On June 28, 1997, at 0820 central daylight time, a Cessna 402B, N901BC, registered to Springfield Aircraft Charter & Sales, Inc., of Springfield, Missouri, sustained substantial damage during a landing on runway 20 (7,003' x 150' dry/concrete) near Springfield, Missouri. The airline transport rated check pilot said the airplane swerved and the left main landing gear collapsed. Both pilots reported no injured. The 14 CFR Part 91 crew training flight was operating in visual meteorological conditions. No flight plan was on file. The local flight departed at 0720. The airline transport rated pilot said he was giving instruction to the commercial rated (single engine) pilot who was occupying the left seat. He said that the airplane swerved on landing and the damage occurred before he could take remedial action. An inspection of the airplane subsequent to the accident failed to reveal any preexisting mechanical anomalies. The Federal Aviation Administration inspector said that the damage to the airplane was bent structure in the wheel well area and the left main landing gear collapsed from what he described as "side load."