Service difficulty report · Transformer · Boeing 777222

Difficulty date
December 30, 1996
Submitted
March 26, 2000
Operation
Air carrier
Aircraft
N773UA
Make and model
Boeing 777222
Aircraft serial
26929
Engine
Pwa PW4077
Part
Transformer
Part number
S906709037
Condition
Failed
Location
Cockpit
Component
Boeing · 285W00122
Stage of operation
NR
Nature of condition
B
Precautionary procedure
F

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

What was found

CABIN CONTROL PANEL 4R SMOKING. USED TWO HALON BOTTLES TO EXTINGUISH SMOKE. *S/D* MULTIPLE COMPONENT FAILURES WITHIN THE CACP TXFMR T961, BACKLIGHT NR 2 BOTH FILAMENTS OPEN, POWER SUPPLY HEATER RESISTORS R995, R996, R997 AND R998 AND ASSOCIATED CIRCUIT TRACES BURNED. PREVIOUS HISTORY ON CACP UNITS INDICATED OVERHEAT COULD RESULT ONLY IF BOTH BACKLIGHTS FAILED OPENED. THIS UNIT FAILED WITH ONLY ONE LIGHT OUT. MAINTENANCE TIP PUBLISHED TO PULL AND COLLAR THE CACP CIRCUIT BREAKER WHEN A BACKLIGHT FAILS AND REPLACEMENT NOT AVAILABLE. BOEING STILL INVESTIGATING.