On April 18, 1999, about 1130 hours Pacific daylight time, a Beech A23-24, N7965L, registered to a private individual and operated by the pilot, experienced a partial loss of engine power during initial climb from the uncontrolled Yerington Municipal Airport, Yerington, Nevada. The pilot made a forced landing beyond the runway's departure end and collided with a berm. Visual meteorological conditions prevailed, and no flight plan was filed. The airplane was substantially damaged. Neither the private pilot nor the two passengers were injured. The personal flight was performed under 14 CFR Part 91, and originated from Yerington about 1129. The pilot reported to the Safety Board investigator that the airplane's engine appeared to properly function during the engine run-up, and he proceeded to takeoff from the beginning of runway 01. After climbing between 100 and 200 feet above the ground, the engine "bogged down." The pilot stated that he tried to regain power by adjusting the throttle and mixture controls, but "nothing happened." The pilot indicated that because engine power was not restored he aborted the flight. Responding Lyon County Sheriff deputies reported observing evidence that the airplane struck the ground about 803 feet north of the runway, then impacted an irrigation ditch before coming to rest 97 feet north of the ditch. The Federal Aviation Administration (FAA) reported that the pilot was issued a private pilot certificate on September 24, 1997. On his certificate application he reported having logged 54.1 total flight hours. By the accident date he had a total of about 69 hours of flight time, of which about 4.9 hours were in the Beech A23-24 airplane. According to the FAA coordinator, results of the postimpact airplane examination revealed no indication of blockage in the fuel system screens or lines, and the fuel tanks were found at least half full of fuel. No anomalies were found with the fuel selector handle. The throttle and mixture controls were intact and functional. The magnetos operated normally. The engine was operated to a low power level, and no malfunctions were noted. Based on the weather report at the Reno, Nevada, airport, a density altitude of 5,800 feet was computed.