# SDR ASAA2017041920490

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: April 19, 2017
- Submitted: April 21, 2017
- Operation: Air carrier
- Aircraft: [N566AS](https://openairdocs.org/aircraft/N566AS), registered now
- Make and model: Boeing 737890
- Aircraft serial: 35182
- Aircraft time: 39,472 hours, 11,824 cycles
- System (JASC): [4900 · Airborne Auxiliary Power Unit (APU) System](https://openairdocs.org/jasc/4900)
- Part: Apu
- Condition: Malfunctioned
- Stage of operation: CR
- How discovered: O
- Nature of condition: J
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2017041920490

## Discrepancy

APU FAULT LIGHT ILLUMINATED ON 1ST APU START ATTEMPT AT FL360. RAN QRH , FAULT LIGHT WENT OUT WITHIN 5 MINS.  ACFT GROUNDED.   APU BITE TEST SHOWS MSG 49-31171 FUEL CONTROL UNIT FLOW DISAGREES WITH COMMAND. APU DID START ON 2ND ATTEMPT IN FLIGHT PER SEAMC. PERFORMED FIM 49-31TASK 808, FUEL FLOW DIVIDER HYDRAULIC LOCK PROCEDURE IAW AMM 49-31-15/401. APU STARTED AND OPS NORMAL. NO OTHER FAULTS. GROUND VERIFICATION GOOD.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.