On November 30, 1999, about 1205 eastern standard time, a Cessna 182RG, N1818R, registered to a private individual, operating as a Title 14 CFR Part 91 personal flight, made a gear-up landing at Jacksonville International Airport, Jacksonville, Florida. Visual meteorological conditions prevailed and no flight plan was filed. The airplane received substantial damage and the private-rated pilot, the sole occupant, was not injured. The flight originated from the same airport about 15 minutes before the accident. According to the pilot, he intended to fly the airplane around the landing traffic pattern to warm the crankcase oil in preparation for an oil change and annual inspection, and forgot to lower the landing gear for landing. A postaccident check of the airplane revealed the main landing gear bulkheads were minimally ground down by the slide on the concrete runway, and the gear unsafe warning horn circuit was inoperative, although the gear up amber position lights operated normally. According to an FAA inspector, the pilot stated to him that he failed to extend the landing gear. The inspector confirmed that the dual warning horn assembly, (stall and gear-up with throttle at idle) was found to be inoperative, postaccident.