What happened
A private pilot with 199 hours of flight experience was operating a vintage tube and fabric airplane on a local flight originating from the pilot's private airstrip. Several individuals in the area reported observing the aircraft flying at a low altitude and slow airspeed several minutes before the accident. One witness observed the aircraft flying south at an altitude between 25 and 50 feet with an estimated maximum airspeed of 50 miles per hour. The pilot lost control of the airplane while maneuvering at a low altitude, leading to an impact that resulted in a post-impact fire. There were no injuries reported.
The investigation
An inspection of the aircraft at the accident site revealed that all major components remained present. The fuel lever was found in the "on" position, and continuity to all flight controls was established. While the engine sustained damage from impact and fire, the propeller remained bolted to the prop flange, though the flange was bent, creating an angle between the crankshaft and the propeller.
Upon examination of the engine, both the left and right magnetos were found to be heat and fire damaged; manual rotation of the magnetos produced no spark. The engine was rotated by hand, confirming thumb compression on each cylinder and continuity through the motor to the accessory section. Examination of the bottom sparkplugs showed they were dark gray in color and worn. No pre-impact abnormalities were identified within the engine, cylinder assemblies, or engine components.
Findings
Toxicological testing of the pilot's blood revealed the presence of tetrahydrocannabinol (THC) and tetrahydrocannabinol carboxylic acid at levels consistent with very recent use.