On October 27, 2004, approximately 1000 central daylight time, a McCulloch Aircraft Corporation J-2 single-engine gyrocraft, N62SJ, sustained substantial damage during cruise flight following an in-flight separation of the engine exhaust stack. The gyrocraft was registered to and operated by the pilot. The private pilot, sole occupant of the gyrocraft, was not injured. Visual meteorological conditions prevailed and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 personal flight. The cross-country flight originated from the Harrell Field Airport, near Camden, Arkansas, approximately 5 minutes prior, and was destined for the Magnolia Municipal Airport, near Magnolia, Arkansas. The 605-hour pilot reported in a written statement that during cruise flight, the gyrocraft started to vibrate and he shut the engine down. Subsequently, the pilot initiated an autorotation to a highway and landed without further incident. Examination of the gyrocraft by an Federal Aviation Administration (FAA) inspector, who responded to the site of the accident, revealed the right tailboom was partially separated. Examination of the gyrocraft by the pilot revealed that the left rear exhaust stack had separated at the flange and had struck the propeller. The pilot also reported that the gyrocraft's most recent annual inspection was performed on May 22, 2003, and had accumulated a total of 99 hours of flight since the inspection.