What happened
The pilot performed a standard preflight inspection of the Mooney aircraft, noting only a discrepancy with the cabin entry door seal and adding one quart of oil to the engine. After departing from runway 32, the aircraft was climbing between 2,500 and 2,800 feet when thick black smoke suddenly filled the cockpit. The pilot observed flames underneath the instrument panel, located behind the rudder pedals on both sides of the cockpit.
In response to the fire, the pilot turned off the master switch and began a descending left turn with the intention of ditching the aircraft. After reducing the mixture control and opening the cabin entry door, the pilot determined that visibility allowed for a return to the airport. The pilot briefly reactivated the master switch and lowered the landing gear to land on runway 14. Following touchdown, the aircraft exited the north side of the runway onto the grass. The pilot evacuated through the cabin door. While no fire department was stationed at the airport, a nearby unit arrived and extinguished the fire.
There were no fatalities or injuries reported in the accident.
The investigation
An FAA Airworthiness inspector-in-charge found that fire had consumed the upper and side fuselage skin of the cockpit and cabin area. Damage was also noted on the inboard portion of the right wing, including the area of the right fuel tank. Burn damage was identified on plastic brake system tubing located forward of the rudder pedals.
The investigation focused on the tailpipe assembly, which was found separated from the turbocharger exhaust turbine housing. The coupling used to secure the tailpipe to the turbocharger was resting on the tailpipe rather than in its installed position. No safety wire was present, and the nut was not recovered. While the threads of the Aeroquip coupling showed no damage, examination of other exhaust system components revealed deterioration that should have been identified during an inspection performed 1.8 hours prior to the accident.
Maintenance records showed the engine had been overhauled in 1996, and a repair to the exhaust stack was noted in March 2001. The mechanic who performed the most recent annual inspection reported removing the tailpipe and turbocharger wastegate for cleaning and reinstalling the tailpipe using the same nut.