# SDR ASAA2023042543027

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: April 25, 2023
- Submitted: April 29, 2023
- Operation: Air carrier
- Aircraft: [N588AS](https://openairdocs.org/aircraft/N588AS), registered now
- Make and model: Boeing 737890
- Aircraft serial: 35685
- Aircraft time: 54,683 hours, 16,253 cycles
- System (JASC): [4900 · Airborne Auxiliary Power Unit (APU) System](https://openairdocs.org/jasc/4900)
- Part: Sensor
- Part number: 38762252
- Condition: Faulty
- Location: Apu
- 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/ASAA2023042543027

## Discrepancy

FAULT LIGHT ILLUMINATED DURING APU START ATTEMPT AT FL380. SUCCESSFUL CSS ACCOMPLISHED AFTER FAULT LIGHT EXTINGUISHED AT FL320. GROUNDED - YES. REF B737-800 FIM 49-40 TASK 801, REPLACED APU AIR INLET TEMP SENSOR (AMM 49-61-31)) AND AIR INLET PRESSURE SENSOR (AMM 49-52-31) STARTED APU AND SHUTDOWN NORMALLY. APU BITE SHOWS NO CURRENT FAULTS.

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