Primary finding
Probable cause
The student pilot’s unstabilized hover, which resulted in ground contact and a dynamic rollover. Contributing to the accident was the flight instructor’s delayed remedial action.
Investigator assessment
Analysis narrative
According to the flight instructor in the skid-equipped helicopter, he was providing hover instruction to his airplane-rated student about 3 ft above the ground. The instructor reported that he allowed the student to make the necessary flight control inputs as he guarded the controls. The area was level with 1-ft-tall weeds. The helicopter began to drift laterally and descend. The right skid contacted the weeds, and the helicopter rolled onto its right side. The instructor reported that "I was not quick enough in lowering the collective to prevent full rollover." The helicopter sustained substantial damage to the tailboom and engine mounts. Per the National Transportation Safety Board's Pilot Aircraft Accident Report, the instructor reported that the accident could have been prevented by instructing hover practice at a "higher altitude and away from obstacles that may serve as a pivot point leading to dynamic rollover." The flight instructor reported that there were no preaccident mechanical malfunctions or failures 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 providing hover instruction to his airplane rated student, about three feet above the ground. The instructor reported that he allowed the student to make the necessary flight control inputs, as he guarded the controls. The area was level, with 1ft tall weeds. The helicopter began to drift laterally and descend. The right skid contacted the weeds and the helicopter rolled onto its right-side. The instructor reported that, "I was not quick enough in lowering the collective to prevent full rollover." The helicopter sustained substantial damage to the tailboom and engine mounts. Per the National Transportation Safety Board's Pilot Aircraft Accident Report, the instructor reported that the accident could have been prevented by instructing hover practice at a, "higher altitude and away from obstacles that may serve as a pivot point leading to dynamic rollover." The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation.