On June 17, 2002, about 2100 eastern daylight time, a Piper PA-28-160, N5369W, was substantially damaged during a forced landing while approaching Hinde Airport (88D), Huron, Ohio. The certificated flight instructor and the non-certificated student pilot were not injured. Visual meteorological conditions prevailed at the time of the accident. No flight plan had been filed for the local instructional flight, conducted under 14 CFR Part 91. According to the flight instructor, he and the student pilot flew to Norwalk-Huron County Airport (5A1), Norwalk, Ohio, for landing practice, then returned to Hinde Airport. When the airplane was on final approach, about 1 mile to runway 11, "a glide was started." The flight instructor asked the student pilot to turn on the landing lights and navigation beacon, to make the airplane more visible to other aircraft in the area. A few seconds later, the flight instructor asked the student pilot to add power. The student pilot answered that he was, but that the engine was not responding. The flight instructor took control of the airplane and switched fuel tanks, but the engine still did not respond. The flight instructor then performed a forced landing to a field off to his right. The field was part of a tree farm, and during the process, the airplane hit 35-40, 1 1/2-inch saplings before coming to a stop. After the airplane came to a stop, the flight instructor performed the shutdown procedures. When he attempted to turn off the magneto switch, he found it was already in the "OFF" position. According to a Federal Aviation Administration (FAA) inspector, when questioned the following day, the student pilot could not remember if he had switched the magnetos to OFF. Another inspector subsequently examined the airplane, and found the left fuel tank to be 5/8 full, and the right tank 1/2 full. A fuel sample was taken, and found to be blue in color. Other inspectors replaced the airplane's damaged propeller, and started the engine during the first attempt. The engine then operated "normally" in the "right", "left" and "both" ignition switch positions.