Fault Message:

APU INLET DOOR FAILURE TO CLOSE

Fault Code:

4960304APU

Associated CAS:

APU DOOR FAIL
(Caution)

Full-Authority Digital Engine-Controller (FADEC) has detected that the Auxiliary Power Unit (APU) Air Inlet Door is not in the commanded position.

• APU Starter-Contactor Assembly (ASCA) (A48)
• Auxiliary Power Unit (APU) Full-Authority Digital Engine-Controller (FADEC) (A108)
• Inlet Door Position Indicator (MT5)
• Door Actuator (A199)
• Associated Wiring

1. Check for FADEC CONTROLLER fault message on the CAIMS PMAT.

   1. If message is not shown, go to step 3.
   2. If message is shown, continue with next step.

2. Replace FADEC.

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

3. Visually check door position and inspect air inlet door for blockage or damage. Replace or remove blockage as required.

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

4. Re-rack FADEC.

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

5. Confirm that door is closed, perform wiring checks between FADEC and inlet position rotary transducer connector (P804).

   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.

6. Replace door position rotary transducer.

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

7. Disconnect A199P1 connector from linear actuator (A199). Examine receptacle for contamination and damage. Clean/replace as required.

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

8. Perform continuity checks between each pin and the grounded shell of A199 receptacle. Check for resistance of more than one mega ohms for each wire. Repair as required.

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

9. Swap linear actuator.

   1. If system checks are good, go to step 16.
   2. If fault remains, continue with next step.

10. Perform continuity checks between pins of connectors P803 and A199P1. Check for resistance of more than one mega ohms for each wire. Repair as required.

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

11. Perform continuity checks between each pin and the grounded shell of A199P1. Check for resistance of more than one mega ohms for each wire. Repair as required.

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

12. Disconnect connector J803 and A48P1. Perform a continuity check between connector J803 and A48P1. The resistance should measure as follows:

    From	To	Expected Result	Result
    J803-L	A48P1-e	>1 megohm

    1. If the resistance is not as mentioned above, replace defective wiring as required and do close out.
    2. If the resistance is as mentioned above, continue with next step.

13. Remove FADEC. Perform a continuity check between pins of connector J803 and A108BP1. Check for resistance of less than 3 ohms. Repair as required.

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

14. Perform continuity checks between each pin on the shell of connector J803. Check for resistance of more than one mega ohms for each wire. Repair as required.

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

15. Replace inlet door actuator.

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

16. Replace Linear Actuator.
17. Do close out.