Incident Description
During the climb to cruise altitude, the airplane's engine compartment caught fire. Ground witnesses reported observing flames emanating from the nose wheel area. In response, the crew initiated an emergency descent. During this descent, the airplane struck tree tops before colliding with the terrain.
Post-Accident Examination
Examination of the engine after the accident revealed that the left intermediate exhaust pipe had separated from the left cross-over exhaust pipe. This separation allowed hot gases to vent directly into the engine compartment. The flange of the left intermediate pipe was found cracked. Additionally, the engagement length between the left intermediate pipe and the cross-over pipe measured less than the required 1.5 inches. A clamp that secures the exhaust pipes to the accessory case was missing.
Maintenance Findings
Further inspection disclosed that numerous airworthiness directives had not been complied with. The exhaust system installed on the accident engine was not the correct system as specified. The last annual inspection of the airplane was performed on July 30, 1993, approximately 3 flight hours prior to the accident flight.