Fault Message:

APU NO ACCELERATION

Fault Code:

4960132APU

Associated CAS:

APU SHUTDOWN
(Advisory)

After ignition occurs, the acceleration rate is less than 0.05%/sec for 15 seconds or more. In this condition, the Full Authority Digital Engine (Electronic) Control (FADEC) will cause an Auxiliary Power Unit (APU) shutdown.

The Correlated Fight Deck Effect (FDE) is the Engine Indication and Crew Alerting System (EICAS) advisory message APU SHUTDOWN.

• Inlet Pressure Sensor (MT1)
• Inlet Temperature Sensor (MT3)
• Exhaust-Gas Temperature (EGT) sensor (TC1)
• Fuel-Control Torque Motor
• Fuel Solenoid Valve (V2)
• Fuel Flow-Divider Valve
• Load Control Valve (MPE1)
• Surge Valve (MPE2)
• Starter Motor (B55)
• Fuel Control Unit (FCU) (A3)
• De-Prime Valve (V1)
• Auxiliary Power Unit (APU)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. Check for fault message as follow:

   • FADEC CONTROLLER
   • FCU [TRQ MOT SINGLE COIL OPEN CKT]
   • GROUND SHORT- INLET TEMP SENSOR/WRG
   • INLET PRESSURE SENSOR [SIGNAL OUT HI]
   • INLET PRESSURE SENSOR [SIGNAL OUT LO]
   • INLET TEMP SENSOR [SIGNAL OUT HIGH]
   • INLET TEMP SENSOR [SIGNAL OUT LOW]
   • LOAD CONT VLV [LCV POSITION VS CMD]
   • OPEN CIRCUIT - SURGE VALVE/WIRING
   • OPEN CKT - DE-PRIME VALVE/WIRING
   • OPEN CKT - EGT SENSOR/CKT 1 WIRING
   • OPEN CKT - EGT SENSOR/CKT 2 WIRING
   • OPEN CKT - FCU/FCU TORQUE MOTOR WRG
   • OPEN CKT-FCU [SHUT OFF SOL]/WIRING
   • OPEN CKT-FUEL SOLENOID VALVE/WIRING
   • OPEN CKT-INLET PRESS SENSOR/EXC WRG
   • OPEN CKT- INLET PRESS SNSR/WRG
   • OPEN CKT - INLET TEMP SENSOR/WIRING
   • OPEN CKT- LCV/LCV TORQUE MOT WIRING
   • POS VS CMD-INLET DOOR LIN ACTR/XDCR
   • SHORT - EGT SENSOR/CIRCUIT 1 WIRING
   • SHORT - EGT SENSOR/CIRCUIT 2 WIRING
   • SHORT - FCU/FCU TORQUE MOTOR WRG
   • SHORT - FUEL SOLENOID VALVE/WIRING
   • SHORT - INLET PRESS SENSOR/EXC WRG
   • SHORT- INLET PRESS SNSR/POS SIG WRG
   • SHORT CIRCUIT - SURGE VALVE/WIRING
   • SHORT CKT - DE-PRIME VALVE/WIRING
   • SHORT CKT-FCU [SHUT OFF SOL]/WIRING
   • SHORT CKT-LCV/LCV TORQUE MOT WIRING
   • SIG SHORT- INLET TEMP SENSOR/WRG

     1. If any of the fault message message is active, throubleshoot them first and continue with next step.
     2. If none of the active fault messages above show, continue with next step.

2. 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 bare wiring, kinks, worn areas or other damage, continue with next step.

3. Check for fault message APU SHUTDOWN (Advisory) shows on the EICAS primary display.

   1. If fault messages is not active, do close out.
   2. If fault message message is active, continue with next step.

4. Examine the inlet door for blockage.

   1. If the inlet door has blockage, remove blockage and do close out.
   2. If the inlet door has no blockage, continue with next step.

5. Check for fault message APU SHUTDOWN (Advisory) still shows on the EICAS primary display.

   1. If fault messages is not active, do close out.
   2. If fault message message is active, continue with next step.

6. Open the APU inlet door, examine the inlet-duct forward section for blockage using a optic fiber borescope (borescope) through the inlet door.

   1. If the inlet-duct forward section has blockage, remove the blockage and do close out.
   2. If the inlet-duct forward section has no blockage, continue with next step.

7. Check for fault message APU SHUTDOWN (Advisory) still shows on the EICAS primary display.

   1. If fault messages is not active, do close out.
   2. If fault message message is active, replace starter motor and continue with next step.

8. Check for fault message APU SHUTDOWN (Advisory) still shows on the EICAS primary display.

   1. If fault messages is not active, do close out.
   2. If fault message message is active, replace fuel control unit and continue with next step.

9. Check for fault message APU SHUTDOWN (Advisory) still shows on the EICAS primary display.

   1. If fault messages is not active, do close out.
   2. If fault message message is active, replace the fuel solenoid valve and continue with next step.

10. Check for fault message APU SHUTDOWN (Advisory) still shows on the EICAS primary display.

    1. If fault messages is not active, do close out.
    2. If fault message message is active, replace the fuel flow-divider valve and continue with next step.

11. Check for fault message APU SHUTDOWN (Advisory) still shows on the EICAS primary display.

    1. If fault messages is not active, do close out.
    2. If fault message message is active, replace the de-prime valve and continue with next step.

12. Check for fault message APU SHUTDOWN (Advisory) still shows on the EICAS primary display.

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

13. Replace APU.
14. Do Close out.