# SDR ASAA2020120533656

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: December 5, 2020
- Submitted: December 11, 2020
- Operation: Air carrier
- Aircraft: [N478AS](https://openairdocs.org/aircraft/N478AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 44105
- Aircraft time: 20,503 hours, 6,599 cycles
- System (JASC): [4990 · APU Oil System](https://openairdocs.org/jasc/4990)
- Part: Oil Cooler
- Part number: 1605642
- Part serial: 7285
- Condition: Leaking
- Location: Apu
- Part time: 6,329 hours, 12,004 cycles
- Stage of operation: NR
- How discovered: O
- Nature of condition: K
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2020120533656

## Discrepancy

APU TREND DATA IS SHOWING AN INCREASE IN OIL USAGE.  GROUNDED-YES.  FOUND APU OIL COOLER LEAKING.  APPROXIMATELY ONE DROP PER MIN.  REMOVED AND REPLACED APU OIL COOLER, PER B737-900 AMM 49-91-41.  GROUND OPERATIONS CHECK IS GOOD.  NO LEAKS AT THIS TIME.

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