On July 14, 1998, at 1400 eastern daylight time, a Cessna 190, N56W, operated by a commercial pilot experienced a left main gear collapse during a landing roll on runway 27R, at the Oakland County Airport, Pontiac, Michigan. The pilot was not injured and the airplane was substantially damaged. The 14 CFR Part 91 personal flight was operating in visual meteorological conditions without a flight plan. The flight originated from the Detroit Metro Airport, Detroit, Michigan, at 1330 eastern daylight time. The pilot reported he made a "normal gentle 3 point landing" and during the landing roll the left main gear collapsed. He reported the airplane was traveling approximately 15 mph when the gear collapse took place. He reported, "Aircraft had gear replaced and blasted and painted three years or so earlier. ... Aircraft had not been flown in over three years since gear work was done." The airplane was inspected by an Inspector from the Federal Aviation Administration Belleville, Michigan, Flight Standards District Office. He reported the landing gear spring had separated at the support wedge. Inspection of the failed spring surface revealed an area of rust. The spring also contained "deep pitting on the upper surface in the area of the fracture." This assembly appeared to have been recently painted.