On August 4, 2011, at 0830 Pacific daylight time, a Cessna 140, N2199N, collided with trees during a forced landing near Wilkeson, Washington. The airplane sustained substantial damage. The private pilot and one passenger were not injured. The pilot, who was also the registered owner of the airplane, was operating it under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the local area flight. The pilot reported in a written statement that he had washed the airplane the day before the accident. Prior to the accident flight, he did an extensive preflight and verified no water was in the fuel. He also verified that the scat tubing was free of moisture. The run up was uneventful and during takeoff, he brought the throttle to takeoff power and released the brakes. The pilot stated that about halfway down the runway, the engine began to lose power and sputter. He verified the fuel selector and carburetor heat positions and then began pumping the throttle. He was unable to sustain engine power and force-landed the airplane into trees. The pilot reported during a phone conversation following the accident, that when he had washed the airplane on prior occasions, the airplane had experienced momentary power interruptions which he had attributed to residual water. During the post accident inspection, a Federal Aviation Administration accident coordinator test ran the engine using the airframe fuel system, fuel, and controls. The engine was test run from idle to 2,200 revolutions per minute with no operational anomalies.