Accident Overview
On August 15, 2008, at 0700 central daylight time, a Hiller UH-12E helicopter collided with terrain after contacting unmarked power lines during an aerial application flight near Cokato, Minnesota. The pilot was not injured, and the helicopter was substantially damaged. The flight was operating under Title 14 Code of Federal Regulations Part 137. Visual meteorological conditions prevailed, and no flight plan was filed. The local flight originated just prior to the accident.
Flight Details
The pilot reported that he made three passes over the fields intended for spraying. During these passes, he noticed a power line pole with a transformer cover and what appeared to be a wire covering running up the pole. Based on this observation, the pilot concluded that the power lines in the area were buried. He then landed and loaded the chemicals. After taking off with the load, the pilot flew one additional pass to look for power lines but did not see any.
Pilot Report
While conducting the first swath run, the helicopter contacted power lines. The helicopter initially pitched nose up and to the right. The pilot stated that he pushed the nose down and to the left, but the power lines wrapped around the control tubes and tail rotor. The helicopter then entered a descending spin. The pilot reported that he pulled back to flatten the descent just prior to the helicopter contacting the ground.
Impact and Damage
The helicopter sustained substantial damage due to the collision with terrain following the power line strike. The pilot was not injured. The accident occurred at approximately 0700 central daylight time in Cokato, Minnesota.