On March 20, 2014 about 2045 mountain daylight time, a Bellanca 17-31ATC, N28119, sustained substantial damage after the landing gear collapsed at the Salt Lake City International Airport (SLC), Salt Lake City, Utah. The pilot, the sole occupant, was not injured; the airplane sustained substantial damage to the right wing aileron. The airplane was registered to, and operated by, the pilot under the provision of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, and no flight plan was filed. The flight originated from the Roosevelt Municipal Airport (74V), Roosevelt, Utah at about 1950. The pilot reported that during the approach he conducted his usual pre-landing checklist, which included verifying the landing gear position and indicator lights four separate times. He conducted a normal, uneventful landing. During the landing roll the landing gear warning indication light activated and the right main landing gear green indicator light extinguished. The right wing dropped to the runway and the airplane slid before coming to a rest just off of the runway surface. Postaccident examination of the landing gear by a mechanic and the pilot revealed that the right main landing gear extension spring appeared to be compressed; when tested, it produced 19-20 pounds of pressure. The extension springs from the nose and left landing gear assemblies were also removed and tested; they both produced about 40 pounds of pressure. The pilot reported that he subsequently purchased and tested three new springs, all of which produced about 44 pounds of pressure. The new springs were installed on the airplane and no further landing gear anomalies were noted.