On February 2, 2001, at 1608 central standard time, a Cessna 310R, N4249C, piloted by a certified flight instructor (CFI), sustained substantial damage when the landing gear collapsed while landing on runway 12R (6,997 feet by 100 feet, dry/asphalt) at the St. Louis Downtown Airport (CPS), Cahokia, Illinois. Visual meteorological conditions prevailed at the time of the accident. The instructional flight was operating under the provisions of 14 CFR Part 91 and was not on a flight plan. The pilot and the dual student were not injured. The local flight departed CPS at 1530 and was returning to CPS at the time of the accident. According to the CFI's written statement, after completing training maneuvers in the practice area the CFI decided to return to CPS and conduct touch-and-go landings. The CFI reported that when they extended the landing gear the three green landing gear position lights illuminated. The CFI stated that they attempted a normal landing and, "Upon touch down the aircraft continued to sink on the left side indicating a problem." The CFI reported that the dual student aborted the landing and they departed the traffic pattern in order to assess the problem. The CFI stated that he cycled the landing gear and the three green landing gear position lights illuminated when the landing gear were extended. The CFI reported that he performed a fly-by past the control tower and the air traffic control (ATC) personnel indicated that all three landing gear were extended. The CFI stated that he attempted another landing and the airplane continued to drop on the left side subsequent to the touchdown. The CFI reported that he aborted the landing and made the decision to attempt a gear-up landing on the next landing attempt. The CFI stated that on the next landing approach the decision was made to go-around and during the go-around the ATC personnel informed him that his left landing gear was "[hanging] by itself". The CFI reported that he then decided to attempt a landing with the landing gear extended. The CFI stated that, "Upon touch down the left gear collapsed as it did the other two times I tried to keep [the airplane] on the right gear as long as possible. As we slowed the left wing and prop touched the ground and pulled us off the left side of [runway] 12R hitting a runway light." A representative of the Federal Aviation Administration performed a post-accident inspection of the airplane and its landing gear system. No anomalies were found with the landing gear system that could be associated with a pre-impact condition. All fractured portions of the landing gear system had signatures consistent with overload failure. The accident airplane was involved with two previous occurrences in which the left landing gear had collapsed. The first was on June 27, 1998, and the cause of the gear collapse was undetermined. The second occurrence was on May 15, 2000, and was attributed to the failure of a through-bolt in the gear retraction linkage. The accident flight was the second flight since the maintenance release for the damages that were incurred during the May 15, 2000, accident. The first flight was a maintenance test flight and no anomalies were noted during the flight.