# SDR CALA2025082908264

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: August 28, 2025
- Submitted: August 29, 2025
- Operation: Air carrier
- Aircraft: [N15969](https://openairdocs.org/aircraft/N15969), registered now
- Make and model: Boeing 787-9
- Registry model: [Boeing 787-9](https://openairdocs.org/model/boeing-787-9) (OpenAirDocs)
- Aircraft serial: 60142
- Aircraft time: 40,359 hours, 3,961 cycles
- System (JASC): [3350 · Emergency Lighting](https://openairdocs.org/jasc/3350)
- Part: Control Unit
- Part number: 100260103
- Condition: Faulted
- 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/CALA2025082908264

## Discrepancy

DURING SOFTWRE CHECK OF NR 9 AND 30 WELS BATTERY FOUND NOT IN NET FOR WBUS 02,09,17,21, AND 30.  REMOVED AND REPLACED WELS CONTROL UNIT AT L1 IAW AMM B787-A-33-51-07-01A-520A-A AND B787-A-33-51-07-01A-720A-A REFERENCE FIM 33-50-F1-FAA-421A. SOFTWARE LOADED AND OPS CHECK GOOD, ALL RELATED FAULTS FOR WELS BATTERIES CLEARED.

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