On March 23, 1997, at 0849 hours Pacific standard time, an experimental, amateur built, Zenair 601, N4073T, impacted terrain in a pasture near Penn Valley, California. The aircraft was destroyed and the private pilot was fatally injured. Visual meteorological conditions prevailed for the personal flight which departed from Nevada County Airport at Grass Valley, California, about 0830. According to an Federal Aviation Administration (FAA) inspector, a witness who lives about 1 mile from the accident site reported that the aircraft's engine was "cutting out" as the aircraft flew over his location. Another witness, inside his home near the accident site, did not hear the engine at all; he reported hearing only a "whoosh" and a "thump." The pilot purchased the aircraft August 30, 1996. The pilot's son told the FAA inspector that this was his father's first flight in the aircraft and that he had not had any checkout. The previous flight in the pilot's logbook was November 13, 1996. The last maintenance entry in the aircraft logbook was an annual inspection on September 7, 1995. Later entries in the logbook were made by the pilot's son, who was not a certificated mechanic or repairman, after the accident, and do not contain an approval for return to service. A toxicology analysis performed by the FAA's Civil Aeromedical Institute detected the drug Diphenhydramine in the pilot's blood (0.062 ug/ml, ug/g) and urine (0.160 ug/ml, ug/g).