On July 2, 1998, approximately 1000 mountain daylight time, N8933D, a Piper PA-20-160 (converted from a PA-22-160), was substantially damaged when it collided with terrain during landing at Kemmerer, Wyoming. The private pilot, the sole occupant aboard, was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight being operated under Title 14 CFR Part 91. The flight originated at a private airstrip at Farson, Wyoming, approximately 0930. In a telephone interview with the pilot, he said he "let the airplane get ahead" of him. He landed in light and variable winds and during the rollout, the airplane began "fishtailing" and ground looped. According to the pilot's accident report, the airplane touched down on runway 34 and the tail veered to the left. He responded with left rudder input. The tail then swerved to the right and he responded with full right rudder and brake and directional control was lost. The pilot indicated he had 9 hours in airplane make and model. The pilot did not immediately report the accident. According to the sheriff, he noticed the damaged airplane during a routine patrol. When an FAA inspector went to investigate, the airplane was gone. After the pilot was located by the FAA, the pilot contacted NTSB on July 13. He was asked to explain why the accident was not reported expeditiously to the nearest NTSB office. He did not answer the question.