On August 16, 2013, approximately 1815 eastern daylight time, an experimental light sport Fetterman Firestar II, N598LF, was substantially damaged during a forced landing at Numidia Airport (8PA0), Numidia, Pennsylvania. The certificated sport pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight, which was originating at the time of the accident. The flight was operated under the provisions of Title 14 Code of Federal Regulations Part 91. The pilot stated that prior to departing on the accident flight, he drained the airplane's fuel tank and added 8 gallons of 92-octane automotive fuel, premixed with oil to manufacturer's specifications. He subsequently drained fuel from the gascolator to check for the presence of water, and stated that the sample contained none. The pilot performed a run-up check of the engine by increasing power to 4,000 rpm for about four minutes. During this time, he stated that the engine sounded "terrific," and that a magneto check revealed no anomalies. He then taxied the airplane to the end of the turf runway, performed a second run-up, and stated that all engine indications were within parameters. The pilot applied engine power to initiate the takeoff, and the airplane lifted off the runway and climbed to about 300 feet above ground level. The engine subsequently began to "surge," fluctuating between 6,200 rpm and about 4,500 rpm, and the pilot elected to return to the airport. On final approach, the pilot reduced engine power to idle and the engine subsequently experienced a total loss of power. Upon touchdown on the runway, the right main landing gear wheel departed from the gear leg, the gear leg dug into the turf, and the airplane nosed over and came to rest inverted. The pilot held a sport pilot certificate with a rating for airplane single engine land. He reported 238 total hours of flight time, of which 72 hours were in the accident airplane make and model, and reported that he had flown the accident airplane 3 hours in the year previous to the accident. The airplane was manufactured in 1997, and was issued a Federal Aviation Administration airworthiness certificate in 2006. It was equipped with a Rotax 503 DIDC, 52 hp reciprocating engine. Its most recent annual inspection was completed on May 3, 2013. At the time of the accident, the airplane and engine had accrued 72 total hours of flight time. Postaccident examination by a Federal Aviation Administration inspector revealed substantial damage to the airframe's tubular structure, as well as the tail boom and left wing. Examination of the right main landing gear wheel revealed a fracture of the bracket that connected the wheel axle to the landing gear leg. Continuity was confirmed from the cockpit area to the flight control surfaces. No examination of the engine was performed. The pilot reported that he believed the engine surging was the result of a fuel flow issue. He stated that several weeks after the accident, he examined the engine's carburetor bowls, and found that neither contained any fuel. The fractured wheel axle bracket was sent to the NTSB Materials Laboratory for analysis. Examination indicated that the bracket fractured near a weld. The fracture surface displayed a flat, thumbnail-shaped region near one of the toes of the weld; a signature consistent with a fatigue crack. The fatigue crack was approximately 0.2 inches in the circumferential direction and extended through approximately 70 percent of the wall thickness at the joint.