Wind is defined by Webster’s dictionary as a strong current of air. Although simple in definition, the affects of wind on a helicopter can be profound. To a pilot who clearly understands this, wind can be very helpful. Yet, helicopter pilots sometimes underestimate the risks of flying in gusty wind conditions.
On March 27, 2002, the pilot of a Hughes 269 helicopter lost control while hovering at the Fort Collins Downtown Airport. The flight instructor reported that the wind was about 2 knots at takeoff, but forecasted to be gusty in the afternoon. While hovering at about 3 ft with the student pilot at the controls, the helicopter encountered a very strong gust and began to wobble. The instructor took control of the helicopter and climbed to about 15 ft when another gust hit the helicopter, turning it sideways and then downwind. The instructor stated he was attempting to get it on the ground, but the wind continued to drive the helicopter forward with excessive nose-over tendency. With the tail rotor into the wind, creating a high power demand and limited tail-rotor authority, the helicopter skipped along the dirt two or three times. The helicopter traveled forward 180-200 ft. The right strut failed, and the helicopter rolled over on its right side.
The instructor reported that he thought the wind was gusting to 60 knots at the time of the accident. The reported weather at the Fort Collins-Loveland Municipal Airport, 8 nm south of the accident site, was wind from 260 deg at 13 knots, gusting to 25.
Extra care should be taken when sitting on the ground with less than 100% rotor rpm in windy conditions. Wind can affect the flexing of a rotor blade at low rpm much more than at normal speed. An Enstrom 280FX helicopter was substantially damaged when the main rotor blades struck the tail boom while sitting on the ground. In an interview with the NTSB, the pilot stated he landed in a corn field and got out of the helicopter while the rotors were still under power. Then, he said a gust appeared and the main rotor severed the tail boom.
It should go without saying that leaving the pilot station of a helicopter with power still applied to the rotor system is just a really bad idea under any circumstances.