Primary finding
Probable cause
The student pilot’s rapid lowering of the collective, which resulted in a hard landing.
Investigator assessment
Analysis narrative
The flight instructor reported that, during the landing from a hover, he and the student pilot were both on the controls, with the student manipulating the controls. He added that, when the helicopter was about 8" above the ground, the student lowered the collective rapidly. Subsequently, the helicopter landed hard, the student immediately raised the collective to re-establish a hover, and the instructor took the flight controls and landed without further incident. A postaccident examination revealed the helicopter sustained substantial damage to the tail boom. The flight instructor reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation.
Source record
Factual narrative
The flight instructor reported that, during the landing from a hover, he and the student pilot were both on the controls, with the student manipulating the controls. He added that, when the helicopter was about 8" above the ground, the student lowered the collective rapidly. Subsequently, the helicopter landed hard, the student immediately raised the collective to re-establish a hover, and the instructor took the flight controls and landed without further incident. A post-accident examination revealed the helicopter sustained substantial damage to the tail boom. The flight instructor reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation.