Accident Summary
During an instructional flight focused on simulated emergency governor operations, a single-engine helicopter executed a hard landing in a near level attitude with a slight tail-low orientation. The landing gear skids collapsed upon impact, causing the lower vertical fin and tail rotor assembly to contact the ground. This interaction buckled the tail boom at its forward attachment points. The helicopter then slid approximately 250 feet on its fuselage before coming to rest upright. The crew performed an emergency engine shutdown and egressed from the aircraft without assistance.
Examination Findings
The wreckage was recovered to the operator's secured facilities for further examination. Investigators tested the throttle twist grip by simulating actions taken during the training flight. The governor was cycled from "auto" to "manual" mode for two minutes and back to "auto" for three minutes, repeated several times, to determine if a restriction in manual throttle operation would occur. After multiple cycles, the solenoid that retracts to allow manual throttle manipulation failed to fully retract due to heat generated during activation, creating a restriction.
Seat Analysis
Examination of the crash-attenuating seats documented that the left front seat fully attenuated during the crash sequence, while the right front seat showed no evidence of attenuation. The seats were shipped to the manufacturer's facilities in France for further testing. Analysis revealed that the seats met specifications, and evidence on the right seat indicated that attenuation had initiated but did not sustain sufficient forces to fully stroke.