On April 7, 1997, at 1308 central daylight time, a Beech BE-95, N2702Y, owned and operated by Stellax Inc., under Title 14 CFR Part 91, was substantially damaged when the right main landing gear did not extend and the left main gear and the nose gear collapsed during the landing roll on runway 12L at the San Antonio International Airport, San Antonio, Texas. The commercial pilot and 3 passengers were not injured. Visual meteorological conditions prevailed for the personal cross country flight and a flight plan was not filed. The flight originated at 1043 from Fort Worth, Texas. During interviews, conducted by the investigator-in-charge, the pilot reported that during the final approach for runway 12L, the right main landing gear failed to extend. The pilot initiated a go-around and performed the emergency procedure for gear extension; however, the right main gear still did not extend. During the subsequent emergency landing, the left main gear and the nose gear collapsed. The airplane departed the runway and came to rest in the grass to the side of the runway. Airport personnel reported damage to the wings and propellers. Maintenance personnel from a fixed base operator reported damage to the fuselage, wing structures, propellers, and wheel wells. Examination of the landing gear system revealed that the uplock assembly mechanism was jammed. In January 1998, the right main gear was examined by an NTSB investigator in Long Beach, California. The investigator found that the bolt which secures the release lanyard to the uplock mechanism had been installed in reverse. The nut on the bolt was on the aft side of the uplock attach point which caused interference between the nut and a metal guide shelf on the airframe. The interference was sufficient to jam the uplock in the locked position. Maintenance records, reviewed by the investigator-in-charge, revealed the right main landing gear uplock cable assembly, P/N 35-815109, was installed, connected, lubed, and safety wired, in February 1997 (tachometer time 531.0 hours, total airframe time 5,431.3 hours). The aircraft was then jacked and the gear swung to verify correct operation of [the] uplock cable and aircraft step and "all [was] found to be operating normally."