As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) THE AIRCRAFT WAS IN LEVEL FLIGHT. THE AFT HEATER WAS BROUGHT ON LINE. A SHORT TIME LATER, THE PASSENGERS NOTED SMOKE AND SPARK'S COMING FROM THE OUTLET. THE HEATER WAS SHUT DOWN AND THE CABIN FIRE EXTINGUISHER WAS DISCHARGED INTO THE INLET. THE AIRCRAFT LANDED AND MAINTENANCE DISCOVERED THE CYCLE SWITCH HAD MALFUNCTION.