Overview
The evening before the accident, the pilot introduced a mixture of hydraulic fluid and lacquer thinner into the engine in an attempt to free stuck valves. The following morning, he taxied the airplane to the grass runway on the airpark where he resided. During a lengthy runup, the airplane unintentionally became airborne. Shortly thereafter, the airplane rolled to the right, struck trees, and impacted the ground.
Pilot Medical Background
The pilot had been treated for several ongoing medical issues. He did not hold a current medical certificate. His conditions included high blood pressure, recent evidence of previous asymptomatic strokes, and persistent knee pain following a right knee replacement. He was also taking a blood thinner.
Potential Scenario
According to the investigation, the pilot may have been unable to maintain control of the aircraft during the engine run-up due to knee pain. Alternatively, he may have suffered a sudden hemorrhagic (bleeding) stroke into the brain. Such a stroke was considered considerably more likely given his age, high blood pressure, and continued use of a blood thinner.