N804DFRobinson Helicopter R44 II · 2006

The pilot of a skid-equipped helicopter reported that the night before the accident flight, he hover-taxied into a hangar because convective activity was approaching the airport and he did not have ground-handling equipment (wheels) to move the helicopter. The following morning, he attempted to hover-taxi out of the hangar for a positioning flight, but the main rotor blade struck the top of the hangar door when the helicopter was about ¾ of the way out of the hangar. Subsequently, the helicopter spun and rolled over onto its left side.

The main rotor and tail boom sustained substantial damage.

The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation.

The helicopter pilot reported that while flying at a low altitude and low airspeed, over tree-covered terrain, he made a steep left turn downwind, and the low rotor rpm horn sounded. He stated that he lowered the collective slightly and rolled on throttle, but the helicopter descended and impacted trees and terrain.

The pilot reported that he completed a damage assessment and flew the helicopter to his home airport without further incident. Substantial damage was sustained to the helicopter left aft fuselage frame assembly. The pilot reported that there were no mechanical malfunctions or anomalies prior to or during the flight that would have prevented normal helicopter operation.

Vortex Ring State (Commonly known as "settling with power")

FAA-H-8023-21A identifies, "A vortex ring state may be entered during any maneuver that places the main rotor in a condition of descending in a column of disturbed air and low forward airspeed. Airspeeds that are below translational lift airspeeds are within this region of susceptibility to settling with power aerodynamics (pg. 11-10)."

"Some of the situations that are conducive to a settling with power condition are: any hover above ground effect altitude, specifically attempting to hover OGE at altitudes above the hovering ceiling of the helicopter, attempting to hover OGE without maintaining precise altitude control, pinnacle or rooftop helipads when the wind is not aligned with the landing direction, and downwind and steep power approaches in which airspeed is permitted to drop below 10 knots depending on the type of helicopter (pg. 11-10)."

The commercial pilot was conducting a photo flight with himself and two passengers in the four seat helicopter. The helicopter had been in a zero airspeed out of ground effect hover at approximately 40 to 50 feet above the ground for about 15 seconds when the pilot applied power to begin a vertical climb. According to the pilot, he then suddenly and without warning lost directional control, the helicopter began to spin nose right, and his application of full left pedal had no effect. The pilot initiated an autorotation and the helicopter landed hard on rough rocky sloping terrain between several trees. The crash caused substantial damage to the fuselage and airframe when the left skid gear partially collapsed and penetrated into the left rear passenger cabin floor area. The upper pylon was noticeably bent and wrinkled, and both main rotor blades were damaged. An on-scene investigation by an FAA maintenance inspector confirmed continuity and no apparent damage to the flight controls. There was no post-crash fire and the pilot and front seat passenger reported no injuries, but the left rear seat passenger suffered minor injuries and had to be carried out of the aircraft. The pilot reported the surface winds were light and variable, visibility 10 statute miles with scattered clouds at 3,000 feet, a temperature of 88 degrees, and an altimeter setting of 30.01 inches of mercury.