What happened
While climbing to cruise altitude, the aircraft's engine compartment caught fire. Ground witnesses reported seeing flames emanating from the nose wheel area. In response to the fire, the pilot performed an emergency descent; however, the aircraft struck treetops before ultimately colliding with the terrain.
The investigation
Post-accident examination of the engine identified that the left intermediate exhaust pipe had separated from the left cross-over exhaust pipe. This separation allowed hot gases to escape directly into the engine compartment. Investigators found that the flange on the left intermediate pipe was cracked and the engagement between the left intermediate and cross-over pipe was less than the required 1.5 inches. Additionally, a clamp used to secure the exhaust pipes to the accessory case was missing.
Further inspection revealed that the exhaust system installed on the accident engine was not the correct system for the aircraft. The investigation also determined that numerous airworthiness directives had not been complied with. The aircraft's most recent annual inspection had been completed on July 30, 1993, approximately three flight-hours before the accident.