The flight instructor reported that, during preparation for the pilot's helicopter commercial check ride, they were going to practice autorotation procedures. He added that, during the second autorotation, he saw that the rotor RPM had dropped significantly, and the pilot was pulling up on the collective. He immediately took over command of the flight controls and attempted to lower the collective. Subsequently, the helicopter landed hard, bounced, yawed right, bounced again, and came to rest on the right side of the runway.

The helicopter sustained substantial damage to the tailboom.

The flight instructor reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation.