What was found
NR 1 MAIN FUEL TANK FORWARD BOOST PUMP FOUND INOPERATIVE. PUMP WAS PLACARD INOPERATIVE. MX FOUND PUMP TO BE EXTREMELY HOT DURING TROUBLESHOOTING. CONNECTOR COULD NOT BE REMOVED & WIRING HAD MELTED OFF PUMP. APPROX 6 INCHES OF WIRING HARNESS WAS BURNED & CONNECTOR WAS BURNED. RELATED CIRCUIT BREAKER HAD NOT POPPED. BOOST PUMP CONNECTOR PINS BURNED. ARCING OF PINS HAS BEEN ADDRESSED IN BOEING SERVICE BULLETIN 777-28-0028. VENDOR TEARDOWN FOUND THAT THE PRIMARY CAUSE OF THE PIN FAILURE TO BE CONTAMINANT INGRESS/PRESENCE. CONTAMINANT COMBINED WITH FRETTING DAMAGE TO GOLD LAYER OF PINS RESULTS IN GALVANIC CORROSION DAMAGE BETWEEN THE PINS AND AIRCRAFT FEMALE SOCKETS.