On June 19, 2005, about 0730 mountain daylight time, an experimental category, tail wheel equipped, Adkins Ridge Runner II, N825PB, sustained substantial damage during the takeoff roll at the Pocatello Regional Airport, Pocatello, Idaho. The airplane was being operated as a visual flight rules (VFR) local area flight under the provisions of Title 14 CFR Part 91 when the accident occurred. The solo commercial pilot was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the flight. In a written statement to the National Transportation Safety Board (NTSB), dated June 21, the pilot reported that after applying full power for takeoff the airplane turned to the left. He reported that corrective actions were attempted; however the airplane "spun around" and the left main gear collapsed. During a telephone conversation with the NTSB (IIC) on June 28, the pilot stated he had accumulate approximately 5 hours and fifty landings in tail wheel equipped aircraft, however he had not received a tail wheel endorsement (required by FAR 61.31[I]). The pilot noted in his written report to the NTSB that there were no preaccident mechanical anomalies with the airplane.