What was found
DURING CRUISE FLIGHT, THE POWER DISTRIBUTION BOX (PDB) SWITCHED FROM NORMAL-AUTO MODE TO ESSENTIAL BUSS-ON BATTERY-MODE WITHOUT NOTICEABLE INDICATION TO THE CREW. THIS CONDITION RESULTED IN A NEAR-TOTAL ELECTRICAL FAILURE CONDITION CAUSING A LOSS OF NAV, COMM, AND TRANSPONDER OPERATION. AIRCRAFT EN ROUTE FROM MCO TO BHM. THE CREW SWITCHED TRANSPONDERS TO CODE 7700 AS POWER WAS FAILING AND DIVERTED TO MGM FOR EMERGENCY LANDING USING EMERGENCY BATTERIES FOR NAVIGATION AND MAGNA STAR PHONE TO COMMUNICATE WITH ATC. ACFT LANDED AT MGM WITHOUT FURTHER INCIDENT. SUSPECT K15 RELAY INSIDE THE PDB FAILED. COMPONENT P/N 1159SCAV373801