What happened
The pilot reported noticing smoke inside the cockpit while en route. At that time, the aircraft was in close proximity to Mexia, Texas, which offered a nearby suitable location for a precautionary landing. The pilot initiated a descent toward the airport to land; however, during this phase of the approach, the smoke dissipateed. Believing the issue had resolved, the pilot elected to continue the flight to the original destination rather than diverting.
Shortly after, as the aircraft began its climb back to cruising altitude, the smoke reappeared in the cockpit. This was quickly followed by a complete loss of engine power. With the engine no longer producing thrust, the pilot attempted to make a forced landing at Mexia. However, due to the altitude lost during the previous maneuvers and the subsequent power failure, there was insufficient height to reach the airport runway.
The aircraft landed approximately one mile from the airport. During the ground roll, it struck and rolled through a barbed wire fence, sustaining damage to the airframe. The pilot managed to bring the aircraft to a stop without further incident.
The investigation
A post-accident examination of the aircraft revealed significant mechanical discrepancies. Investigators found that a retaining nut was missing from a clamp located near two mating surfaces of the exhaust system, specifically in the vicinity of the number six cylinder.
This missing hardware allowed hot exhaust gases to escape the sealed system. These gases burned through a vacuum hose and extensively damaged multiple wires within the ignition system. The damage to the ignition wiring is consistent with the reported loss of engine power. Records indicated that the aircraft had been flown for 176 hours since the last engine and airframe inspection, suggesting that maintenance intervals may have played a role in the failure of the clamp or the wear on the components.