# SDR AALA202605111815

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: May 9, 2026
- Submitted: May 11, 2026
- 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: 54,267 hours, 20,909 cycles
- System (JASC): [3350 · Emergency Lighting](https://openairdocs.org/jasc/3350)
- Part: Battery
- Part number: AD321431
- Condition: No Test
- Location: Zone 200
- Stage of operation: IN
- How discovered: C
- Nature of condition: L
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/AALA202605111815

## Discrepancy

AIRCRAFT WAS NOT GROUNDED: FAULT MESSAGE FOR AFT LEFT EMERGENCY POWER SUPPLY UNIT DISPLAYED DURING SYSTEM TEST. MAINTENANCE REPLACED THE EMERGENCY POWER SUPPLY UNIT (AALA202605090506) AND BATTERY (AALA202605116775) PER AMM 33-51-38. A SATISFACTORY OPERATIONAL CHECK OF THE EMERGENCY LIGHTING SYSTEM WAS ACCOMPLISHED WITH NO FAULTS NOTED.

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