Mcdonnell Douglas Helicopter 500N N18GH accident near Idaho Falls, Idaho

Probable cause

The pilot’s loss of helicopter control for reasons that could not be determined because postaccident examination of the helicopter did not reveal any mechanical malfunctions or failures that would have precluded normal operation.

NTSB analysis

The pilot reported that he initiated a vertical climb in the helicopter to clear trees and a residential structure. When the helicopter was about 90 ft above ground level, it banked left and immediately began to rotate. The pilot made control inputs but was unable to regain control of the helicopter, so he initiated an autorotation. Subsequently, the helicopter impacted the ground and rolled over onto its right side. Postaccident examination of the airframe and flight control system revealed no evidence of any preexisting mechanical malfunction that would have precluded normal operation. Postaccident weight and balance and performance calculations revealed that, at the time of the accident, the helicopter was within weight and balance and performance limitations for an out-of-ground-effect hover.

Text from the NTSB. Open the NTSB docket for WPR14LA341 for the full record.