MCDONNELL DOUGLAS HELICOPTER 500N near Idaho Falls, ID — 2014-08-12

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 narrative

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.

Analysis

Primary failure mode

Loss of control

First missed decision gate

Pilot could have aborted takeoff to reassess conditions.

NTSB coding

• Loss of tail rotor effectiveness · Takeoff

Evidence available

• 6 docket documents

Docket documents6

• Aircraft Performance Worksheetform
• Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1form
• Release of Aircraft Wreckage, NTSB Form 6120.15form
• Statement of Party Representatives to NTSB Investigation - Boeing Helicopterinterview
• Statement of Party Representatives to NTSB Investigation - MD Helicopterinterview
• Boeing Helicopter and MD Helicopter Field Notesother

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