On September 20, 2008, about 0930 central daylight time, an experimental Powrachute Pegasus powered-parachute, N7084L, piloted by a flight instructor and student pilot, sustained minor damage when the nose landing gear collapsed during landing at Mark's Park and Airfield (3WN4) near New London, Wisconsin. The student pilot was seriously injured during the event. The flight instructor was not injured. The dual instructional flight was being conducted under 14 Code of Federal Regulations Part 91 without a flight plan. Visual meteorological conditions prevailed at the time of the accident. The local flight took off about 0830. The pilot's were practicing touch-and-goes at time of the accident. The student pilot reported that he had observed 5 or 6 touch-and-goes from the rear seat, as the flight instructor flew from the front seat. He controlled the throttle during this initial portion of the flight. He and his instructor then switched positions, with the student pilot flying from the front seat and the instructor observing from the rear seat. He completed another 5 or 6 touch-and-goes as the flying pilot and "everything went perfect." However, when he touched down on the final landing, the nose wheel support failed causing the aircraft to ground loop. During the accident sequence, the steering bar struck him in the chest. He was hospitalized for treatment of the serious injuries sustained in the accident. A post accident examination revealed that the nose wheel front fork support had failed at a welded joint immediately forward of the airframe attachment bolt. Visual examination of the weld indicated a lack of penetration at the joint. In addition, the weld material did not appear to be of a uniform thickness. Subsequent to the accident, the manufacturer issued a service bulletin advising owners of two failures of the welded joint on the front fork support. The manufacturer recommended that supports be replaced with a Tungsten Inert Gas (TIG) welded support. The original support may have been Metal Inert Gas (MIG) welded without proper penetration, according to the bulletin.