On July 16, 1997, about 1245 eastern daylight time, N52120, a Cessna 177RG, owned and operated by the private pilot, sustained substantial damage after impacting rough terrain about two miles west of the departure end of runway 23, at the McGhee Tyson Airport, Knoxville, Tennessee. The pilot and two passengers were not injured. Visual meteorological conditions existed and a visual flight rules (VFR) flight plan was filed. The flight was conducted under the provisions of Title 14 CFR Part 91, with an intended destination of Farmington, Missouri. The pilot stated to the FAA that he did a preflight inspection and found no discrepancies. He said that shortly after takeoff the engine started running roughly and subsequently stopped. The pilot initiated an emergency landing into an open field, and encountered rough terrain. Visual examination of the airplane by a FAA Inspector revealed the oil dipstick to be loose and isolated areas of oil wetness in the vicinity of the #2 cylinder base and around the right rear accessory section. Oil was also found on the lower right hand windshield and on the nose landing gear doors and down 50% of the belly of the fuselage. Attempted rotation of the crankshaft was limited to approximately 90 degrees of travel, the #3 and #4 pistons were not moving, continuity to the rear accessory section was not established. The engine was subsequently removed from the aircraft for closer examination. All fluid carrying hoses and lines were intact and secure. The oil cooler was not damaged. The oil drain was closed. Upon removal of the engine baffles, epoxy adhesive was noted at the forward crankcase thru-stud on the lower left side, and at the #2 cylinder hold-down nut, bottom forward position. Additional epoxy adhesive was also noted on the top rear section of the crankcase split. The engine was subsequently boxed and shipped to Textron Lycoming for further examination. On November 19, 1997, an engine teardown and examination was accomplished at the Textron Lycoming facility in Williamsport, Pennsylvania. Present were representatives from the FAA and Lycoming. Visual inspection of the engine assembly revealed a crack located at the #4 cylinder mount pad, between the lifter bosses was attributed to secondary internal damage. All engine accessory components were removed and inspected, no anomalies were noted. The propeller system governor contained ferrous metal particles; the spline drive was intact. The rear accessory section was removed which revealed a broken tooth on the crankshaft gear; correspondingly there were two broken teeth on the left-hand idler gear. The oil pump was inspected and exhibited signs of hard object passage while in operation. The pump gears and shaft were still intact. The oil suction screen was partially obstructed with various size ferrous metals. The oil filter element was inspected and contained small size ferrous particles. No objects foreign to the engine were identified. Disassembly of the engine power section revealed heat damage emanating progressively from the rear of the engine toward the front. The aft section of the crankshaft at the rear connecting rod assemblies was highly distressed and exhibited severe heat damage. The #4 and #3 connecting rods were detached, the yoke portion of both rod assemblies were fragmented and destroyed, the affected parts were blackened from heat. Damage to the #2 connecting rod was moderate to severe; bearing material was distressed and extruded. The #1 connecting rod was slightly damaged from heat. The main crankshaft bearing surfaces were basically not affected. However, the main bearing surfaces did exhibit slight metal particle embedment. The distribution of damage directly corresponded with the direction of oil flow, within the lubrication system. The oil passages from the origin of the oil pump to the crankshaft main and rod journals were checked and found clear of obstructions.