Incident Overview
A Bell 206B helicopter was engaged in transporting supplies between two mountain sites using a cargo net attached directly to the cargo hook, without a long line. The sling loads consisted of steel angle iron that was bagged, secured with velcro, and placed into the net. After delivering the fourth load, the pilot lifted off with only an empty bag remaining inside the net.
Flight Manual Guidance
The Bell 206B rotorcraft flight manual, in the supplement for external loading, states: "Control movements should be made smoothly and kept to a minimum to prevent oscillation of sling load."
Witness Account
According to a witness, as the helicopter departed, the net "floated very close to the propeller [tail rotor], then floated back down." The net then swung back up and impacted the tail rotor, cutting the cargo net and releasing the bag.
Pilot Actions
The pilot heard noise and "thumping" sounds, accompanied by vibrations and yawing, and realized that a tail rotor strike had occurred. The pilot entered an autorotation at "25 miles per hour and 200 feet" above a timbered slope. A small, sloped clearing was selected as a landing zone.
Accident Outcome
Upon touchdown, the helicopter rolled over, coming to rest on its right side.