As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT HEATER EMITTED A WHITE HAZE INTO THE CABIN WHEN TURNED ON. FURTHER INVESTIGATION DISCOVERED THAT THE HEATER HAD NOT BEEN USED DURING RECENT SUMMER MONTHS. THIS HAD BEEN THE FIRST ACTIVATION OF THE AIRCRAFT HEATER OF THE FALL SEASON. HEATING SYSTEM WAS FULLY INSPECTED WITH NO ABNORMALITIES DISCOVERED. HEATER WAS THEN OPERATED WITH SATISFACTORY RESULTS BOTH ON THE GROUND AND IN THE AIR DURING AIRCRAFT OPERATION.