No fatalities

15 Jan 2011: BELL 206B3 — Skymission LLC — Three Forks, MT

Three Forks, MT, United States

On 15 Jan 2011, a BELL 206B3 operated by Skymission LLC was involved in an aviation accident near Three Forks, MT. No fatalities were reported. Investigators recorded the probable cause as: The pilot’s inadequate use of throttle during the practice autorotation that resulted in a hard landing. This summary draws on records from NTSB; 1 related events involving the same aircraft type or operator are linked below.

SourcesNTSBPrimary reportUpdated 1778583330Data APIEditorial standards

A helicopter sustained substantial damage during a practice autorotation when the pilot did not add power at the bottom of the descent, resulting in a hard landing and tail rotor separation.

Accident Overview

A pilot practicing autorotation maneuvers experienced a hard landing resulting in substantial damage to the helicopter. The pilot had entered a straight-in practice autorotation, pointing the helicopter into the wind at 800 feet above ground level near midfield and above the runway. During the descent, the pilot monitored main rotor rpm and airspeed, which remained within normal ranges.

Maneuver and Descent

The pilot rolled the throttle to flight idle, lowered the collective, and gently flared the nose to set appropriate main rotor rpm and airspeed. At the bottom of the descent, the pilot flared slightly higher than usual to ensure tail boom clearance for a planned power recovery. However, the pilot stated he did not add power at that point.

Impact and Damage

Due to inadequate rotor inertia to dampen the landing, the helicopter hit hard despite full collective deflection. The main rotor blade contacted the tail boom, causing the aft portion of the tail boom and tail rotor to separate. The skids were also damaged. The pilot performed an emergency shutdown, closing the throttle and switching off the battery, generator, and fuel valve. After exiting, he secured the battery.

Post-Accident Actions

The pilot's actions after landing included an emergency shutdown and securing the battery. The helicopter sustained substantial damage but no injuries were reported.

Contributing factors

Incorrect use/operationPilot