necessary.
   (2) If the center tank pumps do not operate as specified, go to Para. 4.
4. Fault Isolation
Subtask 28-21-00-810-087-B ** ON A/C NOT FOR ALL
A. If the center tank fuel pumps fail to operate in the manual mode of operation, do the applicable task that follows:
   (1) If the center tank fuel pumps fail in the two (2) minute automatic water scavenge function:
  • remove and retain the RELAY 51QA(52QA).
   (2) Examine the RELAY 51QA(52QA) and the relay base for any signs of damage or burning of the pins.
   (3) Make sure the P/BSW-FUEL/CTR TK/PUMP 1(2) 33QA(34QA) is pushed in (set to on).
   (4) With a MULTIMETER - STANDARD, do a test to make sure that 28VDC is available at the RELAY 51QA(52QA) base pin X1.
NOTE: Each Time Delay Opening (TDO) relays power supply input to pin X1 comes from its related center tank fuel pump P/BSW.
   (5) If 28VDC was not available at RELAY 51QA(52QA) base pin X1 as in step (4):
     (a) Do a check of the aircraft wiring between the RELAY 51QA(52QA), pin X1 and the P/BSW-FUEL CTR TK/PUMP 1(2) 33QA(34QA), terminal B1 ASM 282103 and ASM 282104.
     (b) Repair all the unserviceable wiring and connectors.
     (c) Do the test given in Para. 3.A.
   (6) At the panel 85VU:
   (7) Apply 28VDC to the EIU-1 (1KS1) rack connector AB, pin 1C.
   (8) With a multimeter, do a test to make sure that 28VDC is available at the RELAY 51QA(52QA) base pin C1.
NOTE: Each TDO relays control 28VDC input to pin C1 comes from either EIU-1 or EIU-2 or both and signals a Main Engine Start (MES).
   (9) Install the EIU-1 (1KS1) AMM 73-25-34-400-040.
   (10) Remove the EIU-2 (1KS2) AMM 73-25-34-000-040.
   (11) Apply 28VDC to the EIU-2 (1KS2) rack connector AB, pin 1C.
   (12) With a multimeter, do a test to make sure that 28VDC is available at the RELAY 51QA(52QA) base pin C1.
   (13) If 28VDC (simulated MES) was not available at RELAY 51QA(52QA) base pin C1 (step (8) and/or step (12)):
     (a) Do a check of the:
  • aircraft wiring between the EIU-1 (1KS1) rack connector AB, pin 1C and the RELAY 51QA(52QA), base pin 1C AWM 282105 AWM 282106 AWM 282107 and AWM 732505
  • aircraft wiring between the EIU-2 (1KS2) rack connector AB, pin 1C and the terminal block 1853VT, terminal 20U AWM 732506
  • aircraft wiring between the ECB (59KD) rack connector AB, pin 5E and the terminal block 1853VT, terminal 20T AWM 496103.
     (b) Repair all the unserviceable wiring and connectors.
     (c) Do the test given in Para. 3.A.
   (14) If the 28VDC is as specified in steps (4), (8) and (12) and/or if the relay(s) show(s) signs of damage or burning in step (2):
  • replace the RELAY-CTR TK PUMPS 1 CTL [51QA] ( RELAY-CTR TK PUMPS 2 CTL [52QA] ).
   (15) If the RELAY 51QA(52QA) base shows any signs of damage or burning in step (2):
  • replace the RELAY 51QA(52QA) base.
   (16) Do the test given in Para. 3.A.
   (17) If the fault continues during a main engine start:
  • trouble-shoot the EIU-1 [1KS1] ( EIU-2 [1KS2] ) and interfaces (Ref. Chap. 73-25-00).
[Rev.8 from Aug 2018] 2026.04.04 04:39:35 UTC
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