# SDR SWAA2025090912055

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: September 5, 2025
- Submitted: September 9, 2025
- Operation: Air carrier
- Aircraft: [N8579Z](https://openairdocs.org/aircraft/N8579Z), registered now
- Make and model: Boeing 737-8H4
- Registry model: [Boeing 737-8H4](https://openairdocs.org/model/boeing-737-8h4) (OpenAirDocs)
- Aircraft serial: 63591
- Aircraft time: 23,553 hours, 12,211 cycles
- System (JASC): [4990 · APU Oil System](https://openairdocs.org/jasc/4990)
- Part: O-Ring
- Condition: Leaking
- Location: Apu Oil Cooler
- Stage of operation: TX
- How discovered: O
- Nature of condition: K, B
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/SWAA2025090912055

## Discrepancy

APU AIR CAUSES SMOKE AND VAPOR TO FILL THE CABIN.   FOUND APU OIL COOLER INPUT-OUTPUT LINES O-RINGS DAMAGED. REPLACED APU OIL COOLER LINE O-RINGS PER AMM 49-91-41. A/COK FOR SERVICE.

---
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.