On June 14, 2018, about 1445 mountain daylight time, a Rockwell International 112TC airplane, N4954W, was substantially damaged during a forced landing near Cheyenne Regional Airport/Jerry Olson Field (KCYS), Cheyenne, Wyoming. The pilot and passenger were not injured. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no Federal Aviation Administration (FAA) flight plan was filed for the flight. The airplane departed Skyview Airpark (WY05), Cheyenne, Wyoming, and was en route to KCYS at the time of the accident. According to the written statement provided by the pilot, he preflighted the airplane and confirmed about ¼ tank of fuel for each wing fuel tank, using the indication on the fuel gauges and knowledge from fuel burn and the previous day's flight. He did not have a fuel stick calibrated for the airplane. No contamination was noted in the fuel sump samples. The engine started and ran during the engine runup without issues. The entire flight was conducted with the fuel selector valve selected to BOTH. About 5 miles from KCYS, the engine rpms dropped, and the pilot adjusted the mixture and throttle setting which resulted in an increase in engine power. About a minute later, the engine rpms decreased again, and the pilot went through the checklist to restore power and requested to land straight in at KCYS. The power increased for 10 seconds and then went to idle. During a forced landing to the field, just east of the approach end to runway 27, the outboard portion of the right wing impacted the ground and separated, and the empennage and fuselage were bent and wrinkled. Measurable fuel was documented in the left-wing fuel tank and trace fuel was documented in the fuel lines for the right-wing fuel tank. The right-wing fuel line was impact separated and the right-wing fuel tank was empty. An examination of the airframe, engine, and fuel system, conducted by the National Transportation Safety Board, revealed no preaccident mechanical anomalies that would have precluded normal operations.