Accident Sequence
Shortly after takeoff, immediately following landing gear retraction, the engine backfired and experienced a total loss of power. The pilot lowered the landing gear and executed a straight-ahead landing just off the runway. Upon touchdown, the aircraft bounced once and came to rest in a city park. The aircraft immediately caught fire. Both occupants escaped from the aircraft but sustained serious burns.
Investigation Findings
Post-accident inspection of the engine revealed evidence of overheating. All spark plugs exhibited heavy deposits of lead and oil. The spark plugs were not gapped consistently, and the electrodes were gray in color. Tests conducted on the plugs showed that the majority failed to fire at high manifold pressures. The density altitude at the time was approximately 10,000 feet MSL.
Pilot Statement
The pilot reported that during the engine run-up before departure, the engine ran rough, but leaning the mixture helped smooth its operation. The pilot stated that he adjusted the mixture to full rich for takeoff.