On July 20, 2011, about 1325 central daylight time, a Cessna T210L, N2056S, experienced a collapsed right main landing gear during landing at Columbia Regional Airport (COU), Columbia, Missouri. The private pilot was uninjured. The airplane sustained substantial damage to the horizontal stabilizer. The airplane was registered to and operated by Atlatl LLC under the provisions of 14 Code of Federal Regulations Part 91 as a business flight. Visual meteorological conditions prevailed and a flight plan had not been filed for the flight destined for COU. The pilot stated that while on a visual approach to runway 20 (6,501 feet by 150 feet, concrete) and about 3 miles from COU, he moved the landing gear handle to the down position. The landing gear extended, but the landing gear indicator lights did not indicate that the landing gear was locked in the down position and he could hear the landing gear hydraulic pump running. He then cycled the gear two times, but the landing gear still would not lock into the down position. He cycled the landing gear six more times, but the landing gear did not lock down and the hydraulic pump stopped making a sound. He then extended the emergency gear pump handle and pumped it 75-100 times, which became very stiff. He flew over the airport so that air traffic control personnel could observe the landing gear, which they reported as being extended; however, the cockpit indication was indicating that the landing gear was not locked down. During final approach for landing on runway 20, he pumped the emergency gear pump handle "many more times," but the landing gear still did not lock down. During touchdown, the right main landing gear collapsed. The airplane departed the runway surface and stopped near the intersection of taxiway A2 and runway 20. The airplane struck, and broke off from its base, the hold short sign at taxiway A2. According to the Federal Aviation Administration, postaccident repair, by a maintenance facility other than the one that performed the airplane's last annual inspection, indicated that a lack of lubrication resulted in the main landing gear not locking down. Several items such as bolts, pins, and bushings were cleaned, lubricated, and adjusted after which the landing gear function normally. The airplane has flown several times without further incident. According to an airframe maintenance logbook entry dated November 12, 2010, the airplane received an annual inspection at a tachometer time of 205.1 hours and a total time 11,080.8 hours. The entry states, "Jacked aircraft serviced landing gear system... ." Items that were replaced included all of the downlock hydraulic hoses and a right hand landing gear actuator fitting. The logbook entry is included in the docket of this report.