Incident Overview
A certified flight instructor and a student pilot were conducting practice 180-degree autorotations in a helicopter. During the initial entry into the autorotation, the student maintained proper rotor rpm and airspeed. Approximately halfway through the 180-degree turn, the helicopter became nose-low and airspeed increased. As the helicopter transitioned through about three-quarters of the turn, the instructor took control and attempted to correct the airspeed. The instructor was unable to correct the situation, and the helicopter touched down hard in an open dirt field.
Post-Impact Sequence
Following the hard touchdown, the helicopter rolled over and came to rest on its left side. Examination of the helicopter revealed that the tail boom had separated from the fuselage, and the fuselage sustained structural damage.
Instructor's Report
The flight instructor reported that no mechanical malfunctions existed during the practice autorotation or the accident sequence.