On March 18, 2018, about 0830 Pacific daylight time, a Cubcrafters CC11-160 airplane, N1951B, crashed in a river following a wire strike near Browns Valley, California. The private pilot sustained serious injuries. The airplane sustained substantial damage to the fuselage and both wings. The airplane was registered to Plane Fun LLC., Roseville, California, and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a local personal flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated from the Lincoln Regional Airport (LHM), Lincoln, California at 0800. The pilot reported that he was maneuvering about 500 ft over the unpopulated area and studying the river when the airplane must have lost altitude and hit something. A fire broke out and the airplane subsequently crashed in the river. The pilot reported that he was later told that he hit a power line. A witness located on the rivers shore, near the accident site, reported that he observed a yellow airplane maneuvering at a height a little higher than a telephone pole. The airplane circled his location a few times before he lost sight of it behind a pile of dredger tailings. He then heard what he described as an explosion. When he reacquired the airplane, he noticed that there were flames coming out of the right side of the fuselage. He again lost sight of the airplane just before it impacted the river. The river runs generally east to west. The height of the powerlines was about 200 ft and run across the river generally north and south and extend approximately 1 mile. The wreckage was located approximately 2,000 ft east of the powerlines, in about 3 ft of water. The powerline company sent a representative to assess the damage to the power lines. The representative reported that six power lines were separated, and 16 residences were without power. The pilot reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation.