At 0838 Mountain time, the airplane was substantially damaged during landing when its left main landing gear collapsed. Instrument conditions prevailed. The non-scheduled Part 135 domestic cargo flights airline transport pilot was not injured. The pilot later reported the left main landing gear indicator failed to illuminate when he put down the gear. After a go-around, he raised the gear and lowered it again, with the same result. After a tower fly-by, the pilot elected to land with the unsafe gear indication. On landing, the left main landing gear collapsed and the airplane departed the side of the runway, striking a taxiway sign. Examination of the airplane revealed a left main landing gear actuator rod was fractured.
