Incident Overview
A pilot made an emergency landing after a total power loss. Prior to the complete loss of engine power, there were approximately four drops in manifold pressure. During the landing, the landing gear collapsed, resulting in damage that bent the engine mounts and both wing spars.
Investigation Findings
The subsequent investigation determined that a 100-hour inspection had been completed six days before the accident. The mechanic who performed the inspection apparently failed to ensure that the left crossover exhaust collection elbow tube was properly aligned and that its clamp was secured.
This misalignment and lack of secure clamping allowed exhaust gases to escape and generate excessive heat. The heat from the exhaust gases caused the lead from the ends of the 'P' leads to melt into the condensers of both magnetos, shorting them out and resulting in the total power loss.
Pilot Actions
The pilot had opportunities to land at airports short of his intended destination but chose to continue the flight despite the manifold pressure drops, ultimately leading to the emergency landing.
Conclusion
The accident was caused by improper maintenance during the 100-hour inspection, which led to an exhaust leak that damaged the magnetos and caused total power loss.