On April 16, 2004, approximately 1040 central daylight time, a Cessna 175B single-engine airplane, N8172T, was substantially damaged during a forced landing following a loss of engine power during cruise flight near Locust Grove, Oklahoma. The private pilot and the passenger sustained minor injuries. The airplane was owned and operated by Elite Aircraft Sales Incorporated, of Boca Raton, Florida. No flight plan was filed for the cross-country flight that originated at the Charles W. Baker Airport (2M8), near Millington, Tennessee, about 0930, and was destined for the Claremore Regional Airport (1O7), near Claremore, Oklahoma. Visual meteorological conditions prevailed for the personal flight conducted under 14 Code of Federal Regulations Part 91. A Federal Aviation Administration (FAA) inspector, who responded to the accident site, performed an on-scene examination of the airplane and interviewed the pilot. The pilot stated that while in cruise flight, he smelled "fumes" and the engine began to "shudder." The pilot added that the engine gauges indicated normal readings; however, the engine continued to shudder and the oil pressure dropped to zero within a few seconds and it began to lose power. The pilot was unable to maintain altitude and elected to perform a forced landing to an open field. Upon touchdown, the airplane rolled about 78 feet before it nosed over, coming to rest in the inverted position. External examination of the airplane revealed oil streaks over the left and right side of the engine cowling. The fuselage, vertical stabilizer and rudder sustained structural damage. Examination of the engine revealed that the recently installed generator had backed off the accessory section of the engine approximately 1/4-to-3/8 of an inch, which allowed engine oil to escape. Two of the three bolts that secured the generator to the engine were missing. One bolt remained partially attached, and the nut was backed off approximately 3/4 of an inch. According to the maintenance manual, proper installation of the generator required it to be installed with an elastic and a plain washer. However; a plain washer, star washer, and a second plain washer were installed instead. A review of the engine logbooks revealed that the generator was installed on February 24, 2004, during the aircraft/engine annual inspection with an overhauled unit at a total aircraft time of 2,327.6 hours. The airplane accrued an additional 37 hours after the generator was installed. Several attempts were made to obtain a completed NTSB Form 6120.1/2 from the operator.