Accident Overview
The aircraft's engine lost power due to severe detonation shortly after takeoff. During the ensuing forced landing on a road, the airplane collided with trees and the road median.
Pilot Actions
The pilot stated that he had leaned the mixture during climb to 30 gallons per hour because the fuel flow gauge was indicating a 'red line of about 35 gallons per hour.' During the climb, the engine RPM started to 'over speed.' The pilot attempted to reduce engine RPM with the propeller control then subsequently with the throttle; however, the engine 'quit.'
Post-Accident Examination
Examination of the engine revealed that all cylinders showed signs of severe overheating and characteristics of lean mixture operation and detonation. According to the performance charts, the fuel flow should have been set to approximately 20.5 gallons per hour. The complete engine fuel system was bench checked, revealing no anomalies that would have prevented normal operation of the engine. Post-accident testing of the fuel flow gauge revealed that the gauge operated correctly and indicated fuel flow properly.