On March 12, 2008, at 1140 mountain daylight time, a Spartan 7W, N17662, registered to and operated by the pilot, was substantially damaged when the main landing gear collapsed during a stop and go landing on runway 33 at Santa Fe Municipal Airport (SAF), Santa Fe, New Mexico. Visual meteorological conditions (VMC) prevailed at the time of the accident. The personal flight was being conducted under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91 without a flight plan. The pilot and a pilot-rated passenger were not injured. The local flight originated at SAF approximately 1030. According to the pilot's accident report, he was practicing full stop landings on runway 33. The airplane landed "firmly" on the main landing gear and on centerline. Shortly thereafter, the right main landing gear collapsed and the airplane began veering to the right. The pilot made corrective inputs but could not maintain directional control. The airplane departed the runway. The left main landing gear then collapsed. Both wings were bent and the fuselage sustained bulkhead damage. The airplane was removed from the runway, taken to a hangar, and placed on jacks. Both left and right main trunions were sent to NTSB's Materials Laboratory for examination. According to the metallurgist's factual report, the fracture surfaces of the right main landing gear strut "appeared relatively rough and light gray consistent with overstress fracture of a cast aluminum alloy." Examination of the corner radius where the outboard support flange intersects the vertical tube "showed areas with a smooth faceted appearance with curving boundaries consistent with fatigue." The fracture faces of the left main landing gear strut "showed features indicative of overstress separation...An area of the fracture surface was smooth and shiny, features consistent with smearing associated with the compression side of an overstress fracture in bending."