On August 25, 1996, at 1709 central daylight time, a Mooney M20J, N4538H, registered to and operated by a private owner under Title 14 CFR Part 91, sustained substantial damage during a forced landing following a loss of engine power near Lubbock, Texas. The private pilot was not injured and the sole passenger received minor injuries. Visual meteorological conditions prevailed at the accident site. The flight was on an IFR flight plan and the flight originated from Lubbock, Texas, at 1657. During interviews, conducted by the investigator-in-charge, on the enclosed ATC data, and the Pilot/Operator Report, the following information was revealed. The flight was en route to Childress, Texas; however, the pilot changed the destination to the Lubbock International Airport, Lubbock, Texas, due to rain and low ceilings at Childress. At Lubbock the pilot had the airplane refueled, filed an IFR flight plan to Las Cruces, New Mexico, and departed on runway 17R with a clearance to 10,000 feet MSL. At 1659, the pilot was cleared to contact departure control (frequency 119.2) and reported on the departure control frequency as the flight continued the climb to cruise. Between 5,000 feet MSL and 6,000 feet MSL, at approximately 1706, the pilot contacted the controller and "declared an emergency due to his engine cutting out and he had a little manifold pressure/RPM" The pilot was cleared for the landing at Lubbock; however, the pilot stated that he was going to try to land at Reese AFB. The controller told the pilot that Reese was to the right of the airplane about 3 to 4 miles and the pilot reported that he had Reese airport in sight. Subsequently, the pilot reported that he could not make the airport and would land the airplane at the present position. The airplane was landed in a cotton field and during the landing roll the right main gear collapsed and the right wing separated from the airframe at the forward attachment point. Following the recovery of the airplane from the accident site, the airplane was examined at Lubbock, Texas by the FAA inspector. During the inspection, it was found that both of the magneto retention nuts that hold the single drive magneto to the engine had loosened and the magneto was disengaged from its drive gear. A review of the maintenance records by the investigator-in-charge, and the FAA inspector, revealed that the magneto was overhauled and reinstalled during the engine overhaul on April 12, 1996. The airplane had flown 120 hours since the installation. According to the FAA inspector, the "magneto was installed with the correct hardware."