What happened
The aircraft was operating at an altitude of 1000 feet mean sea level when the pilot observed oil pressure drop to zero. This loss of pressure resulted in immediate engine seizure. While attempting to reach a nearby field for an emergency landing, the aircraft collided with the tops of pine trees. The impact caused the aircraft to land gear-up on its floats.
The investigation
A post-accident examination of the engine was conducted to determine the mechanical cause of the failure. The inspection revealed that the number 4 connecting rod had failed. Further analysis showed evidence that the nut securing this rod had come loose and detached during operation.
Findings
The primary factor contributing to the accident was the mechanical failure of the number 4 connecting rod. The detachment of the securing nut led to catastrophic engine seizure, leaving the pilot with no power. The subsequent collision with tree tops occurred while the pilot was maneuvering for an emergency landing site. The aircraft sustained significant damage from the impact and the subsequent gear-up landing on floats.
Safety message
Regular inspection of engine components, particularly connecting rod nuts and securing hardware, is critical to preventing in-flight engine failures. Pilots should be aware that sudden oil pressure loss often indicates severe internal mechanical failure with little time for recovery.