# SDR AALA202603064157

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: February 19, 2026
- Submitted: March 6, 2026
- Operation: Air carrier
- Aircraft: [N921US](https://openairdocs.org/aircraft/N921US), registered now
- Make and model: Airbus A321-231
- Registry model: [Airbus A321-231](https://openairdocs.org/model/airbus-a321-231) (OpenAirDocs)
- Aircraft serial: 6523
- Aircraft time: 32,691 hours, 13,297 cycles
- System (JASC): [4990 · APU Oil System](https://openairdocs.org/jasc/4990)
- Part: Garlock Seal
- Condition: Leaking
- Location: Apu
- Component: Apu, Hnywl, 1319A
- Component part number: 38007081
- Stage of operation: DE
- 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/AALA202603064157

## Discrepancy

AIRCRAFT WAS GROUNDED: APU OFF DESCENDING THROUGH 10000, FLIGHT CREW NOTED A DIRTY SOCK SMELL IN FLIGHT DECK. **ORIGINAL REPORT WAS AALA202602236304 SUBMITTED 2/23/2026 BY TUL** MAINTENANCE FOUND EVIDENCE OF COKING IN THE APU GEARBOX VENT TUBE AND REPLACED IT PER AMM 49-26-55. MAINTENANCE ALSO REPLACED THE APU GEARBOX AIR-OIL SEPARATOR GARLOCK SEALS PER AMM 49-26-54 (AALA202603064157). A DECONTAMINATION OF THE ENVIRONMENTAL CONTROL SYSTEM WAS ACCOMPLISHED PER TASK CARDS 26L00021002. A SATISFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO LEAKS OR ODORS NOTED.

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