This caution message shows when the inlet door is not in the correct position or the Inlet Door Rotary Transducer is defective. An 'APU DOOR FAIL' amber CAS message will also be posted.

• Inlet-Door Rotary Transducer (RVDT) (MT5)
• Auxiliary Power Unit (APU) Full-Authority Digital Engine-Controller (FADEC) (A108)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

If CAS message is not active, verify stored faults on CAIMS.

1. Inspect the wiring and connectors to the inlet-door rotary transducer for any damage.

   1. If damages are found, repair as required and do close out.
   2. If damages are not found, continue with next step.

2. Re-rack FADEC and verify connector A108AP1-A8 and A108AP1-B8 for damage or FOD.

   1. If damages are found, repair as required and do close out.
   2. If damages are not found, continue with next step.

3. Inspect the transducer for condition and perform continuity check on transducer (P804) as follows:

   From	To	Expected Result	Result
   P804-4	P804-6	<1000 ohms

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

4. Perform continuity check between transducer (P804) and grounded shell as follows:

   From	To	Expected Result	Result
   P804-4	Ground	>1 megaohm
   P804-6	Ground	>1 megaohm

   1. If the resistance check is not as mentioned above, replace defective inlet door rotary transducer and do close out.
   2. If the resistance check is as mentioned above, continue with next step.

5. Perform wiring checks between APU FADEC connector (A108AP1) and the transducer connector (J804 to J803 should be less than 1 Ohm, J803 to APU FADEC tray A108BP1 should be less than 3 Ohms).

   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 the APU FADEC.
7. Do close out.