On April 24, 2009, about 1425 Pacific daylight time, a Cessna T210M, N6584B, impacted the terrain during a forced landing on rough terrain about five miles southeast of Hanford, California. The commercial pilot and his three passengers were not injured, but the airplane, which was owned and operated by the pilot, sustained substantial damage. The 14 Code of Federal Regulations Part 91 personal pleasure flight, which departed North Las Vegas Airport about two and one-half hours prior to the accident, was being operated in visual meteorological conditions. The flight was en route to Vacaville, California. No flight plan had been filed. According to the pilot, while en route to Vacaville, he noticed that the fuel quantity was getting lower than he was comfortable with, so he elected to divert into Hanford Municipal Airport to take on some additional fuel. During his descent into Hanford, the engine lost power, and he was unable to get it restarted. He therefore executed an engine-out forced landing in an open field. During the landing roll the airplane's wing came in contact with the rough terrain. A post-accident inspection of the airplane by a Federal Aviation Administration (FAA) Inspector found that there was eight gallons of fuel in the left wing tank, but the right wing tank was empty. Further discussions with the pilot determined that he had the right tank selected when the engine quit, and although he attempted a restart sequence, he did not select the left tank at any time during the restart attempt. According to the pilot, prior to the time he purchased the airplane (about seven years before the accident) it underwent a RAM Aircraft Supplemental Type Certificate (STC) engine conversion, increasing its output to 310 horsepower, and changing its performance and fuel flow figures. The pilot further stated that until about two weeks before the accident, when his current maintenance provider gave him a copy of the RAM conversion performance charts, he did not realize there was a fuel flow difference between the original/standard engine and the RAM conversion. Although he had the RAM charts, the pilot continued to use the performance/fuel flow charts that came with the aircraft at the time of the aircraft's manufacture, and in so doing, on the accident flight he ended up with less fuel remaining than he expected for the time that he had been airborne.