Primary finding
Probable cause
The flight instructor's failure to maintain sufficient altitude over uneven terrain during a hover taxi, which resulted in ground contact and a subsequent dynamic rollover.
Investigator assessment
Analysis narrative
According to the flight instructor in the skid-equipped helicopter, he was going to demonstrate a maneuver to his airplane-rated student. The instructor reported that he air taxied the helicopter to the departure end of the runway. He then slowed down the helicopter, and while turning and hover taxiing over the grassy area between the taxiway and the runway, the right skid's toe contacted the uneven ground. The helicopter pivoted around the toe and rolled onto its side. The helicopter sustained substantial damage to the fuselage and rotor systems. The instructor reported that there were no preimpact mechanical failures or malfunctions with the helicopter that would have precluded normal operation.
Source record
Factual narrative
According to the flight instructor in the skid-equipped helicopter, he was going to demonstrate a maneuver to his airplane rated student. The instructor reported that he air taxied the helicopter to the departure end of the runway. He then slowed the helicopter down and while turning and hover taxiing over the grass area between the taxiway and the runway, the toe of the right skid contacted the uneven ground. The helicopter pivoted around the toe and rolled onto its side. The helicopter sustained substantial damage to the fuselage and rotor systems. The pilot reported that there were no preimpact mechanical failures or malfunctions with the helicopter that would have precluded normal operation.