On May 13, 1998, at 1810 eastern standard time (est), a Read Rotorway Executive 90, homebuilt helicopter, N4561C, operated by a commercial pilot, sustained substantial damage when maneuvering during initial hover, the helicopter's right transport wheel and skid caught on the concrete ramp, at Porter County Municipal Airport, Valparaiso, Indiana. The helicopter subsequently rolled over and impacted on the ramp. Visual meteorological conditions prevailed at the time of the accident. The local, personal flight was being conducted under 14 CFR Part 91. The pilot reported no injuries. In his written statement, the pilot said that he pushed the helicopter out of the hangar, preflighted it, started it, and warmed it up to operating minimums. "At light-on-the-skids point, all seemed fine." The pilot said that he lifted off of the ground to an approximate height of 12 inches. That is when he heard a "clunk" from behind him. The pilot said that he thought that something might have gone through the tail rotor, so he turned the helicopter to the left 180-degrees. Seeing nothing, the pilot decided to set down. At that point, the helicopter pitched over on it's right side. The pilot said that he "neglected to remove the transport wheels" before flight. A Federal Aviation Administration (FAA) inspector examined the helicopter in the pilot's hangar at Porter County Municipal Airport. Both main rotor blades showed chordwise scratches at approximately mid-span. The outboard tips of both rotor blades were curled upward. The fuselage was bent upward and wrinkled. The cockpit windscreen was broken out. The cockpit interior remained intact. No damage was observed to the seats, control panel, or helicopter controls. The right fin on the tail boom was scraped. The left fin was broken off. The tail rotor showed no damage. The right transport wheel was attached to the right skid. The wheel was bent down and inward, and broken on the outboard side. The left transport wheel was attached to the left skid. The left transport wheel axle and fitting were bent downward approximately 45-degrees. Helicopter flight control continuity was confirmed. No anomalies were found in the engine, engine controls, or other helicopter systems.