On October 28, 2007, approximately 1730 mountain daylight time, N8251M, a Cessna T210K, sustained substantial damage during landing with the nose gear retracted at Los Alamos Airport, Los Alamos, New Mexico. Visual meteorological conditions prevailed at the time of the accident. The business flight was being conducted on an instrument flight rules flight plan under the provisions of Title 14 Code of Federal Regulations Part 91. The private pilot and passenger were not injured. The flight originated at Carlsbad, New Mexico, at 1430, and was destined for Los Alamos. According to the pilot's statement, during his approach to Los Alamos, he attempted to extend the landing gear. During the gear extension, the pilot noted that "something did not sound right, and [I] did not get a gear down indication in the cockpit." The pilot cycled the landing gear approximately "10 to 15 times in various speeds, power settings, g-loads, and attitudes" with no result. The pilot attempted to extend the landing gear manually, again with no result. The pilot then decided to fly the airplane to the airport in Santa Fe, New Mexico, which has a control tower, and have the tower controllers visually verify that the landing gear was down. The tower controller at Santa Fe advised the pilot that the airplane's nose landing gear was not extended and the nose gear doors were closed. After several more unsuccessful attempts to troubleshoot the problem, the pilot returned to Los Alamos and landed the airplane with the nose gear retracted. A Federal Aviation Administration (FAA) inspector and a mechanic examined the aircraft and, during the examination, operated the landing gear. The inspector stated that the nose landing gear doors were closed, the nose landing gear was retracted, and the main landing gear was extended at the start of the examination. Maintenance personnel placed the airplane on support jacks and applied hydraulic power to the landing gear system. The landing gear handle was selected to the up position and all three landing gear came up and locked. When the landing gear handle was selected to the down position, the main landing gear came down and locked. The nose landing gear unlocked, the nose landing gear doors did not open and the nose landing gear rested on the doors. The mechanic pushed lightly on the gear doors, they opened and the nose landing gear came down and locked. The inspector noted that there was a wear mark on the area where the nose landing gear door guide tabs came together, but there was no other evidence of wear or binding. Several operations of the landing gear followed, and the landing gear operated normally without binding. Examination of the aircraft revealed the lower nose keel angles and doublers were abraded. The FAA inspector also reported that the airplane was equipped with a modification that removes the hydraulic actuators from the nose landing gear doors and replaces them with a mechanism that closes the doors when the nose landing gear strut pushes against a roller as it reaches the up-and-locked position. A review of the maintenance records revealed an annual inspection was performed on October 3, 2007. As part of the inspection, the nose gear door roller was repaired. The reason for the failure of the nose landing gear could not be determined.