What was found
UNSCHEDULED LANDING DUE TO ELECTRICAL PROBLEMS. FLIGHT CREW REPORTED A SUSTAINED LOSS OF CAPTAINS INSTRUMENTS IN FLIGHT. BOTH CAPTIANS EFIS DISPLAYS WENT BLANK, THE NO.1 GENERATOR BUS DROPPED OFF LINE, THE NO.2 BUS FAILED TO PICK UP THE NO.1 TRANSFER BUS LOAD, AND THE C819 NO.1 TRANSFER BUS NORMAL CIRCUIT BREAKER TRIPPED. SUPPLEMENTAL DATA UPDATE THE PROBLEM COULD NOT BE DUPLICATED ON THE GROUND. THE NO. 1 TRANSFER BUS NORMAL RELAY (R3) WAS REPLACED. IN ADDITION, THE NO.1 AND NO.2 GENERTAOR CONTROL UNITS WERE REPLACED AS PRECAUTIONARY. TAXI RUNS FAILED TO DUPLICATE THE PROBLEM, AND THE AFFECTED SYSTEMS OPERATED NORMALLY.