The pilot stated that the tailwheel-equipped airplane started veering to the right during the landing roll. Despite his control inputs, the airplane continued to veer to the right and tipped onto its left wingtip before coming to rest upright in a snow bank. According to the pilot, the left tailwheel steering link spring retaining clip was missing, and a search failed to locate it on the runway or near the airplane. A missing steering link would allow the tailwheel to freely caster.
