Incident Summary
On March 21, 2008, at 2206 central daylight time, a Piper PA-34-200T, registration N66AH, was destroyed in an on-ground fire while taxiing at Covington Municipal Airport (M04), Covington, Tennessee. The pilot, a certificated airline transport pilot, was not injured. Night visual meteorological conditions prevailed, and no flight plan was filed. The personal flight was destined for Charles W. Baker Airport (2M8), Millington, Tennessee, and was conducted under 14 Code of Federal Regulations Part 91.
According to the pilot, the purpose of the flight was to practice takeoffs and landings at night. He departed his home base at 2M8 around 2230, flew to and landed at an intermediate airport, then flew to and landed at M04. While taxiing the airplane to the hold short line of runway 01, he saw a flicker of light in his peripheral vision. He looked aft and observed a flame behind the aft cabin seats. He immediately shut down both engines and exited the airplane. Peering into the cabin through the aft-most, co-pilot side window, he saw flames reaching up to about the bottom of the window. He then retreated and telephoned for assistance. The airplane was subsequently consumed by the fire.
Aircraft and Equipment
The airplane was equipped with a combustion-type heater, of the type originally installed during manufacture, located in the area where the pilot reported seeing the fire. The heater was operating at the time of the accident. The heater was forwarded to the Safety Board Materials Laboratory for examination. The laboratory report identified the heater as a Janitrol B-series type. The fire destroyed the identification tag containing the model and serial number.
The heater was severely thermally damaged throughout the entire assembly. Examination of the heater did not identify any fire damage that could have been causal or associated with the initiation of a fire. The heater was completely disassembled and each component was examined for signs of a failure that could have initiated the fire. The fuel drain line was found intact and unobstructed. The combustion chamber was intact with no visible cracks. The combustion air blower rotated freely and its motor's brushes were intact. The ventilation air blower also rotated freely and its motor's brushes were intact.
The combustion air pressure switch had a cracked housing that was partially open. The switch had three connection terminals; the COMMON and NORMALLY OPEN terminals were connected to wires, while the NORMALLY CLOSED terminal was not used. Conductivity was present between all terminals. The fire destroyed the mechanism of the switch's rocker arm, so movement of the rocker arm would not change the state of the switch. The pressure-sensing portion of the switch was severely damaged by the fire, and its pre-fire condition could not be determined.
The fuel pump that fed the combustion heater was not recovered and could not be examined.
Pilot and Maintenance
The pilot stated that the airplane’s maintenance records were onboard when the fire occurred and were not recovered. He also stated that the airplane’s most recent annual inspection was completed on May 1, 2007. Federal Aviation Administration aircraft registration data revealed that the pilot purchased the airplane on September 9, 2007.