# SDR USAA2012010600026

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: January 4, 2012
- Submitted: January 6, 2012
- Operation: Air carrier
- Aircraft: [N438US](https://openairdocs.org/aircraft/N438US), registered now
- Make and model: Boeing 737-4B7
- Registry model: [Boeing 737-4B7](https://openairdocs.org/model/boeing-737-4b7) (OpenAirDocs)
- Aircraft serial: 24560
- Aircraft time: 58,056 hours, 38,690 cycles
- System (JASC): [2120 · Air Distribution System](https://openairdocs.org/jasc/2120)
- Part: Filter
- Part number: 21FA507
- Condition: Dirty
- Location: Cabin
- Stage of operation: AP
- How discovered: O
- Nature of condition: B
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/USAA2012010600026

## Discrepancy

ON APPROACH, FLIGHT ATTENDANT REPORTED A STRONG SMELL LIKE DIRTY SOCKS IN CABIN, PROGRESSIVELY STRONGER WHEN MOVING FROM AFT OF AIRCRAFT TO FORWARD CABIN.  SMELL NOT NOTICEABLE IN COCKPIT.  SMELL DISSIPATED/COMPLETED ONCE AIRCRAFT LANDED.  MAINTENANCE ACCOMPLISHED J/C 03L21021001 AND 03L21021003 AND REMOVED AND REPLACED LEFT AND RIGHT HEPA FILTERS.  ALSO, ACCOMPLISHED DUCT CLEANING PER AMM 21-00-01-102-001.

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