On December 8, 2020, about 1030 mountain standard time, a Piper PA-12, N2554M, was involved in an accident near Spearfish, South Dakota. The private pilot and a passenger were uninjured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 maintenance test/check flight. After completing an annual inspection, maintenance personnel performed post-inspection engine run-ups, then turned the fuel selector to the OFF position. The pilot arrived at the maintenance facility with a passenger to perform a post-maintenance test/check flight. The pilot stated that the left fuel tank was ½ full and the right fuel tank was ¾ full, and that he positioned the fuel selector to the right fuel tank. Following an engine run-up, he initiated takeoff, and the airplane climbed to about 70 ft above the runway. The airplane lost engine power for a few seconds, regained power for a few more seconds, and then lost total power. The pilot lowered the airplane’s nose to increase airspeed, and the airplane continued to descend. He tried to flare the airplane, but the airplane landed hard on the runway, resulting in substantial damage to the fuselage tubular structure. A postacccident engine run revealed no mechanical anomalies that would have precluded normal operation.