SDR 9514296623

Service difficulty report · Relay · Boeing 747251B

Difficulty date: September 16, 1995
Submitted: March 26, 2000
Operation: Air carrier
Aircraft: N623US
Make and model: Boeing 747251B
Aircraft serial: 21705
System (JASC): 2420 · AC Generation System
Part: Relay
Condition: Malfunctioned
Location: E/E Bay
Stage of operation: CR
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

THIRTY MINUTES INTO FLIGHT ESSENTIAL BUS POWER LIGHT ILLUMINATED. THE PROBLEM CONTINUED ON AND OFF FOR SEVERAL MINUTES AND GOT WORSE. CREW FOLLOWED COCKPIT OPERATING PROCEDURE, DUMPED 55,000 LBS OF FUEL AND RETURNED TO LAX. MAINTENANCE REPLACED R79 RELAY, RAN ALL FOUR ENGINES IN IDLE POWER AND WITH POWER FOR ABOUT 15 MINUTES, COULD NOT DUPLICATE PROBLEM.