SDR CALA2025082908264

Service difficulty report · Control Unit · Boeing 7879

Difficulty date: August 28, 2025
Submitted: August 29, 2025
Operation: Air carrier
Aircraft: N15969
Make and model: Boeing 7879
Aircraft serial: 60142
Aircraft time: 40,359 hours, 3,961 cycles
System (JASC): 3350 · Emergency Lighting
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

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

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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