On June 21, 1997, at 1200 central daylight time (cdt) a Champion 7ECA, N7506F, piloted by a private pilot receiving dual instruction from a certificated flight instructor, was substantially damaged during a hard landing. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 instructional flight was not operating on a flight plan. The private pilot reported no injuries, the flight instructor reported minor injuries. The flight departed a restricted landing area near Willard, Missouri, at 1145 cdt. The flight instructor said, "...our airspeed was about 70 to 75 MPH. As we passed over the tree the pilot reduced [the] power and flared to high (about 20 feet above the ground). This caused a high sink rate and a hard landing." During an interview with the flight instructor he said he knew the airplane was sinking pretty good after it passed over the trees. He said he told the pilot to increase the power. Upon seeing the pilot did not add power, the instructor said he tried to rapidly apply power but was unable to do so because the pilot was trying to reduce it. The instructor said the airplane had made a go-around before the landing approach that lead to the hard landing. The pilot receiving the dual instruction said the first landing approach resulted in a go-around because the airplane's sink rate was too high. During the second approach the pilot said he reduced the power as the airplane flew over the trees. He said the airplane just went down after he reduced the power. He said the airspeed indicator showed about 60 miles per hour during the landing approach. A witness to the accident said the airplane was "...slow and too low. The pilot flared 20 feet high without power and stalled the airplane." During an interview, the witness said he heard the power increase just before the airplane made the hard landing. The instructor said he and the pilot receiving the instruction had been flying a Piper PA-12. He said the PA-12 floats on landing. He said he had never flown the Champion 7ECA from the rear seat before the accident flight. He said he had acquired about 12 hours of flight time in airplanes similar to the accident airplane. He was asked when the last flight in this type airplane had been made. He said he couldn't recall.