At about 14:07 EST, a Cessna 210L suffered a no-gear landing at Ohio State University Airport. The pilot and passenger were not injured. The pilot had been practicing instrument procedures and was returning to the airport. He selected the gear down and observed the nose gear extended in a mirror, and landed on runway 27. The main gear, however, were not extended. The pilot said he heard a horn just before touchdown, but thought it was a stall warning horn. The pilot said he was never exposed to the sound of the landing gear warning horn during his previous instruction in the airplane. The accident flight was his first flight in the airplane as pilot-in-command. The president of the flying club had told the pilot the landing gear motor occasionally overheated and asked that the gear not be cycled too often. An inspector observed the landing gear motor circuit breaker tripped. He added that, before the accident, the problem with the landing gear motor was unable to be reproduced during the last annual inspection, and the airplane was returned to service.