HISTORY OF FLIGHTOn April 30, 2014, about 1055 Pacific daylight time, an experimental amateur-built Pulsar XP, N452PC, sustained substantial damage on landing at Bremerton National airport (PWT), Bremerton, Washington. The pilot-owner was not injured. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the flight. According to the pilot, he was also the builder of the kit airplane. The airplane was based at PWT. The pilot took off about 1000 for a local flight. While airborne, he received a radio call from Avian Flight Center, a fixed base operator (FBO) at PWT. FBO personnel informed him that they had been made aware that a passer-by had seen something fall from an airplane, which was subsequently identified as a nose landing gear (NLG) wheel and tire assembly, and that the FBO believed that the NLG components possibly belonged to N452PC. The pilot returned to PWT and conducted a flyby, to allow the FBO personnel to examine the airplane. They confirmed that N452PC had lost its NLG wheel and tire assembly. The FBO then coordinated with the pilot to postpone landing until the airport could be closed to other traffic, and fire/rescue personnel could be present. After waiting about 30 minutes, the pilot was given permission to land. He landed with full flaps, as slowly as he could. The airplane landed normally, settled on the NLG strut, and stopped on the runway. PERSONNEL INFORMATIONFederal Aviation Administration (FAA) records indicated that the pilot held a private pilot certificate with an airplane single engine land rating. According to information provided by the pilot, he had approximately 884 total hours of flight experience, including approximately 811 hours in the accident airplane make and model. His most recent flight review was completed in June 2012, and his most recent FAA third-class medical certificate was issued in April 2003. The pilot was operating the airplane in accordance with the FAA sport pilot medical certification criteria. AIRCRAFT INFORMATIONAccording to the pilot, he completed construction of, and first flew, the airplane in 1998, and had put about 811 hours on it since then. The airplane was equipped with a Rotax 912UL series engine. About 2 days after the accident, the pilot was informed by another Pulsar operator that there were five previous events of NLG separations on Pulsar airplanes. Reportedly, a new NLG fitting had been designed by another owner to eliminate the underlying problem, which was traced to a corroded attach bolt that was difficult to access or inspect. Also reportedly, these failures only affected Pulsar "Series 1" airplanes, which was the same model as the pilot's airplane. Because the airplane kit manufacturer was no longer in business, the investigation did not obtain any additional information regarding the NLG modification. METEOROLOGICAL INFORMATIONThe 1055 PWT automated weather observation included winds from 030 degrees at 8 knots, visibility 10 miles, clear skies, temperature 21 degrees C, dew point 6 degrees C, and an altimeter setting of 30.38 inches of mercury. AIRPORT INFORMATIONAccording to the pilot, he completed construction of, and first flew, the airplane in 1998, and had put about 811 hours on it since then. The airplane was equipped with a Rotax 912UL series engine. About 2 days after the accident, the pilot was informed by another Pulsar operator that there were five previous events of NLG separations on Pulsar airplanes. Reportedly, a new NLG fitting had been designed by another owner to eliminate the underlying problem, which was traced to a corroded attach bolt that was difficult to access or inspect. Also reportedly, these failures only affected Pulsar "Series 1" airplanes, which was the same model as the pilot's airplane. Because the airplane kit manufacturer was no longer in business, the investigation did not obtain any additional information regarding the NLG modification. WRECKAGE AND IMPACT INFORMATIONThe airplane came to rest upright, about 150 feet beyond the numbers of runway 2, just left of the centerline. The NLG strut and lower cowl were crushed and scraped, both blades of the wood propeller were fractured, and the firewall was fractured in at least two locations. Examination of the wreckage by FAA personnel revealed that the pivot shaft that enabled the nose landing gear (NLG) wheel and tire assembly to caster for directional control had fractured, and that fracture allowed the NLG fork to depart the airplane during takeoff. Examination of photographs of the fracture end of the pivot shaft by the investigator-in-charge and a metallurgist at the NTSB materials laboratory indicated that the fracture patterns were consistent with reversed bending (bi-directional) fatigue. According to the builder/owner/pilot, the shaft was a solid 4130 steel rod that nested and was welded into the tubular steel nose gear leg, and on which the NLG fork assembly was mounted and rotated. The shaft fractured just inside the lower end of the NLG leg tube.