Message Name:

APU INLET TEMPERATURE OUT OF RANGE

The Full-Authority Digital Engine-Controller (FADEC) received incorrect Inlet Temperature Sensor inputs because of the conditions that follow:

• Inlet Temperature Sensor conditioning voltage in the FADEC is out of range low (this shows a possible short to ground in the Inlet Temperature Sensor or the Engine Branched Wiring-Harness)
• Inlet Temperature Sensor conditioning voltage in the FADEC is out of range low and the signal read by the FADEC is out of range low (this shows possible signal wires shorted together in the Inlet Temperature Sensor or the Engine Branched Wiring-Harness)

• Inlet Temperature Sensor (MT3)
• Full-Authority Digital Engine-Controller (FADEC) (A108)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. Examine the engine branched wiring-harness for bare wiring, kinks, worn areas and other damage (WM 49-12).

   1. If there is bare wiring, kinks, worn areas or other damage, replace engine branched wiring-harness and do close out.
   2. If there is no damage, continue with next step.

2. Examine the inlet temperature sensor (MT3) receptacle for contamination and damage.

   1. If there is contamination or damage, go to step 9.
   2. If there is no contamination or damage, continue with next step.

3. Perform a resistance check as follows:

   From	To	Expected Result	Result
   MT3-A	MT3-B	50-250 Ohms

   1. If the resistance value is not as specified, go to step 9.
   2. If the resistance value is as specified, continue with next step.

4. Perform a continuity check as follows:

   From	To	Result
   MT3-A	Ground
   MT3-B	Ground

   1. If there is continuity, go to step 9.
   2. If there is no continuity, continue with next step.

5. Perform wiring checks between APU (P802) and inlet temperature sensor (MT3P1).

   1. If the wiring checks are not good, repair defective wiring as required and do close out.
   2. If the wiring checks are good, continue with next step.

6. Perform a continuity check as follows:

   From	To	Result
   P802-63	Ground
   P802-64	Ground
   MT3P1-A	Ground
   MT3P1-B	Ground

   1. If there is continuity, replace engine branched wiring-harness and do close out.
   2. If there is no continuity, continue with next step.

7. Perform a continuity check as follows:

   From	To	Result
   J802-63	Ground
   J802-64	Ground
   A108BP1-H5	Ground
   A108BP1-J5	Ground

   1. If there is continuity, replace the engine branched wiring-harness and do close out.
   2. If there is no continuity, continue with next step.

8. Perform the wiring checks between AC wiring harness (J802) and FADEC (A108BP1).

   1. If the wiring checks are not good, repair defective wiring as required and do close out.
   2. If the wiring checks are good, replace FADEC (A108) and do close out.

9. Replace the Inlet Temperature Sensor (MT3).
10. Do close out.