On November 5, 2017, about 1140 central standard time, a T-Bird II airplane, N618ER, impacted terrain near St. Marys, Kansas. The pilot and passenger received serious injuries and the airplane was substantially damaged during the accident. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the time. The pilot reported that he and the owner of the airplane planned to take the airplane for a flight around the traffic pattern to see if they were clothed warmly enough for another flight. They departed from runway 36, climbed to about 1,000 ft, and turned left for the downwind when they heard a loud "crack" and the engine started to vibrate. To avoid powerlines, the pilot applied power, but the engine did not respond. He turned sharply left, adding that he tried to stop the turn and decent; however, the elevators and ailerons did not respond. The airplane continued to turn and dropped rapidly, until it impacted a ravine. A neighbor reported that she saw something "flutter" into a tree and something fell when the engine sound "stopped". The object in the tree was retrieved and was the passenger's knitted hat. The top of the hat was "chewed up" and had an area in the shape of a line, burnt/melted in it. The object that fell in the yard was also retrieved and was one of airplane's propeller blades. An examination of the airplane found substantial damage to the fuselage, and one blade from the three-bladed pusher propeller had separated from the propeller hub.