On September 12, 1999, about 1620 Eastern Daylight Time, a North American T6-G, N7767C, operated under an experimental certificate, was substantially damaged when it struck trees while on approach to a private grass runway, in Falmouth, Kentucky. The certificated commercial pilot owner was fatally injured, and a passenger sustained minor injures. Visual meteorological conditions prevailed and no flight plan had been filed for the flight that departed the Mount Sterling-Montgomery County Airport (IOB), Mount Sterling, Kentucky. The personal flight was conducted under 14 CFR Part 91. In a telephone interview, the passenger stated he had flown with the pilot in the accident airplane about 4 or 5 times, and in a SNJ-2 model about 20 times. They had departed the pilot's private airstrip, about 1330, and flew to IOB. The passenger described the return flight from IOB as uneventful. The pilot flew over the field and observed the windsock was straight down the runway, favoring a landing from the north. The passenger said the approach seemed normal; however, he was seated in the rear seat and "could not see anything." He then felt an impact and assumed the airplane had struck a tree. The airplane's right wing dropped 20 to 30 degrees, and he could see the ground approaching. The airplane then impacted the ground. Additionally, the passenger stated the engine sound was constant throughout the approach, with no abrupt power changes. A witness who observed the airplane from a house adjacent to the runway stated the airplane's landing gear struck the tops of the trees. She heard branches breaking, and saw leaves "flying." The airplane's right wing struck the ground, and the airplane flipped over. Examination of the wreckage by a Federal Aviation Administration Inspector did not reveal any pre-impact malfunctions of the airframe or engine. The airplane impacted the tops of about 50 foot tall trees, approximately 274 feet from where the airplane came to rest. The airstrip was about 2,200 feet long. The pilot's logbook was not located. He reported 3,600 hours of total flight experience on his most recent application for an FAA second class medical certificate, which was issued on June 11, 1999.