What was found
STUDENT PILOT AND INSTRUCTOR REPORTED RADIOS QUIT AFTER A LOUD BUZZING SOUND WAS HEARD THROUGH THE HEADSETS FOR A FEW SECONDS. RADIOS STARTED FUNCTIONING NORMALLY A FEW SECONDS AFTER. BETWEEN 15 - 20 MINUTES LATER SMOKE STARTED COMING FROM BEHIND THE PANEL, ORANGE LIGHT COMING FROM THE AMMETER, AND SPARKS WERE FALLING ON THE PILOT’S LEG. AMMETER OUTPUT CIRCUIT BREAKER TRIPPED AND GAUGE STOPPED PRODUCING SPARKS, SMOKE, AND LIGHT. PILOTS FLEW THE REMAINING 8 MILES TO THE DESTINATION AIRPORT ON BATTERY POWER. REMOVAL OF AMMETER AND GAUGE CLUSTER HOUSING REVEALED INSULATORS ON THE LEFT POST AS VIEWED FROM PILOT SEAT WERE DESTROYED AND INSTRUMENT CLUSTER METAL CASE WAS DAMAGED. RIGHT POST NUTS AND INSULATORS WERE STILL SNUG AND UNDAMAGED. AD 86-17-01 HAD BEEN COMPLIED WITH.