04/08/21
Message Overview:
Message Description:
Auxiliary Power Unit (APU) protective shutdown - APU speed did not reach 5%.
Possible Causes:
- Starter Motor Assembly
- Auxiliary Power Unit (APU)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Fault Confirmation Procedure:
- Message# = 4
- {Term Definitions}
- APU-38 XX 352 01 EXCT XXXX-XXXX XXXT-XXXX XXXX-XXXX 352: 21; APU S/D NO CRANK
Quick Links:
| Removal of the Auxiliary Power Unit (APU) | AMM 49-11-01-000-801 |
| Installation of the Auxiliary Power Unit (APU) | AMM 49-11-01-400-801 |
| Removal of the Starter Motor | AMM 49-42-01-000-801 |
| Installation of the Starter Motor | AMM 49-42-01-400-801 |
| Removal of the Auxiliary Power Unit (APU) Electronic Control Unit (ECU) | AMM 49-61-01-000-801 |
| Installation of the Auxiliary Power Unit (APU) Electronic Control Unit (ECU) | AMM 49-61-01-400-801 |
| Wiring - Maintenance Practices - ALL | SPM 20-12-00-02 |
| Wire Repair - Maintenance Practices - ALL | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- This condition could be due to a mechanical failure of the starter motor assembly, a seized engine, or open circuit to the APU starter motor.