On February 1, 2007, about 1615 mountain standard time, a Cessna 414A, N6631C, piloted by a private pilot, received substantial damage when the right main landing gear retracted upon landing on runway 25 (4,700 feet by 75 feet, grooved asphalt) at Dickinson - Theodore Roosevelt Regional Airport (DIK), Dickinson, North Dakota. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 business flight was operating on an instrument rules flight plan. The pilot was uninjured. The flight originated from Billings Logan International Airport, Billings, Montana, about 1445, en route to DIK. The pilot reported that as he neared DIK, he attempted to lower the landing gear. The pilot reported that he received a down and locked indication from the nose gear; however, both main landing gear did not show a down and locked indication. After several attempts at recycling the landing gear, the pilot tried to use the emergency gear extension method but still did not receive a down and locked indication for the main gear. The pilot then contacted an individual at the airport who informed the pilot that his main gear appeared to be down. The pilot then landed the airplane, during which the right main gear retracted. According the Federal Aviation Administration inspector, an Airframe & Powerplant (A&P) mechanic with Inspection Authorization (IA) reported that the airplane was placed on jacks in order to cycle the landing gear system. The landing gear system operated normally, no anomalies were detected, and no repairs were made to the landing gear system.