# SDR AALA202510103967

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: October 6, 2025
- Submitted: October 10, 2025
- Operation: Air carrier
- Aircraft: [N521UW](https://openairdocs.org/aircraft/N521UW), registered now
- Make and model: Airbus A321-231
- Registry model: [Airbus A321-231](https://openairdocs.org/model/airbus-a321-231) (OpenAirDocs)
- Aircraft serial: 3944
- Aircraft time: 52,598 hours, 20,179 cycles
- System (JASC): [4920 · APU Core Engine](https://openairdocs.org/jasc/4920)
- Part: Apu
- Part number: 38007081WGEN
- Part serial: P3760
- Condition: Odor
- Location: Zone 100
- Part time: 42,735 hours, 20,000 cycles
- Stage of operation: CL
- How discovered: O
- Nature of condition: B
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/AALA202510103967

## Discrepancy

AIRCRAFT WAS GROUNDED: SOF EVENT AFTER TAKEOFF, THEN DISSIPATED MIC 1580902. MAINTENANCE DETERMINED APU WAS SOURCE OF ODOR AND REPLACED APU IAW J/C 26L31049003.

---
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.