Service difficulty report · Software · Boeing 7878

Difficulty date
August 27, 2025
Submitted
August 28, 2025
Operation
Air carrier
Aircraft
N20904
Make and model
Boeing 7878
Aircraft serial
34824
Aircraft time
49,446 hours, 6,345 cycles
Part
Software
Condition
Missing
Location
Zone 200
Stage of operation
IN
How discovered
V
Nature of condition
W
Precautionary procedure
K

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

What was found

FOUND FWD HALF OF ECONOMY SEATS EMERGENCY LIGHTS WOULD NOT COME ON WITH EMERGENCY SWITCH IN ON POSITION DURING INSTALLATION TEST - CMCF SHOWS CODES 33-11624 AND 33-11726; CLASS 24,26 REMOTE WELS LAMP DRIVER POWER CIRCUIT IS FAILED. REMOVED AND INSTALLED NEW WELS UNITS 24.1, 24.2, AND 26. REF AMM DMC-B787-A-33-51-07-01A-720A-A. PERFORMED SOFTWARE LOAD OF WELS NETWORK. SOFTWARE LOAD AND NETWORK BUILD SUCCESSFUL. OPS CHECK NO GOOD. FWD HALF ECONOMY STILL WOULD NOT ILLUMINATE. REINSTALLED ORIGINAL WELS UNITS 24.1, 24.2, AND 26. SWAPPED WCU #26 AND #27 NO JOY. SWAPPED BACK TO ORIGINAL POSITIONS. FOUND SOFTWARE MISSING FROM PRIMARY WCU AT 3L. RELOADED SOFTWARE PER MM 33-51-07. ACCOMPLISHED FULL EMERGENCY LIGHTS GROUND TEST PER MM33-51-00. TEST PASSED NO FAULTS. ALL EMERGENCY LIGHTS CHECK GOOD.

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