On March 23, 2009, about 1800 Pacific daylight time, a Piper PA-28-181, N1857H, experienced a loss of engine power followed by a forced-landing in a field short of Firebaugh Airport, Firebaugh, California. The pilot was operating the airplane under the provisions of 14 Code of Federal Regulations Part 91. The certificated private pilot was not injured. The airplane sustained substantial damage to the left wing spar. The personal flight departed Palm Springs International Airport, Palm Springs, California, at 1400, with a planned destination of Reid-Hillview Airport, San Jose, California. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot reported departing Palm Springs with about 45 gallons of fuel onboard. She initiated a northbound climb to an altitude of 10,500 feet and then changed course to the northwest. About 3 1/2 hours into the flight, she checked the fuel gauges, and observed slightly less than 5 gallons remaining in the right tank and less than 10 gallons in the left tank. The fuel selector was set to the right tank, and she presumed that there was enough fuel remaining for about 1 hour 10 minutes of flight. About 15 minutes later, the engine stopped producing power. She checked the fuel gauges, and observed the right needle was indicating zero fuel. She switched to the left tank, and the engine regained power. The pilot then diverted to the northeast with the intention of landing at Firebaugh Airport. According to a statement made to the Fresno County Sheriff, she was initially unable to locate the airport, and circled around the city of Firebaugh. She then located the airport, and during the landing attempt the engine lost power again. The pilot force-landed in a plowed field. An FAA Inspector responded to the accident site. He examined the airplane, and reported that both fuel tanks were intact and absent of fuel. The inspector did not observe fuel leaks on the external surfaces of the airplane. Recovery personnel drained approximately 32 ounces of fuel from the airplane, and observed no indications of fuel leakage. Additionally, all fuel lines within the engine compartment were intact. The pilot stated that she was certain she leaned the fuel mixture during the flight. However, she further reported that she often had difficulty accurately adjusting the fuel mixture on the accident airplane type, due to its mixture lever. She stated that she was more familiar, and comfortable, adjusting the mixture on an airplane equipped with a Vernier mixture control. The accident location was approximately 71 miles south of Reid-Hillview Airport. The pilot reported encountering 35 knot headwinds during the flight. In a written statement the pilot reported that the accident could have been prevented with, "better planning/execution."