Accident Overview
An experimental aircraft experienced a complete loss of engine power shortly after departing from runway 30. The aircraft had climbed to approximately 400 feet above ground level when the power loss occurred. The pilot initiated a turn toward an empty field with the intention of performing an engine-out forced landing. However, the aircraft was unable to reach the selected field and instead impacted an orchard of young apple trees just short of the intended landing area.
Post-Accident Inspection
A thorough inspection of the aircraft after the accident identified the cause of the engine power loss. The screw that holds the valve retaining faceplate on the Airflow Performance Purge Valve Assembly had come loose, allowing the valve mechanism to separate from its housing. Further examination revealed that the retaining screw had not been re-safetied after the aircraft builder removed the manufacturer-installed safety wire. The builder had removed the safety wire in order to change the angular configuration of the purge valve/flow divider assembly.
Manual Guidance
A review of the Airflow Performance Installation and Service Manual disclosed a narrative section stating that if removal of the valve is necessary, the purge valve stop/faceplate screw must be re-safetied. The absence of this safety measure allowed the screw to loosen during flight, leading to the engine failure.