What happened
While operating at approximately 1,200 feet above the ground, a float-equipped aircraft experienced a sudden loud noise followed by a partial loss of engine power. In response to the mechanical issue, the pilot attempted to execute an emergency landing on a nearby lake. During the descent, the engine suffered a complete loss of power. The aircraft subsequently struck a group of trees before reaching the water's surface. The impact resulted in substantial damage to the fuselage, wings, and empennage.
Findings
An inspection of the engine, which had undergone a zero-time overhaul only 31 hours prior to the incident, uncovered significant internal destruction. Investigators discovered metal fragments and severe gouging on the rotating parts inside the crankcase. Specifically, the bottom section of the number one linkrod and its associated bushing were absent from the number one linkpin. Additionally, metal debris found in the oil sump was consistent with the destruction of these parts.
Further examination showed that the number two cylinder barrel and linkrod, along with the number three linkrod, had been deformed in the direction of engine rotation. The investigation concluded that the failure of the number one linkrod or its bushing likely initiated the engine failure, though the severity of the internal damage prevented a more specific determination of the exact failure mechanism.