Fault Message:

HYD PUMP 3B FAIL

Fault Code:

0000H3BF

Associated CAS:

HYD PUMP 3B FAIL
(Advisory)

Data Acquisition Units (DAU) 4 is receiving an input that the Hydraulic Pressure Switch 3B is less than 1800 psi (low) with Hydraulic Pump Switch 3B selected to AUTO or ON.

NOTE: AC Motor Pump (ACMP) Pressure Switches close at 2400 psi (high) as pressure rises and opens at 1800 psi (low) as pressure decreases.

• AC Power Center (ACPC) Secondary Logic Card (SLC) 1
• AC Motor Pump (ACMP) 3B (B54)
• AC Power Center (ACPC) Relay (K14)
• AC Motor Pump (ACPC) Pressure Switch 3B (S40)
• AC Power Center (ACPC) (A54)
• Data Acquisition Units (DAU) 4 (A31)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. Ensure 3 Hydraulic System is properly serviced.
2. Operate Hydraulic Pump 3B and note Hydraulic System 3 pressure.

   1. If pump operates and pressure in below 2400 psi, replace ACMP 3B and do close out.
   2. If pump does not operate, go to step 4.
   3. If pump operates and pressure is above 2400 psi, continue with next step.

3. Swap Hydraulic Pressure Switch 3B and 3A.

   1. If system checks are good, replace Hydraulic Pressure Switch 3B and do close out.
   2. If fault remains, go to step 8.

4. Perform voltage check at ACMP 3B. Check for 115 VAC at connector B54P1 as follows:

   From	To	Expected Result	Result
   B54P1-A	B54P1-E	115 VAC
   B54P1-B	B54P1-E	115 VAC
   B54P1-C	B54P1-E	115 VAC

   1. If voltage is present, replace ACMP 3B and do close out.
   2. If voltage is not present, continue with next step.

5. Swap ACPC SLC AC-1 with SLC AC-3.

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

6. Swap K14 relay with K20 relay in ACPC.

   1. If system checks are good, replace K14 relay and do close out.
   2. If fault remains, continue with next step.

7. Perform wiring checks between ACMP 3B, ACPC Relay K14, Hydraulic Pressure Switch 3B and DAU 4.

   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.

8. Swap DAU 4 with DAU 2.

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

9. Accomplish check of EMI filter as shown below.
10. Remove ACPC Secondary Logic Card 1 (SLC4).
11. Measure the EMI Filter continuity from connector P110 pin 22 to aircraft structure.

    1. If reading is ground, replace the ACPC and do close out.
    2. If reading is open, continue with next step.

12. Measure for open circuit between SLC 1 as follows:

    From	To	Result
    P110-22	P110-25
    P110-22	P110-28
    P110-22	P110-31

    1. If reading are closed, do close out.
    2. If reading are open, continue with next step.

13. Replace ACPC.
14. Do close out.