What happened
The Piper J-3 Cub was operating in a cruise phase of flight when it experienced an unexpected loss of engine power. Witnesses observed the aircraft flying at an altitude described as just above the tree line before the incident occurred. Following the power failure, the aircraft impacted the ground and was destroyed. The pilot sustained fatal injuries in the crash.
The investigation
A physical examination of the aircraft's engine was conducted to determine the cause of the power loss. Inspectors discovered that the fuel drain valve on the fuel gascolator was missing. Furthermore, no evidence of fuel was found on the aircraft during the post-accident analysis, indicating a complete lack of fuel supply to the engine.
Findings
The absence of the fuel drain valve allowed fuel to escape from the system, leading to fuel exhaustion. This mechanical failure directly resulted in the loss of power and the subsequent crash. The pilot was fatally injured in the accident.