On October 15, 2006, at 1400 mountain standard time, a Monocoupe 110 Special, N501W, veered off the runway after the left landing gear collapsed during the landing rollout at Chandler Municipal Airport (CHD), Chandler, Arizona. The owner/pilot was operating the airplane under the provisions of 14 CFR Part 91. The airline transport pilot, the sole occupant, was not injured; the airplane sustained substantial damage. The cross-country personal flight departed Eloy, Arizona, about 1330, with a planned destination of Chandler. Visual meteorological conditions prevailed, and no flight plan had been filed. The approximate global positioning system (GPS) coordinates of the primary wreckage were 33 degrees 16.05 minutes north latitude and 111 degrees 48.24 minutes west longitude. The pilot reported that upon touchdown on runway 22L, the left landing gear forward tube failed "just below the mounting lugs" and the airplane skidded off the left side of the runway. The airplane nosed over when it contacted soft sand, and the vertical stabilizer sustained substantial damage. The pilot reported that the last annual inspection occurred on February 3, 2006. At the time of the accident, the recorded airframe total time was 723 hours. The pilot indicated that the airplane was originally built in the 1930's. The landing gear forward attach point was located under a fairing. A Federal Aviation Administration inspector examined the failure point but was unable to determine the exact mode of failure.