Fault Message:

APU SLOW START CONDITION 2

Fault Code:

4960141APU

Associated CAS:

APU SHUTDOWN
(Advisory)

This CAIMS message is shown when the Auxiliary Power Unit (APU), after 30 seconds, increases to the speed that the Starter Motor is disengaged but does not increase to the ready-to-load speed. In this condition, the Full-Authority Digital Engine-Controller (FADEC) will cause an APU shutdown.

• Auxiliary Power Unit (APU) Inlet Pressure Sensor (MT1)
• Inlet Temperature Sensor (MT3)
• Exhaust Gas Temperature Sensor (TC1)
• Fuel Control Torque Motor
• Fuel Solenoid Valve (V2)
• Fuel Flow Divider Valve
• Load Control Valve (MPE1)
• Surge Valve (MPE2)
• Inlet Door
• Inlet Duct
• 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. On the CAIMS PMAT, get access to the active faults:
   Select the CAIMS message:4960118APU - FADEC CONTROLLER4960149APU - OPEN CKT - EGT SENSOR/CKT 1 WIRING4960150APU - SHORT - EGT SENSOR/CIRCUIT 1 WIRING4960154APU - OPEN CKT - EGT SENSOR/CKT 2 WIRING4960155APU - SHORT - EGT SENSOR/CIRCUIT 2 WIRING4960164APU - SHORT CKT-FCU [SHUT OFF SOL]/WIRING4960165APU - OPEN CKT-FCU [SHUT OFF SOL]/WIRING4960176APU - FCU [TRQ MOT SINGLE COIL OPEN CKT]4960177APU - OPEN CKT - FCU/FCU TORQUE MOTOR WRG4960179APU - SHORT - FCU/FCU TORQUE MOTOR WRG4960181APU - SHORT - INLET PRESS SENSOR/EXC WRG4960182APU - OPEN CKT-INLET PRESS SENSOR/EXC WRG4960189APU - INLET PRESSURE SENSOR [SIG OUT HI]4960190APU - INLET PRESSURE SENSOR [SIG OUT LO]4960191APU - OPEN CKT- INLET PRESSURE SENSOR/WRG4960192APU - SHORT- INLET PRESS SNSR/POS SIG WRG4960193APU - GROUND SHORT- INLET TEMP SENSOR/WRG4960194APU - INLET TEMP SENSOR [SIGNAL OUT HIGH]4960195APU - INLET TEMP SENSOR [SIGNAL OUT LOW]4960196APU - OPEN CKT - INLET TEMP SENSOR/WIRING4960197APU - SIG SHORT- INLET TEMP SENSOR/WIRING4960212APU - SHORT CKT-LCV/LCV TORQUE MOT WIRING4960213APU - OPEN CKT - LCV/LCV TORQUE MOT WIRING4960222APU - SHORT - FUEL SOLENOID VALVE/WIRING4960223APU - OPEN CKT-FUEL SOLENOID VALVE/WIRING4960281APU - LOAD CONT VLV (LCV POSITION VS CMD)4960300APU - SHORT CIRCUIT - SURGE VALVE/WIRING4960301APU - OPEN CIRCUIT - SURGE VALVE/WIRING4960321APU - POS VS CMD-INLET DOOR LIN ACTR/XDCR

   1. If any of the following active faults show on the CAIMS PMAT, troubleshoot them first.
   2. If any of the following active faults does not show on the CAIMS PMAT, continue with next step.

2. Get access to the active faults Stored Faults in CAIMS on the PMAT.

   1. If any APU related active/stored faults (list above) or non communicating LRU are shown, troubleshoot them first.
   2. If no APU faults are active and the APU SHUTDOWN (Advisory) is still shown on EICAS display, continue with next step.

3. 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.
   2. If no defects are found, continue with next step.

4. Perform the Operational Test of the Inlet Door. The FADEC will cause the inlet door to open fully. On the APU Control Panel, DO NOT select START, select RUN only. Verify visually that the APU air intake inlet door opens fully. Verify on the APU DATA status page, inlet door position indicated.

   1. If defects are found, rectify as required.
   2. If no defects are found, continue with next step.

5. Check inlet duct and top of oil cooler forward section for blockage using a borescope through the inlet door. (APU switch to Run only)

   1. If the inlet-duct forward section has blockage, remove blockage.
   2. If system checks are good, continue with next step.

6. Re-rack the APU FADEC.

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

7. Replace fuel control unit.

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

8. Replace the fuel solenoid valve.

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

9. Replace the Fuel flow-divider valve.

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

10. Replace the APU.
11. Do close out.