On July 10, 1997, at 1545 central daylight time (CDT), a Piper PA-25-235A, N7050Z, operated by Mid-Continent Aircraft Corp., was substantially damaged when it lost power in cruise flight and impacted the terrain about 11 miles from O'Neil, Nebraska. The pilot was not injured. The 14 CFR Part 91 flight had departed Clark, South Dakota, on a ferry flight to Hayti, Missouri. Visual meteorological conditions prevailed at the time and no flight plan was filed. The pilot reported that he had topped off the 39 gallon fuel tank prior to the flight. The pilot reported that he had departed for Hyati, Missouri, at 1345 CDT. He reported the AWOS indicated the weather was clear. The winds were from 160 at 20 knots gusting to 27 knots. He reported flying at 1,000 feet above ground level. While en route he changed course to the west to avoid weather. He reported that after two hours of flight the engine PRM's dropped from 2,200 RPM's to 2,000 RPM's, and then to 1,500 RPM's. He set up an approach to a field which ran north to south until the engine RPM's dropped to 1,000 RPM's, and he determined he could not make his intended field. He turned right to the southwest and attempted to land. He reported that as he flared during touchdown a wind gust from the south (his left) lifted the left wing and the right wing struck the ground and the airplane cartwheeled. The airplane came to rest facing the south after cartwheeling 270 degrees. The pilot exited the airplane with no injuries. An Airworthiness Inspector from the Federal Aviation Administration examined the airplane and the accident site. He reported that the airplane did not have an operable fuel indication system. The fuel shutoff valve actuating cable was disconnected and the valve was frozen in the open position. He reported that a visual inspection disclosed a small amount of fuel in the carburetor float chamber and the firewall fuel strainer. There was no evidence of fuel in the fuel tank or lower fuselage cavity. He reported there was no evidence of fuel seepage at the crash site or stains on the fuselage where fuel could have seeped out. He reported that the Enviromental Protection Agency representative did not find any evidence of fuel or chemical seepage at the accident site. The Airworthiness Inspector reported that there was no evidence of propeller rotation at impact. The magnetos and carburetor were examined and no anomalies were found.