On May 6, 2004, about 1130 Alaska daylight time, a tundra tire-equipped Piper PA-18 airplane, N2521S, sustained substantial damage when the right main landing gear collapsed and the right wing struck the ground while landing, about 35 miles west of Kasilof, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight under Title 14, CFR Part 91, when the accident occurred. The solo private certificated pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated about 1000, from the Merrill Field Airport, Anchorage, Alaska. During a telephone conversation with the NTSB investigator-in-charge on May 7, the pilot reported he was landing on a remote sand-covered beach site, commonly known as Polly Creek. He said he flew over the beach, and observed a small creek at the approach end of his intended landing site. The pilot reported that during the landing flare, he encountered a slight downdraft, and he inadvertently allowed the airplane to descend below the intended glide path. He said that the main wheels struck the bank of the creek, and the right main landing gear collapsed. Following the landing gear collapse, the right wing struck the beach. The airplane sustained structural damage to the right wing, both right lift struts, and fuselage. The pilot said that there were no preaccident mechanical anomalies noted with the airplane.