On October 14, 2015, about 1145 Pacific daylight time, an experimental amateur built Christopher Kitfox 5 airplane, N533RC, collided with a fence following a loss of engine power during the takeoff climb from a private grass strip near Battle Ground, Washington. The private pilot and passenger were not injured; the airplane sustained substantial damage. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The local flight was originating at the time of the accident. According to the pilot, after take off from his grass airstrip, he made a left 45o climbing turn when the engine began to run rough, then it regained full power. The airplane climbed to about 300 ft above ground when the engine ran rough again, then lost power. The pilot realized that he did not have sufficient altitude to make it to nearby Goheen Airport (W52), Battle Ground so he turned back toward the departure airstrip as he knew there were multiple open fields in the area. As he maneuvered around trees and fences for a forced landing, the airplane subsequently collided with a fence and nosed over, coming to rest inverted. The pilot stated that he had drained fuel during the preflight check and reported no water present; however, he believed that there may have been a "slug of water" in the fuel line. A Federal Aviation Administration (FAA) inspector examined the engine. The pilot had fueled the airplane from a nearby gas station. The fuel is placed in a plastic cylindrical gas container and then the airplane is refueled. A visual inspection of the fuel revealed no contamination. The sample of fuel recovered from the filter housing was opaque and cloudy compared to the sample taken from the airplane's header tank. The FAA inspector reported that after cleaning the oil-soaked spark plugs, and installing a fuel filter, he checked the fuel pressure of both pumps at 48 psi, which fell in the normal operating range of the fuel pump. The engine was then started and ran normally, except for a vibration, which was attributed to the broken propeller blades.