Primary finding
Probable cause
the pilot's inadequate compensation for strong, gusty, shifting winds while hovering in ground effect. Factors include a sudden directional change and increase in velocity of the gusty wind conditions.
Investigator assessment
Analysis narrative
While in a low hover just prior to initiating taxi, the helicopter encountered a "severe wind" that lifted it further in the air and required the pilot to reverse his slightly left anti-torque input to a full right input. The pilot initially began to transition to forward flight, but changed his mind and "dropped" the collective in order to put the aircraft back on the ground. As he was attempting to land, the helicopter weathervaned into the wind and started drifting backwards toward the fuel island. The pilot then applied forward cyclic, but was unable to arrest the backwards drift in time to keep the tail boom from impacting the gas island light pole.
Source record
Factual narrative
On May 3, 2001, approximately 1715 mountain daylight time, a Schweizer 269D, N2061D, collided with a gas island light pole while hovering at Nampa Municipal Airport, Nampa, Idaho. The private pilot, who was the sole occupant, was not injured, but the aircraft, which was owned and operated by the pilot, sustained substantial damage. At the time of the accident, the aircraft was hovering over its parking location near the fuel island just prior to initiating taxi for a CFR Part 91 personal pleasure flight to Twin Falls, Idaho. The accident occurred in visual meteorological conditions. No flight plan had been filed. According to the pilot, he lifted off and was hovering about one foot above the ground while visually clearing the area prior to initiating his taxi to the runway. As he looked out to his right he noticed a "twirl" of dust and small trees that were "laying over." He also noticed that the wind sock seemed to be standing straight out. Soon thereafter the helicopter encountered a "severe wind" that, according to the pilot, lifted the aircraft six feet in the air, and required him to reverse his slightly left anti-torque pedal input to a full right input. His initial reaction was to transition to forward flight, but after initially starting to do so, he "dropped" the collective in an attempt to put the helicopter back on the ground. While he was trying to land, the aircraft weathervaned into the wind and started to drift backwards toward the fuel pump island. At that time, the pilot applied forward cyclic in order to stop the helicopter from moving backwards, but he was unable to arrest the drift prior to the tail boom impacting the fuel island light pole.