# SDR CALA2026102220512

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: October 18, 2026
- Submitted: October 22, 2026
- Operation: Air carrier
- Aircraft: [N27958](https://openairdocs.org/aircraft/N27958), registered now
- Make and model: Boeing 787-9
- Registry model: [Boeing 787-9](https://openairdocs.org/model/boeing-787-9) (OpenAirDocs)
- Aircraft serial: 36406
- Aircraft time: 52,063 hours, 4,979 cycles
- System (JASC): [3350 · Emergency Lighting](https://openairdocs.org/jasc/3350)
- Part: Battery
- Part number: 100260201
- Part serial: ST21106527
- Condition: Inoperative
- Location: Zone 200
- Part time: 23,530 hours, 2,279 cycles
- 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/CALA2026102220512

## Discrepancy

AHM DETECTED WELS MSG 33-12130.  REMOTE WELS CONTROL UNIT CONFIGURATION DOES NOT AGREE WITH OTHER WIRELESS EMERGENCY LIGHTING SYS CONTROL UNITS.  REF FIM DMC-B787-A-33-50-F1-P2A-421A-A TO CONFIRM FAULT.  REF CONFIG DWG 2500DD15922 TO AID LOCATING WCU CLASS 30.1 M3351031 ON SIDE OF OFCR, ABOVE FIRST CEILING PANEL, LT AISLE.  PERFORMED EMERGENCY LIGHTS FULL GROUND TEST IAW FIM 33-50-F1-P2A-421A-A. TEST FAILED WITH IDENTICAL MAINT MSG.  R & R CLASS 30 WBU IAW AMM 33-51-07-2B.  PAIRED WITH WCU 30 IN NETWORK IAW FIM & NO FIX. R & R CLASS 30 WCU WITH NEWLY INSTALLED BATTERY IAW AMM 33-51-07-01B. OPS & DATABASE SOFTWARE LOADED. OPS CHKD GOOD.  FULL EMERGENCY LIGHTS GROUND TEST PASSED. OK FOR SERVICE.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.