Accident Overview
A helicopter collided with terrain after experiencing a loss of antitorque control during a practice slope landing. The accident occurred during the third or fourth practice landing attempt, when the helicopter's skids were positioned such that the rear portions angled downward toward lower terrain.
Sequence of Events
As the student pilot configured the flight controls to remove the load off the rotor blades, the tail of the helicopter began to tip backwards. The certified flight instructor (CFI) took control of the helicopter and added power to prevent the tail rotor from striking the terrain. In response, the helicopter began to rotate to the right about its vertical axis. The CFI attempted to maintain level flight and counteract the spin by applying antitorque pedal input, but was unable to maintain control. After four or five revolutions to the right, the helicopter's right front section impacted the terrain.
Factors
The loss of antitorque control preceded the collision. The helicopter's configuration during the approach and the subsequent rotor loading changes likely contributed to the loss of control. The CFI's power addition to avoid a tail rotor strike may have exacerbated the rotation. No other factors are stated in the source.
Damage
The helicopter sustained damage upon impact with terrain, specifically to its right front section. The extent of damage and whether there were any injuries are not detailed in the source.