What was found
PILOT REPORTED SMOKE IN COCKPIT 30 MINUTES INTO FLIGHT. CONNECTOR FROM PROPELLER HEAT CIRCUIT BREAKER (P-186/J-186). CONNECTOR, 12 GAUGE WIRE(HA-36). MAINTENANCE CREW FOUND CONNECTOR FULLY ENGAGED AND STILL ATTACHED TO WIRE BUNDLE. MAINTENANCE FOUND TERMINAL PINS INSIDE CONNECTOR LOOSE CAUSING HIGH RESISTANCE WHICH RESULTED IN HEATING AND BURNING OF PLUG. SINCE THERE IS HIGH CURRENT DRAW IN THIS CIRCUIT AND THOUGH THIS CONNECTOR IS RECOMMENDED THAT THE PINS AT THIS CONNECTOR BE CHECKED FOR PROPER TIGHTNESS AND ENGAGEMENT.