Incident Summary
A helicopter engaged in pinnacle landing training experienced an abnormal event that led to it sliding down a slope. The aircraft was being operated by a dual student under the supervision of a certified flight instructor (CFI). According to the CFI's account, the helicopter began to vibrate and moved sideways during the landing maneuver. The instructor responded by increasing power. However, by the time the helicopter reached the edge of the landing area, the rotor rpm had decreased to a point where repositioning was not possible.
Sequence of Events
The CFI reported that he then performed a pedal turn to orient the tail of the helicopter downhill. He subsequently lowered the collective control and rolled off the throttle. Following these actions, the helicopter slid approximately 300 feet from the top of the hill down a 30-degree slope. During the slide, the main rotor blades made contact with the ground. Despite this, the helicopter remained upright and did not roll over.
Aircraft and Crew Information
No specific details regarding the helicopter type or registration were provided in the source. The crew consisted of a CFI and a dual student. The source stated that there were no mechanical malfunctions with the aircraft prior to the accident.
Probable Cause
The source did not identify a probable cause for the incident.