What was found
THE PILOT ATTEMPTED TO USE THE HEATER ON A NEW AIRCRAFT WITHOUT SUCCESS. THE CIRCUIT BREAKER TRIPPED. REPAIRS WERE MADE TO OVERHEATED WIRING. HEATER FAILED AGAIN ON NEXT FLIGHT. MAINTENANCE REMOVED THE HEATER FROM THE AIRCRAFT FOR INVESTIGATION, WITH A TOTAL OF .5 HOURS ON THE HEATER HOBBS SINCE NEW. INTERNAL VENT BLOWER FAN (PIPER P/N 753-201) SEPARATED FROM HUB ARBOR. PRESSURE DIFFERENTIAL SWITCH (JAN AERO P/N 94E42-3). PNEUMATIC FITTING COMPLETELY STRIPPED IN UNIT BODY. LARGE DRILL SHAVING IN THE FUEL INLET LINE SOLENOID VALVE.