Accident Summary
A student helicopter pilot was conducting a solo flight when she experienced an abnormal vibration and a rapid nose-left yaw, followed by a hard landing. The helicopter sustained substantial damage to the aft skid tube cross-member. The pilot was uninjured and exited the helicopter after shutting down the engine.
Flight History
The student pilot had been working on her private helicopter pilot certificate over an extended period. The helicopter's throttle governor had been operational during previous solo flights but failed months prior to the accident flight. She had flown the helicopter several times without the governor under the supervision of her instructor.
On the day of the accident, she completed three takeoffs and landings in the traffic pattern with the flight instructor. After the third landing, the instructor exited the helicopter and authorized the student to perform her third solo flight.
During the pre-takeoff checks, the student increased the throttle and, as she raised the collective pitch, felt an abnormal vibration. Despite the vibration, she decided to continue. She increased collective and applied left pedal, and the helicopter ascended, but the nose yawed rapidly to the left. The engine RPM increased, and she lowered the collective. The left skid contacted the ground hard, followed by the right skid. The student reduced power, shut down the engine, and exited the helicopter.
The student reported that several mechanical malfunctions had existed with the helicopter during previous flights.
Post-Accident Examination
Examination of the helicopter and the operator's maintenance logbooks revealed maintenance squawks that were incorrectly annotated. However, no mechanical malfunctions or failures were observed during the examination that would have prevented normal helicopter operation. The operator has since implemented a policy to document and clear all future maintenance squawks associated with their fleet helicopters.