On April 8, 2009, about 1513 Pacific daylight time, a Beech A36TC, N333HP, landed with its landing gear retracted at the Roseburg Regional Airport, Roseburg, Oregon. The commercial certificated pilot owned and operated the airplane, and was not injured. The airplane was substantially damaged. Visual meteorological conditions prevailed, and no flight plan was filed. The personal flight was performed under the provisions of 14 Code of Federal Regulations Part 91, and it originated from the airport about 1508. The pilot reported that as he was approaching the airport for landing on the downwind leg, and completing the airplane's checklist, his attention was "focused outside the cockpit." The pilot stated that he "apparently forgot to lower [the airplane's] landing gear." An examination of the airplane by a Federal Aviation Administration (FAA) airworthiness inspector revealed that at least 5.5 feet of belly skin was damaged and was partially ground off to the rivet lines. Two belly ribs were broken. The damage also was evaluated by Hawker Beechcraft personnel who reported that in several locations "the underlying fuselage structure was abraded to the point where there [was] no remaining structure to attach the skin." The FAA coordinator reported that a major airframe repair would be required to restore airworthiness to the airplane's fuselage. In the pilot's National Transportation Safety Board "Pilot/Operator Aircraft Accident" report form, #6120.1, he indicated that during the flight he had not experienced any mechanical malfunction or failure with his airplane. The pilot did not report the date of his last flight review or the date of the airplane's last annual inspection.