On January 10, 2005, at 1045 eastern standard time, a Piper PA-30, N7547Y, was substantially damaged while landing at the Millville Airport (MIV), Millville, New Jersey. The certified flight instructor and certificated private pilot were not injured. Instrument meteorological conditions prevailed and an instrument flight rules (IFR) flight plan was filed for the flight, which originated at the Cape May County (WWD), Wildwood, New Jersey. The instructional flight was conducted under 14 CFR Part 91. According to the private pilot, he was flying the ILS runway 10 approach at Millville; however, during the approach, he was high on the glide slope and left of course. He "broke out of the clouds" at 600-700 feet, and approximately 1,000 feet down the length of the runway. At that time, the flight instructor said, "let's get out of here," and the private pilot retracted the landing gear and added power for the missed approach. The flight instructor then took the controls and said "he had the airplane," initiating a tight, right hand pattern for runway 28. As the airplane touched down, or just prior, the gear warning horn went off and the flight instructor noted that the landing gear was still retracted. The airplane then landed on its belly, struck both propellers, and skid several hundred feet before coming to rest at the intersection of runway 14-32. The private pilot then secured the airplane, and both pilots egressed. In a written statement, the flight instructor stated that during the ILS runway 10 approach, at the outer marker, the final landing check was completed and the gear was lowered. He additionally stated that the private pilot confirmed the gear was down through the illumination of the "green down light," and visual confirmation of the gear down in the mirror located on the left engine cowling. The approach was completed and during the circle to land, the private pilot "must have raised the gear and not remembered." The flight instructor then completed the circling approach, and "landed gear up." The flight instructor did not recall hearing the gear warning horn. According to a Federal Aviation Administration (FAA) inspector, the airplane was jacked up after the accident, the landing gear was lowered, and the airplane was towed to the ramp. The landing gear was then cycled up and down several times, and no mechanical anomalies were noted.