N921ES

According to the pilot, he was hover taxiing the helicopter in a confined area, after refueling. He reported there was a large tree to the southwest of his position and a light pole to northeast of his position. He recalled that he began to taxi to the northwest; away from the light pole, but "a significant left quartering wind" about 9 knots gave him "a hard time controlling the tail". He reported that he did not feel that he could turn the nose into the wind in the confined area and decided to climb vertically to avoid obstacles. He reported that he ascended, encountered a wind gust, and the tailboom yawed to the right and struck the light pole. The helicopter descended, impacted the ground, and came to rest on its left side. The helicopter sustained substantial damage to the fuselage, the main and tail rotor systems.

The pilot reported that there were not any mechanical anomalies or malfunctions with any portion of the helicopter that would have prevented normal flight operations.

The nearest weather reporting station was two miles north-northwest. The meteorological aerodrome report about the time of the accident reported the wind was out of 160 degrees true at 11 knots.

FAA-8083-21A, Chap. 11-20 para. 2 states:

Weathercock Stability (120–240°)

In this region, the helicopter attempts to weathervane, or weathercock, its nose into the relative wind. Unless a resisting pedal input is made, the helicopter starts a slow, uncommanded turn either to the right or left, depending upon the wind direction. If the pilot allows a right yaw rate to develop and the tail of the helicopter moves into this region, the yaw rate can accelerate rapidly. In order to avoid the onset of LTE in this downwind condition, it is imperative to maintain positive control of the yaw rate and devote full attention to flying the helicopter.