Incident Sequence
During flight, the pilot observed smoke in the cockpit and began a precautionary landing at Mexia, Texas, which was nearby. However, during the descent, the smoke dissipated, prompting the pilot to elect to continue to the destination. As the aircraft climbed back to altitude, the smoke reappeared and was followed by a loss of engine power. The pilot then attempted a forced landing at Mexia but did not have sufficient altitude to reach the airport. While landing approximately one mile from the airport, the aircraft rolled through a barbed wire fence and sustained damage.
Examination and Findings
An examination of the aircraft revealed that a retaining nut was missing from a clamp near two mating surfaces of the exhaust system around the number six cylinder. Subsequently, gases from the exhaust system burned through a vacuum hose and extensively burned a number of wires in the ignition system. The aircraft had accumulated 176 hours of flight time since the last engine and airframe inspection.