On July 14, 2005, approximately 0730 mountain daylight time, a Bellanca 8GCBC, N5043N, was substantially damaged when it struck a portable helipad while taxiing after landing at the Denver Centennial Airport (APA), Englewood, Colorado. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under the provisions of Title 14 Code of Federal Regulations, Part 91 without a flight plan. The pilot and passenger were not injured . The local flight originated at Boulder, Colorado, approximately 0700. According to the pilot, he landed on runway 17L and turned off onto taxiway A4. He said he was directed by the control tower to cross taxiway "A" straight onto the ramp. The pilot said that he commutes by airplane each day to APA and has a permanent tie-down spot in the "close-in" area of the "TAC Air" ramp. He said that there were several routes he could take to get to his tie-down spot, involving taxing north through an open area, west and parallel to taxiway "A." The pilot said that there are usually several helicopter dollies there. An Tac Air employee was moving a jet in the western-most portion of the open area, so the pilot chose to taxi north through east portion of the open area that was next to the close-in area. The pilot said he was taxiing at a normal "fast walking pace" with engine power set at 1,000 rpm. As he approached the north side of the open area, the pilot said he heard a loud banging noise and felt the airplane pitch over on its nose. The pilot said the tires had contacted a helicopter dolly, "causing a sudden stop and pitch-over." The pitch-over caused the propeller to strike the dolly causing the propeller and engine to suddenly stop. An examination of the airplane showed the bottom aft part of the Fiberglas cowling crushed and broken upward approximately 2 inches. The attach points to the left and right landing gear struts were bent aft. The left gear attach point was also fractured. The fuselage frame structure and skin in the area of the landing gear strut attach points, cowling, and bottom forward fuselage were bent upward and aft. The propeller blades showed torsional and aft bending, and chordwise scratches. An examination of the airplane's systems revealed no anomalies. The helicopter dolly was a 10-by-10 foot square, 1 foot high, wooden deck. The platform had a metal frame with castered wheels, foot pads, and a "Y-shaped" tow bar. The deck was a natural wood color. The frame around the deck was painted white. The dolly was located at the northwest corner of the TAC Air ramp abeam the A3 taxiway, and approximately 18 feet south of the west to east running yellow taxi stripe that leads from taxiway "A" to the ramp. In his statement, the pilot said that while taxiing, he was actively scanning for conflicts and noting all aircraft and vehicles in the vicinity. The pilot said he never saw the dolly until the airplane struck it. When questioned about his airplane, the pilot stated, "... it has decent forward visibility when in the three-point configuration and normally does not require weaving to be able to see objects off the nose. At only one foot high, completely flat, and neutral in color, the object (helicopter dolly) is quite difficult to spot. The dolly was placed in a common movement area." According to the Federal Aviation Administration (FAA), the area through which the pilot was taxiing was considered a non-movement area. According to the 2005 Aeronautical Information Manual, non-movement areas are taxiways and apron (ramp) areas not under control of air traffic. Aircraft clearance from other aircraft or objects while taxiing in these areas is the responsibility of the pilot. Additionally, FAA inspectors observed a faded "NO TAXI" marking on the non-movement area approximately 30 feet south of the helicopter dolly. The marking was located such that the pilot would have taxied over it before striking the helicopter dolly.