SDR AALA202204188709

Service difficulty report · Control Unit · Boeing 737

Difficulty date: April 12, 2022
Submitted: April 18, 2022
Operation: Air carrier
Aircraft: N836AA
Make and model: Boeing 737
Aircraft serial: 40654
Aircraft time: 14,805 hours, 1,790 cycles
System (JASC): 3350 · Emergency Lighting
Part: Control Unit
Condition: Faulty
Location: Zone 200 - Fuse
Stage of operation: IN
How discovered: V
Nature of condition: O
Precautionary procedure: K

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

What was found

AIRCRAFT WAS GROUNDED: DURING ACCOMPLISHMENT OF WORK CARD 78T21033001, FAULT CODE 33-12107 SHOWS. REMOVED AND REPLACED WELS CONTROL UNIT NUMBER 07 PER AMM 33-51-07. WELS CONTROL UNIT 07 FAILS GROUND TEST. SUSPECT WCU07 BAD FROM STOCK. HAS AN ACTIVE FAULT 33.11207, INTERNAL FAILURE. REF FIM 33-51-F1-30A-421A. WCU07 REQUIRES REPLACEMENT. REMOVED AND REPLACED WELS CONTROL UNIT (AALA202204148486) 07 ABOVE L4 DOOR PER AMM 33-51-07.