On January 27, 1999, at 1519 mountain standard time, a Piper PA- 18-150, N7188Z, operated by a private pilot, collided with powerlines and the terrain, about eight miles southwest of Hyannis, Nebraska. The pilot reported minor injuries. The airplane was substantially damaged. The 14 CFR Part 91 flight was operating in visual meteorological conditions without a flight plan. The flight originated from Hyannis, Nebraska. The pilot reported he was checking the pastures when he saw someone who he recognized fishing. He reported he entered a left turn and was looking at the person holding up fish when the airplane contacted the top of two transmission lines. The airplane then descended to impact with the terrain. One end of the section of wire contacted was suspended from a pole that sits on a hill. The other end is on flat terrain. The span of transmission line that was contacted was approximately 100 feet long. The pilot reported he was aware of the powerline, but that he had forgotten about it.