Bell 206B3 N78BR accident near Three Forks, Montana

Probable cause

The pilot’s inadequate use of throttle during the practice autorotation that resulted in a hard landing.

NTSB analysis

The pilot practiced several maneuvers and then entered a straight-in practice autorotation. He pointed the helicopter into the wind at 800 feet above ground level near midfield and above the runway. He reduced the throttle to flight idle and lowered the collective while gently flaring the nose of the helicopter to set up the appropriate main rotor rpm and airspeed. He reported that he monitored those parameters carefully during the descent and noted that they remained well within the normal range. At the bottom of the descent, the pilot flared a little high to allow a margin of safety for tail boom clearance as he was planning a power recovery from the autorotation. The pilot stated that he did not add power at that point and that there was inadequate rotor inertia to dampen the landing, even though he applied full collective deflection. The helicopter hit hard and sustained substantial damage. The aft portion of the tail boom and tail rotor separated due to a main rotor blade contact and the skids were damaged.

Text from the NTSB. Open the NTSB docket for WPR11CA101 for the full record.