On May 17, 1999, at 1840 central daylight time (cdt), a Beech 99A, N133BA, operated by an airline transport pilot, sustained substantial damage when the airplane's left main landing gear collapsed during landing roll at the Bemidji-Beltrami County Airport, Bemidji, Minnesota. Visual meteorological conditions prevailed at the time of the accident. The systems flight test was being conducted under 14 CFR part 91. No flight plan was on file. The pilot reported no injuries. The local flight originated at Bemidji, Minnesota, at 1740 cdt. In his written statement, the pilot said that following takeoff and raising the landing gear, the red warning light in the landing gear handle failed to go out. The pilot said that he recycled the landing gear, but could not get the red light to go out. The pilot said that he continued with the test flight. On his return to the airport the pilot said he put the landing gear handle down and nothing happened. He recycled the handle two additional times with no results. The pilot overflew the airport and confirmed with his company's maintenance that the landing gear were still up. The pilot said that he then manually pumped the landing gear down, but only the nose gear and right main gear green indicator lights illuminated. The pilot overflew the airport again. His company's maintenance told him that the three gear were down. The pilot came into land. He said that he touched down on the right main gear first, and then gently lowered the left main gear to the runway. The landing gear held. The pilot said he then tried to apply some reverse thrust. Suddenly, the left main gear collapsed, and the left wing struck the runway. The airplane slid off of the left side of the runway and came to a stop in the grass. A Federal Aviation Administration (FAA) inspector examined the airplane at Bemidji-Beltrami County Airport. The outboard two feet of the airplane's left wing, to include the rear spar, was bent upward approximately 10 degrees. The bottom wing skin and wing tip showed heavy longitudinal scraping. The bottom outboard 12 inches of the left aileron was scraped longitudinally. The bottom of the left engine nacelle near the exhaust was bent inward and showed longitudinally-running scrapes in the metal. The trailing edge and bottom of the airplane's left flap was bent upward. The left propeller's three blades were bent rearward and showed torsional bending and chordwise scratches. The left main gear doors showed scraping. The left main landing gear actuator shaft was broken aft. Flight control continuity was confirmed. Examination of the airplane's engines, engines controls, and other airplane systems revealed no anomalies. An examination of the left main landing gear actuator revealed no anomalies.