SDR UALA2009112503664

Service difficulty report · Controller · Boeing 747422

Difficulty date: November 25, 2009
Submitted: November 25, 2009
Operation: Air carrier
Aircraft: N120UA
Make and model: Boeing 747422
Aircraft serial: 29166
Aircraft time: 43,383 hours, 5,179 cycles
Engine: Pwa PW4056
System (JASC): 4900 · Airborne Auxiliary Power Unit (APU) System
Part: Controller
Part number: 77328918
Part serial: 235
Condition: Popped
Location: Apu
Stage of operation: CR
How discovered: O
Nature of condition: J
Precautionary procedure: J, A

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

What was found

APU ELEC STANDBY CIRCUIT BREAKER POPPED, RTFL. REPLACED THE NR 4 ENG HIGH PRESSURE CONTROLLER, NR 4 ENG PRESSURE REGULATING VALVE AND REPLACED THE NR 4 ENG PRESSURE REGULATING VALVE CONTROLLER. ALSO, CHK'D THE SECURITY OF THE BLEED LINES. ALL CHECKS ARE GOOD. ACCOMPLISHED ENG RUN FOR PRV, PRV CONTROLLER AND HPC REPLACEMENT. NO FAULTS NOTED.