Accident Details
The pilot of an airplane was conducting an aerial observation flight during night visual meteorological conditions. While approaching the ridge tops of a mountain range from east to west at an altitude of about 800 to 1,000 feet above ground level, the airplane experienced an uncommanded roll into a 90-degree left bank. The pilot corrected the roll and regained the original heading. Shortly thereafter, the airplane encountered another gust and rolled to the right.
Sequence of Events
As the pilot was rolling back to level flight, he realized that the top of the hill was higher than his current altitude and remained in a right turn. During the turn, the ground became illuminated by the landing light, and the airplane subsequently impacted snow-covered mountainous terrain, coming to rest upright.
Damage and Examination
An examination of the airplane by the pilot revealed structural damage to both wings and the left horizontal stabilizer. The pilot reported no mechanical anomalies that would have precluded normal operation prior to the accident. The pilot estimated the wind at the time of the accident to be from the west at 20 to 30 knots.