What was found
N442HA A CESSNA 441 WAS DECENDING THROUGH APPROX. 12000 FT WHEN THE PROPELLER DE-ICE AMP METER EXPLODED SENDING BROKEN GLASS INTO THE PILOT FACE JUST MISSING HIS EYES. PRIOR TO THE FAILURE THE PILOT HAD SELECTED THE PROPELLER DE-ICE SYSTEM TO THE ON POSITION. TO CYCLE THE SYSTEM PRIOR TO LANDING. THE PILOT SHUT DOWN THE PROPELLER DE-ICE SYSTEM FOLLOWING THIS INCIDENT. THE CIRCUIT PROTECTOR DID NOT OPEN WITH THIS FAILURE. THE GAGE WAS REMOVED AND INSPECTED THE SHUNT LOCATED IN THE BACK OF THE GAGE HAD BURNED AND MELTED OPENING THE CIRCUIT.