Fault Message:

ACPC EHP 1B CONTACTOR-K20 FAILED

Fault Code:

2451344ACP

Associated CAS:

ELEC SYS FAULT
(Advisory)

During the power on sequence, Secondary Logic Card (SLC) will verify that Electric Hydraulic Pump (EHP) Contactor is open and EHP current sensing circuit is functional.

During the continuous monitoring, SLC will verify EHP Contactor status against its trip status and commanded state.

• AC Power Center (ACPC) (A54)
• AC Power Center (ACPC) Contactor (K4)
• Secondary Logic Card (SLC) 3
• Hydraulic Panel (AP4)
• Electric Hydraulic Pump (EHP) 1B (B51)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Past experience:

1. Hyd pump failed in flight with switch in auto:

   1. We did the following procedure and no anomalies noted.
   2. We performed a ground run (ground idle and flight idle) and no anomalies noted.
   3. They flushed the hydraulic system and no anomalies noted.
   4. We instrumented the hydraulic system, performed flight test and found abnormal in-rush current from hydraulic pump with N2 around 90%. The issue was related to the back feed from the engine driven hydraulic pump.
   5. They replaced manifold and fixed the issue.

1. Swap SLC 3 with SLC 4.

   1. If system checks are good, replace SLC 3 and do close out.
   2. If fault remains, continue with next step.

2. Get access to the ACPC contactor K20.
3. Disconnect contactor K20 connector P306.
4. Turn the BATT MSTR SW to ON.
5. Check for 28 Volts DC between ACPC to ground as follow:

   From	To	Result
   P306-1	Ground

   1. If there is 28 Volts DC, go to step 7.
   2. If there is no 28 Volts DC, continue with next step.

6. Verify voltage from the TB302-1. Repair as required.

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

7. Turn the BATT MSTR SW to OFF.
8. Remove SLC 3.
9. Perform a continuity check with the connections as follows:

   From	To	Result
   P306-22	Ground
   P306-3	Ground
   P310-23	Ground
   P310-26	Ground
   P310-29	Ground
   P310-32	Ground

   1. If there is continuity, go to step 24.
   2. If there is no continuity, continue with next step.

10. Make sure the Hydraulic Pump 1B is select to OFF.
    CAUTION: To prevent damage to the ACPC motherboard connectors, ensure that the wire jumper pin Outside Diameter (OD)/socket Inside Diameter (ID) does not exceed 0.025 inch.
11. Perform a continuity check between SLC 3 and ground as follows:

    From	To	Result
    P311C-23	Ground

    1. If there is no continuity, go to step 14.
    2. If there is continuity, continue with next step.

12. Disconnect connector A54P3 and perform a continuity check between SLC 3 and ground as follows:

    From	To	Result
    P311C-23	Ground

    1. If there is continuity, go to step 24.
    2. If there is no continuity, continue with next step.

13. Perform a wiring check between ACPC to HYD Panel and HYD panel to ground as follows:

    From	To	Result
    A54P3-N	AP4P1-4
    AP4P1-11	Ground

    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.

14. Perform a continuity check between ACPC and ground as follows:

    From	To	Result
    P306-2	Ground

    1. If there is continuity, go to step 16.
    2. If there is no continuity, continue with next step.

15. Verify voltage from the TB302-3. Repair as required.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

16. Perform a continuity check with the connections as follows:

    From	To	Result
    P306-22	P311C-11
    P306-3	P311C-18

    1. If there is no continuity, go to step 24.
    2. If there is continuity, continue with next step.

17. Select the switch HYD 1B to ON.
18. Perform a continuity check between SLC 3 and ground as follows:

    From	To	Result
    P311C-23	Ground

    1. If there is continuity, go to step 21.
    2. If there is no continuity, continue with next step.

19. Disconnect connector A54P3 and perform a continuity check within ACPC as follows:

    From	To	Result
    P311C-23	A54P3-N

    1. If there is no continuity, go to step 24.
    2. If there is continuity, continue with next step.

20. Perform a continuity check between ACPC to HYD Panel and HYD panel to ground as follows:

    From	To	Result
    A54P3-N	AP4P1-4
    AP4P1-11	Ground

    1. If there is no continuity, repair defective wiring as required and do close out.
    2. If there is continuity, continue with next step.

21. Perform a and record a resistance check with the connections as follow:

    From	To	Record
    P310-23	P310-26
    P310-23	P310-29
    P310-23	P310-32

    1. If the resistance values are not identical, go to step 24.
    2. If the resistance values are identical, continue with next step.

22. Disconnect connector B51P1. Apply AC power and select HYD Pump 1B to ON.

    1. If fault is not present, go to step 25.
    2. If fault is present, continue with next step.

23. Replace contactor K20.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

24. Replace ACPC.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

25. Troubleshoot the hydraulic 1B system.
26. Do close out.