On October 15, 2005, at 1545 central daylight time, a Bellanca 7GCBC, N2698Z, collided with the water of Lake of the Woods near Williams, Minnesota, following a loss of control. The pilot and passenger were seriously injured. The airplane was substantially damaged. The 14 Code of Federal Regulations Part 91 personal flight was operating in visual meteorological conditions without a flight plan. The flight originated from the Roseau Municipal Airport (ROX), Billberg, Minnesota, at 1400. The pilot reported that after taking off they flew over the passenger's hunting property at altitudes ranging from 500 feet above ground level (agl) to 2,500 feet agl. He reported they continued on to a friend's private airstrip, but no one was there so they decided to fly over the friend's cabin. The pilot reported he flew over the cabin and entered a "standard rate" right turn. He reported they circled 180 degrees and when he tried to level the wings he noticed there was no control pressure on the stick. The pilot reported the right wing dropped and he had limited control of the airplane so he reduced the engine power and added flaps prior to the airplane contacting the water. One witness reported seeing the airplane in a turn prior to it rolling to the right and onto its back. This witness stated the airplane "dove straight in from approx 150 feet." A second witness reported seeing the airplane in a turn with 45 to 60 degrees of bank when it rolled over and descended in a vertical attitude. This witness reported the engine was running and he heard a "pop" sound just prior to the airplane contacting the water. The pilot stated during an interview that the flight controls and engine were operating normally during the flight. He also reported that he did not perform any weight and balance calculations prior to the flight. The pilot stated he weighted 200 pounds, the passenger weighed approximately 280 pounds and that each fuel tank was approximately three-quarters full (27 gallons). The most current weight and balance information located indicated the gross weight of the airplane was 1,650.0 pounds and the empty weight was 1,250.5 pounds. The useful load was listed as being 399.5 pounds. Two pieces of wing spar were forwarded to the National Transportation Safety Board for examination. Both pieces were from the right wing. One piece was from the forward spar and the other was from the aft spar. The pieces were examined at both the American Champion Aircraft Company and the United States Department of Agriculture Forest Products Laboratory. Neither of these examinations revealed any pre-existing fractures of the spar pieces.