On October 19, 2002, about 1150 mountain standard time, a homebuilt Rotorway 162F, N162AZ, collided with terrain during a forced landing about 5 miles south of Ryan Field Airport, Tucson, Arizona. The pilot/owner was operating the helicopter under the provisions of 14 CFR Part 91. The private pilot, the sole occupant, was not injured; the helicopter was destroyed. Visual meteorological conditions prevailed and a flight plan had not been filed. The personal local flight originated about 1140 from Ryan Field. In a statement collected by a Federal Aviation Administration (FAA) inspector, the pilot reported that while performing pattern and ground reference maneuvers, the helicopter experienced a mechanical malfunction. The pilot executed an autorotation and contacted high vegetation with the helicopter's right skid, resulting in the helicopter rolling to the left and impacting terrain. The pilot's disposal of the helicopter in a waste dump prior to examination prevented the FAA from performing an inspection to determine the nature of the mechanical malfunction. In a telephone interview with a National Transportation Safety Board investigator, the pilot reported that the secondary shaft broke in half, resulting in a loss of power to the helicopter's main rotor. The pilot was aware of the advisory service bulletin issued by the manufacturer suggesting replacement of the secondary shaft assembly, but had not complied. Beginning in May 1995, the kit manufacturer released four separate Advisory Bulletins (A-23, A-26, A-32 and A-34) addressing installation, inspection, and shaft design change issues. Concerned about shaft failures, the most recent advisory bulletin at the time of the accident, issued May 2002, recommended replacement of the standard 30 mm secondary shaft with an upgraded 35 mm shaft. After the accident, and following a secondary shaft failure accident in a Rotorway Exec 90 on February 4, 2003, the manufacturer issued a Mandatory Compliance Bulletin (M-21). The bulletin required owners of all Exec 90 and Exec 162F helicopters to comply with a periodic inspection of the secondary drive assembly at 100-hour intervals. The bulletin further mandated immediate inspection of the secondary shaft if the helicopter had previously sustained a tail rotor strike. Despite repeated attempts, the Safety Board was unable to follow-up with the pilot/owner concerning the maintenance history of the helicopter or obtain a completed NTSB 6120.1/2 form.