Incident Summary
A Robinson R-22 helicopter suffered an engine shutdown in flight after the pilot mistakenly pulled the mixture control knob while attempting to adjust the trim. The helicopter struck overhead powerlines and an automobile during an autorotation landing, resulting in damage to the windscreen, main rotor blades, and tailboom.
Sequence of Events
According to the pilot, after reaching cruising altitude, he reached for the trim adjustment knob but inadvertently pulled the mixture control knob, causing the engine to stop. The pilot immediately lowered the collective lever and entered an autorotation. He attempted to restart the engine using the throttle and starter, but did not advance the mixture control from the idle cut off position. During the landing flare, the windscreen contacted powerlines, and the helicopter then struck an automobile on the roadway.
Aircraft Information
The helicopter involved was a Robinson R-22. The pilot operating handbook for this model notes that if the mixture control is inadvertently pulled in flight, engine stoppage will result, and advises pilots to reach around the left side of the cyclic to actuate lateral trim to avoid pulling the wrong control. The accident caused damage to the windscreen, main rotor blades, and tailboom.