On September 17, 2012, about 1200 Alaska daylight time, a Piper PA-22-160 airplane, N8433D, sustained substantial damage when it collided with terrain while maneuvering at a low altitude, about 15 miles south of Talkeetna, Alaska. The airplane was being operated by Alaska Floats and Skis, Talkeetna, as a visual flight rules (VFR) instructional flight, under the provisions of Title 14, Code of Federal Regulations, Part 91, when the accident occurred. Visual meteorological conditions prevailed. The certificated flight instructor received serious injuries, and the private pilot received minor injuries. The flight departed Talkeetna about 1150. In a written statement to the NTSB dated October 1, the flight instructor reported that after departing from the Talkeetna Airport, they flew south towards Willow, Alaska. The pilot flew along the Susitna River at 200 AGL to work on coordination, and get the feel of the airplane. After about 10 minutes the flight instructor took control of the airplane, and made a left turn toward a gravel bar on the east side of the river. The flight instructor said that during the turn the nose started to drop, the airplane descended, and it sounded like the speed was increasing. He then added engine power, leveled the wings, and released the back pressure on the control yoke, trying to break any stall, but the airplane continued to descend. As the airplane approached the ground, he added more back pressure on the control yoke with no response. The airplane impacted the ground, sustaining substantial damage to the wings and fuselage. The flight instructor reported that there were no preaccident mechanical anomalies with the airplane.