Introduction
A certified flight instructor (CFI) was providing dual instruction to a student pilot during an accident flight. The student had accumulated approximately 13 hours of total flying experience. The CFI was handling the controls at the time of the accident.
Sequence of Events
The CFI was demonstrating a landing approach over hilly terrain at an elevation of 2,500 feet mean sea level. The first approach to the intended landing site was uneventful. During the second approach, the low rotor rpm warning horn activated. According to the CFI's initial statement to the Federal Aviation Administration and the National Transportation Safety Board, he attempted to "milk collective and get it back" but was unsuccessful. The CFI opined that the wind direction may have changed, prompting him to redirect the helicopter's course into the wind. Despite these efforts, he was unable to regain rotor rpm and stop the descent. The helicopter subsequently impacted the field and rolled over.
Pilot Actions
The CFI reported that at the time of the accident, the helicopter was operating near its maximum certificated gross weight. The helicopter's out-of-ground-effect hover ceiling was approximately 3,000 feet, and the density altitude was approximately 3,200 feet.
Environmental Factors
The density altitude exceeded the out-of-ground-effect hover ceiling, indicating reduced performance capability. The terrain was hilly, and the approach was being conducted at 2,500 feet mean sea level.