Incident Overview
Approximately 1.5 hours into an introductory instructional flight focused on night vision goggles (NVG) operation, the pilot and flight instructor returned to the airport to conduct autorotation practice from a hover. The helicopter was established in a 3-foot hover when the flight instructor moved the fuel flow control lever toward the idle cutoff position, initiating the maneuver.
Sequence of Events
In response to the instructor's action, the pilot increased collective pitch. This caused the helicopter to ascend, and consequently, the rotor rpm decayed. The flight instructor attempted to apply corrective inputs, but the pilot physically resisted those efforts. The helicopter then descended rapidly to the ground, resulting in substantial damage to the tailboom.
Pilot Observations
The pilot reported that during the maneuver, he misjudged the helicopter's height above ground, attributing this to the decreased peripheral vision provided by the NVGs. This was the pilot's first flight operating with NVGs.
Damage
The accident resulted in substantial damage to the helicopter's tailboom. No other damage was reported.
Probable Cause
No probable cause was stated in the source.