On January 23, 2007, about 1255 Pacific standard time, a Cessna 172D, N2599U, sustained substantial damage during a forced landing in rough terrain following a loss of engine power in cruise flight near Beaver Marsh, Oregon. The commercial pilot and his passenger were not injured. The airplane was registered to a private individual and operated by the pilot. Visual meteorological conditions prevailed for the personal local flight conducted under 14 CFR Part 91 and no flight plan was filed. The flight departed from Medford, Oregon, at 1214. According to information provided by the Federal Aviation Administration (FAA), the flight was receiving flight following services from air traffic control, and when the engine lost power, the pilot asked for and received radar vectors to the nearest airport, which was Beaver Marsh State Airport. The pilot was unable to reach the airport and performed a forced landing to a recently logged field approximately 1 mile south of the airport. According to the pilot, about 30 to 35 minutes into the flight, while in level cruise flight at 9,500 feet mean sea level (msl), he "noticed (and heard) a power loss of about 300-400 RPM." The pilot attempted to resolve the problem by adding and removing carburetor heat, adjusting the fuel mixture, switching tanks and selecting each magneto separately. However, the power "slowly degraded," dropping to 1,000 RPM by the end of the flight. The pilot described the terrain as "level and forested with coniferous trees." He landed in a clearing in the trees, and during the landing roll, the nose wheel separated, and the airplane nosed down. According to an FAA inspector, the airframe and engine were examined by recovery personnel several days after the accident when they arrived at the accident site to retrieve the airplane. The recovery personnel reported to the FAA inspector that the lower cowling, air box, and carburetor sustained impact damage. Continuity of the carburetor heat, throttle and mixture controls was verified. The spark plug electrodes were noted to be gray to brown in color. When the engine was rotated by hand, thumb compression was obtained on all 6 cylinders, and both magnetos sparked at all terminals. About 12 gallons of fuel were drained from each tank, and there was no evidence of fuel contamination noted.