On February 11, 1996, at 1730 central standard time, a Cessna 172K, N7358G, was substantially damaged during a forced landing near Hedley, Texas. The instrument rated private pilot and his passenger were not injured. The airplane was being operated by the owner as a personal flight under Title 14 CFR Part 91. The flight departed Memphis, Texas, at 1715. Visual meteorological conditions prevailed for the cross country flight for which a flight plan was not filed. The pilot reported that he was returning to Amarillo, Texas, from Memphis, Texas. The pilot stated that, "the engine suddenly started making a clanging noise, about five seconds later, a big bang, [and] the propeller stopped, straight up and down." An emergency landing to a hay field was made. During the landing the "front wheel caught" in some sandy soil and the airplane flipped over. The engine was examined at Horton Aero Services, Lubbock, Texas, on February 15, 1996. The examination revealed that one connecting rod bolt nut from the #4 connecting rod was off the bolt and found loose in the crankcase. The #4 piston pin boss was broken and the piston pin was found loose in the crankcase. The #4 connecting rod bearings were destroyed. The connecting rod bolts on the #1 and #2 connecting rods were not at the prescribed torque. The last major engine overhaul was 35 hours prior to the accident.