Incident Overview
A helicopter pilot and passenger were inbound for landing when the pilot requested permission to perform an autorotation, which was granted. During the maneuver, the pilot perceived that the helicopter would not reach the runway and attempted to add power. However, the engine failed to respond.
Sequence of Events
As the helicopter descended, the tail stinger contacted the ground, causing the tail boom to separate from the main fuselage. The pilot then pulled collective pitch, which momentarily lifted the helicopter before it entered a violent right spin. The pilot managed to maintain a level attitude as the helicopter touched down hard. After the rotor system stopped, both occupants exited the aircraft safely.
Pilot Comments
In post-flight remarks, the pilot noted that he should have applied carburetor heat before the extended idle period during the autorotation. The ambient temperature and dew point were within the range considered conducive to serious carburetor icing during glide power operations.