Incident Overview
A helicopter conducting a practice autorotation in a field landed hard and rolled over, coming to rest on its left side. The flight, which included a certified flight instructor (CFI) and a student pilot, encountered light turbulence and lost approximately 100 feet of altitude before initiating the autorotation maneuver.
Sequence of Events
At about 200 feet above ground level (agl), the rotor rpm gauge indicated a drop, and the low rotor rpm warning horn sounded momentarily. The student pilot responded by lowering the collective, but the helicopter began to experience a high sink rate. The CFI attempted a power recovery to counteract the sink rate; however, the helicopter continued to sink, and the rotor rpm remained low.
When the helicopter was a few feet above the ground and still sinking, the CFI made the decision to level the helicopter and prepare for an impact. The skids made contact with forward sloping terrain in a straight and flat attitude. Following touchdown, the helicopter rolled forward and to the left, ultimately resting on its left side.
Pilot Observations
The CFI and student pilot expressed the belief that the abnormally high sink rate may have been caused by adverse wind conditions in the area. A routine aviation weather report (METAR) from Prescott Regional Airport (PRC), located approximately 10 miles away on a bearing of 035 degrees, reported winds at 5 knots, gusting to 17 knots.
Outcome
The helicopter sustained damage during the rollover. No further details about occupants or injuries were provided in the source.