HISTORY OF FLIGHTOn January 14, 2017, about 1715 eastern standard time, an amphibious experimental amateur-built Buccaneer II B, N696FT, was substantially damaged after it impacted high voltage power lines and a river near Mayo, Florida. The sport pilot was fatally injured. The airplane was registered to and operated by the pilot 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 personal flight. According to a friend, the pilot had flown to the Suwannee River in Blue Springs Park to meet him and camp next to the river for the night. The pilot landed to the north on the river, flying over power lines during the landing approach. About 20 minutes after the pilot landed, his friend arrived. The two spoke briefly; the friend told the pilot that he needed to retrieve a life vest that had floated downstream; the pilot offered to help after he finished unloading his airplane. The friend paddled downstream and subsequently heard the airplane takeoff. Multiple witnesses in the area of the accident site reported seeing the airplane take off northbound along the Suwannee River, complete a 180° left turn, descend below treetop level, and fly southbound over the river out of view. Shortly thereafter, witnesses reported hearing a loud "boom" followed by the engine "going quiet" and a power outage. One witness, who was located about 1 mile from the power lines, stated that he saw the airplane flying about 30-40 ft above the river when it "suddenly flipped backwards and then hit the water." PERSONNEL INFORMATIONThe pilot held a sport pilot certificate, an airframe mechanic certificate, and a light sport repairman certificate for three airplanes, none of which were the accident airplane. His pilot logbook was not located. His most recent Federal Aviation Administration (FAA) third-class medical certificate was issued on May 17, 2016. He reported 8,000 total hours of flight experience on that date. During his previous medical exam, on March 6, 2014, he reported 982 hours of flight experience. AIRCRAFT INFORMATIONThe airplane was primarily constructed from aluminum and Dacron, with a fiberglass hull. It was powered by an 80-horsepower Rotax 912 four-cylinder engine mounted on a pylon in a pusher configuration. The pilot purchased the airplane about 9 months before the accident. FAA records showed that a registration application had been submitted and later extended, but that no current registration information was on file. The most recent entry found in the engine maintenance records was dated June 14, 2015. The airframe records were not located. METEOROLOGICAL INFORMATIONThe closest weather reporting facility, Cross City Airport (CTY), Cross City, Florida, was located about 30 nautical miles south of the accident site. The 1710 surface weather observation included broken clouds at 4,400 ft, wind from 030° at 5 knots, visibility 10 statute miles, temperature 22°C, dew point 17°C, and altimeter setting of 30.24 inches of mercury. A witness reported that, around the time of the accident, grey clouds were in the area as the sun set. He stated that the light and sky conditions made the power lines difficult to see. AIRPORT INFORMATIONThe airplane was primarily constructed from aluminum and Dacron, with a fiberglass hull. It was powered by an 80-horsepower Rotax 912 four-cylinder engine mounted on a pylon in a pusher configuration. The pilot purchased the airplane about 9 months before the accident. FAA records showed that a registration application had been submitted and later extended, but that no current registration information was on file. The most recent entry found in the engine maintenance records was dated June 14, 2015. The airframe records were not located. WRECKAGE AND IMPACT INFORMATIONThe wreckage came to rest inverted and partially submerged in shallow, fast-moving water beneath power lines that ran roughly east-west and crossed the Suwanee River below treetop level. All major components were accounted for at the site; the airplane was intact with the exception of the left float, which was located downstream. When recovered, the airplane was set upright on the shore for examination. There was leading edge damage to both wings near the wing roots. The structural tubing along the right wing leading edge was fractured. The wing struts were separated about midway between the lower and upper attachment points. The windscreen and its supports were fractured. The hull was fractured in multiple places. The propeller was separated from the propeller flange, and the flange remained attached to the crankshaft. All three of the composite blades remained attached to the hub; two blades were fractured about midpoint on the blade. The powerlines directly overhead of the accident site displayed striations consistent with impact. MEDICAL AND PATHOLOGICAL INFORMATIONThe Office of the Medical Examiner, Tallahassee, Florida, performed an autopsy of the pilot. The cause of death was listed as multiple blunt force injuries. The autopsy identified an enlarged heart with left ventricular hypertrophy and cardiac muscle fibrosis. The FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicological testing on specimens of the pilot. Gabapentin was detected in the liver and blood. Gabapentin is an antiseizure medication that is also used to treat chronic pain and is marketed under various names, including Neurontin. It carries the warning, "Prescribers and patients should be aware that patients' ability to assess their own driving competence, as well as their ability to assess the degree of somnolence caused by gabapentin, can be imperfect." The level of gabapentin in the blood was well below a level that is considered therapeutic. Testing also detected the non-impairing pain reliever, ibuprofen, in urine.