On September 14, 2018, about 1718 Pacific daylight time, a Cessna T210 airplane, N5340Y, was substantially damaged during landing roll at San Luis County Regional Airport (SBP), San Luis Obispo, California. The private pilot was not injured. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed for the cross-country flight. The flight originated from John Wayne-Orange County Airport (SNA), Santa Ana, California at 1613, with a destination of SBP.The pilot reported that during the approach to land at SBP, he selected the landing gear to the DOWN position, after which he felt the gear extending into place. Following the gear extension, he observed the left main landing gear out the window and felt that everything was normal. As the airplane contacted the runway at 65 to 70 knots, he felt a "…bump up from the right" as the nose landing gear immediately made contact with the runway. The airplane veered to the right as it exited the runway, and completed a 180° turn before coming to rest in the runway safety area. Additionally, the pilot reported that he did not hear the landing gear warning horn, nor did he remember seeing the landing indicator lights during the approach. The pilot wore a noise cancelling headset during the flight. Initial examination of the airplane by a Federal Aviation Administration inspector revealed that the right main landing gear was retracted, and that the right horizontal stabilizer and the right elevator had impacted the ground and were buckled upwards. Subsequent to the airplane being relocated to a facility on the airport, the landing gear extension motor was replaced. The landing gear was tested, and no anomalies were noted. The warning horn sounded, and landing gear indicator lights illuminated during the testing. It was revealed during the examination that the landing gear extension motor was the original pump installed during the manufacturing of the airplane. When the motor was disassembled, internal wear was observed. The six-seat, high-wing, retractable tricycle-gear airplane, serial number (S/N) 21064173 was manufactured in 1981 and had accumulated 6,813.5 hours total airframe time at the last annual inspection on March 22, 2018.