As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HEATER SHOWED SIGNS OF ABNORMAL COMBUSTION IE. SOOT TRAIL FROM FUEL DRAIN VENT. UPON INVESTIGATION. FOUND COMBUSTION AIR BLOWER FAN WHEEL ASSY HAD COME APART AND FODED HEATER. FAN MOTOR WOULD STILL RUN. AIR PRESSURE SWITCH HAD FAILED IN CLOSED POSITION IAW AD, SWITCH DOESN`T NEED OPS TESTING. RECOMMENDED THAT ALL COMBUSTION AIR PRESSURE SWITCHES, BE TESTED AND THAT THE COMBUSTION AIR FAN WHEEL ASSY BE INSPECTED AT SAME INTERVALS AS IN AD. (K)