Accident Summary
A helicopter conducting 180-degree autorotations during training experienced an accident on the third autorotation. The certified flight instructor (CFI) and a private pilot undergoing instruction were on board. The accident occurred when the helicopter ran over a 3-foot drop off during a run-on landing and came to rest on its left side. The temperature at the time of the accident was 39 degrees Celsius.
Sequence of Events
According to the CFI, the entry and glide into the third autorotation were uneventful. During the flare portion, sufficient rotor revolutions per minute (rpm) were not produced, and the low rotor rpm light and horn activated. In response, the helicopter was leveled and a run-on landing was performed. The CFI stated that the helicopter was not over the intended hard surface for landing. During the attempted run-on landing, the helicopter ran over a 3-foot drop off, causing it to come to rest on its left side.
Findings
The CFI did not report any mechanical malfunctions with the helicopter. The accident occurred under visual conditions with a temperature of 39 degrees Celsius.