# SDR CALA2026021013658

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: February 8, 2026
- Submitted: February 10, 2026
- Operation: Air carrier
- Aircraft: [N24973](https://openairdocs.org/aircraft/N24973), registered now
- Make and model: Boeing 787-9
- Registry model: [Boeing 787-9](https://openairdocs.org/model/boeing-787-9) (OpenAirDocs)
- Aircraft serial: 40941
- Aircraft time: 38,462 hours, 3,645 cycles
- System (JASC): [3350 · Emergency Lighting](https://openairdocs.org/jasc/3350)
- Part: Light
- Part number: 0204338101
- Condition: Inoperative
- 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/CALA2026021013658

## Discrepancy

AHM DETECTED WELS MSG 33-11229,   REMOTE WELS CONTROL UNIT HAS AN INTERNAL FAULT.  REF DMC-B787-A-33-50-F1-43A-421A-A TO CONFIRM FAULT.  REF CONFIGURATION DWG 2500DD15922 TO AID LOCATING CLASS 29.1 WCU M3351WG01 UNDER SEAT 57D.   REPLACED CLASS 29 WCU IAW AMM DMC-B787-A-33-51-07-01A-520A-A. NO HELP, MX MSG STILL ACTIVE. TRIED INSTALLING A SECOND NEW CLASS 29 WCU. 33-11229 NOT ACTIVE BUT IS NOW FAULTING MX MSG 33-11729.   SLAVED IN NEW BATTERY WITH OLD WCU, NO HELP. INSTALLED NEW WCU WITH OLD BATTERY. STILL NO HELP. SOFTWARE CHECKS OKAY. FAULT MSG 33-11729. 6 ROWS OF LIGHTS INOPERATIVE FROM ROW 50 TO AFT OF ACFT.   REPLACED THE HIGHER INTENSITY FLOOR PROXIMITY LIGHTS ROWS AFT OF ROW 50.  EMERGENCY LIGHTS TESTED OK. NO ACTIVE MESSAGES NOTED. REF FIM 33-50-F1-E9A-421A-A.

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