On March 1, 2002, at 1936 mountain standard time, a Cessna 421C, N421DG, registered to and being flown by a private pilot, sustained substantial damage during a gear up landing on runway 31 at the Friedman Memorial airport, Hailey, Idaho. The pilot and passenger were uninjured. Visual meteorological conditions existed and an IFR flight plan had been activated. The flight, which was personal, was operated under 14CFR91, and originated from Santa Monica, California, earlier in the day, and was destined for Hailey. As the aircraft approached Hailey, the pilot reported that he was unable to obtain a down and locked status on the right main landing gear. He then attempted a manual extension of the landing gear using the nitrogen blow down system, but again was unable to get a down and locked indication on the right main gear. The aircraft was landed with the nose and left main gear extended and during the initial landing roll the right wing impacted the runway. An examination and testing of the aircraft's landing gear and associated hydraulic systems was conducted under the oversight of an inspector from the Federal Aviation Administration's (FAA) Flight Standards District Office (FSDO) at Boise, Idaho. The hydraulic system was drained and the fluid was captured. Examination of the fluid yielded no particulate contaminants but a small amount of water was found in the fluid. The hydraulic system was subsequently replenished and the aircraft was placed on jacks. The landing gear was then cycled up and down repeatedly with no malfunction noted. The landing gear was then extended utilizing the emergency extension system, again with no malfunction (refer to ATTACHMENT FAA-I). The surface temperature at Friedman airport was well below freezing several hours before and after the accident.