The pilot of the certificated experimental exhibition category bi-plane was landing on a private turf runway. During the landing rollout, the airplane's left main landing gear axle fractured and the left landing gear wheel assembly departed the airframe. The airplane veered to the left and the remaining portion of the left landing gear collapsed. The propeller, and the lower left and right wings contacted the runway, and were substantially damaged. Postaccident inspection of the airplane revealed a crack that had propagated through a manufacturer welded area near the wheel assembly. The airplane was manufactured in 1961. It had been operated for about 760 total hours since new, and 7 hours since its most recent condition inspection, which was performed about 11 months prior. A search of the Federal Aviation Administration service difficult reports database for the accident airplane make and model did not reveal any previous similar landing gear failures.