What happened
Following a landing, the pilot was maneuvering the aircraft into the ramp area when he observed an orange glow near his feet. The pilot immediately notified airport personnel via radio regarding an ongoing fire within the airplane. After bringing the aircraft to a complete stop, airport crash fire rescue responded and extinguished the flames.
The investigation
An examination of the aircraft revealed that the fire had burned a hole through the fuselage skin in the area of the Janitrol heater, located just aft of the left wing root. The fire consumed the entire section of the aircraft forward of the Janitrol heater, which included the cockpit and cabin, as well as the heater's plumbing and wiring.
Findings
Investigation into the pilot's procedures showed that his standard practice for using the Janitrol heater was to turn it off simultaneously with the extension of the landing gear during the approach phase. However, the Pilot's Operating Handbook (POH) advised placing the heat control switch in the fan position for several minutes after operation to allow the unit to cool before being turned off. Furthermore, the POH Normal Procedures required the switch be set to the fan position during the completion of the Before and After Landing checklists, with the shutdown checklist specifying that the switch be moved to the OFF position.