Fault Message:

ACPC EHP 3A CONTACTOR-K24 FAILED

Fault Code:

2451353ACP

Associated CAS:

ELEC SYS FAULT
(Advisory)

During the power on sequence, the Secondary Logic Card (SLC) will verify that the Electric Hydraulic Pump (EHP) Contactor is open and the EHP current sensing circuit is functional. During the continuous monitoring, the SLC will verify that the EHP Contactor status against its trip status and commanded state.

• AC Power Center (ACPC) (A54)
• AC Power Center (ACPC) Contactor (K24)
• Secondary Logic Card (SLC) 4
• Hydraulic Control Panel (AP4)
• Electric Hydraulic Pump (EHP) 3A (B53)
• 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 4 with SLC 3.

   1. If system checks are good, replace SLC 4 and do close out.
   2. If fault remains, continue with next step.

2. Get access to the ACPC contactor K24.
3. Disconnect contactor K24 connector P406.
4. Turn the BATT MSTR SW to ON.
5. Check for 28 VDC as follows:

   From	To	Result
   P406-1	Ground

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

6. Verify voltage from the TB402-3. 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 4.
9. Perform a continuity check with the connections as follows:

   From	To	Result
   P406-22	Ground
   P406-3	Ground
   P410-31	Ground
   P410-28	Ground
   P410-25	Ground
   P410-22	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 3A 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 as follows:

    From	To	Resuly
    P411C-23	Ground

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

12. Disconnect connector A54P2 and perform continuity check as follows:

    From	To	Result
    P411C-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 as follows:

    From	To	Result
    A54P2-P	AP4P1-7
    AP4P1-13	Ground
    AP4P1-13	HYD Panel

    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 as follows:

    From	To	Result
    P406-2	Ground

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

15. Verify TB402-7. 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
    P406-22	P411C-11
    P406-3	P411C-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 3A to ON.
18. Perform a continuity check as follows:

    From	To	Result
    P411C-23	Ground

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

19. Disconnect connector A54P2 and perform continuity check as follows:

    From	To	Result
    P411C-23	A54J2-P

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

20. Perform a continuity check as follows:

    From	To	Result
    A54P2-P	AP4P1-7
    AP4P1-13	Ground
    AP4P1-13	HYD Panel

    1. If there is continuity, do close out.
    2. If there is no continuity, continue with next step.

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

    From	To	Result
    P410-22	P410-31
    P410-22	P410-28
    P410-22	P410-25

    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 B53P1. Apply AC power and select HYD Pump 3A to ON.

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

23. Replace contactor K24.

    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 3A system.
26. Do close out.