Accident Overview
A float-equipped airplane was in cruise flight at approximately 1,200 feet above ground level when the engine emitted a loud noise and lost partial power. The pilot maneuvered the airplane to land on a nearby lake, but during the approach, the engine lost total power. The airplane descended into an area of trees before reaching the lake, resulting in substantial damage to the wings, fuselage, and empennage.
Engine Examination
The operator reported that the engine had been overhauled (zero-timed) 31 hours before the accident. A postaccident examination of the engine revealed metal fragments and heavy gouging damage to the rotating components within the crankcase. The bottom portion (crankshaft end) of the n°1 linkrod and its respective bushing were missing from the n°1 linkpin. The oil sump contained metal debris consistent with heavily damaged remnants of these and other components. The n°2 cylinder barrel and linkrod and the n°3 linkrod showed deformation to the left, in the direction of engine rotation.
Failure Determination
Based on the damage observed in the engine, it is likely that the event that initiated the engine failure involved either the n°1 linkrod bushing or the bottom portion of the n°1 linkrod. However, the extensive damage to these components precluded determination of the failure mode.
Probable Cause
The official probable cause of the accident was the failure of the n°1 linkrod bushing or the bottom portion of the linkrod, which resulted in a total loss of engine power.