On September 16, 1993, at 1125 hours eastern standard time, a Piper PA23, N4470P, piloted by a certificated flight instructor (CFI) and multiengine student, sustained substantial damage when it touched down on the runway at Hobart, Indiana with the landing gear up. The two occupants reported no injuries. Visual meteorological conditions prevailed for the local flight, no flight plan was filed. The flight operated under 14 CFR Part 91, and originated from Hobart, Indiana, approximately 1120 hours. The CFI reported he and the multiengine commercial certificated student departed with the intention of practicing pattern work and single engine procedures. The airplane was on a left downwind leg for Runway 18 when the CFI simulated a right engine failure. He instructed the student to proceed with a single engine landing. The CFI stated "...Upon crossing the threshold for the flare we just seemed to drop and the next thing...we were scraping the ground... ." The CFI stated they had placed the landing gear handle in the gear down position, and observed three green lights, indicating the gear was down and locked. Postaccident investigation revealed the landing gear selector was in the gear down position. The landing gear was up, and the gear doors were closed. The airplane was lifted, placed on jacks, and the landing gear was pumped down manually. The FAA Inspector reported the gear extended and locked normally, with corresponding green light indications. There was no indication of preimpact malfunction.