On April 1, 2003, at approximately 1645 mountain standard time, a Piper PA-18A-150, N6883B, was substantially damaged when it impacted terrain while maneuvering approximately 31 miles southwest of Newcastle, Wyoming. The private pilot and passenger sustained serious injuries. Visual meteorological conditions prevailed for the local flight being conducted under the provisions of Title 14 CFR Part 91. No flight plan had been filed for the flight that had originated approximately 1500. The pilot did not submit an accident report due to personal injuries and extended hospitalization. According to the Federal Aviation Administration (FAA) inspector, the pilot was "checking" cattle. He was reversing course to the right, to check on a newborn calf, when the right wing tip impacted terrain. Subsequently, the airplane cartwheeled, coming to rest inverted. The right wing was bent and wrinkled, and its spar was broken. the fuselage was crushed, and the empennage was wrinkled and bent. FAA records show the pilot's last medical was dated February 1, 1994. Documentation for the pilot's biennial flight review or the airplane's annual inspection were not found.