On August 6, 2004, about 1400 Pacific daylight time, a Cessna TR182, N4657S, landed gear up at Zamperini Field, Torrance, California. The private pilot owned and operated the airplane under the provisions of 14 CFR Part 91. The pilot and passenger were not injured, and the airplane was substantially damaged. Visual meteorological conditions prevailed, and an instrument flight plan had been filed. The personal cross-country flight was destined for Carlsbad, California, and originated at Torrance about 1200. The pilot told the National Transportation Safety Board investigator that while en route to Carlsbad he heard a bang from under the airplane, and at the same time the gear up light on the instrument panel went out. He cycled the landing gear switch with no effect. He then pumped the manual landing gear handle with no effect. The gear down light did not illuminate. The pilot decided to return to Torrance, and after discussing the situation with the tower he landed with the nose gear down and the main gear about halfway down. Examination of the airplane revealed that a braided hydraulic line leading to the nose gear hydraulic actuator had separated and pulled out of its connector fitting. Red fluid was on the airplane's skin behind the nose gear. A review of the maintenance logbook revealed that the airplane had its annual inspection signed off on April 13, 2004. During that inspection one of the two nose gear hydraulic actuator lines had been replaced. The newly installed hydraulic line was not the one that failed. According to the manufacturer, the hydraulic hose for the nose gear is inspected "on condition" and replacement is at the discretion of the inspecting mechanic or the airplane owner.