As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TROUBLESHOOTING NON ESSENTIAL BUSS 1 FAILURE THERE WAS A LOUD POP FROM 1VE PANEL, AND FIRE OCCURRED ON INSULATION AND SURROUNDING WIRES. REMOVED AND REPLACED 1VE PANEL AND BUS POWER CONTROL UNIT (BPCU). NO FURTHER OCCURRENCES, NO REPEATS. SUSPECT INTERNAL FAILURE TO THE 1VE CONTACTOR AT THE NON-ESSENTIAL BUS 2. (M)