On December 14, 1996, at 1000 central standard time, an Ercoupe 415-D, N87226, was substantially damaged during a forced landing near Amarillo, Texas. The airplane was registered and operated by a private owner under Title 14 CFR Part 91. The private pilot and his passenger were not injured. Visual meteorological conditions prevailed for the personal flight for which no flight plan was filed. The flight originated from the Tradewinds Airport in Amarillo, Texas, approximately 10 minutes prior to the accident, for a flight to Dumas, Texas. The pilot was interviewed by an FAA inspector at the accident site. According to the pilot, the engine lost power without warning as he retarded the throttle to 2,250 RPM while leveling at 5,500 feet MSL. The pilot, who was seated in the right seat, attempted without success to restart the engine, and elected to execute a forced landing to a road. The traffic conditions on the road prevented the use of the road for the forced landing and the pilot elected to use a "mesquite covered field" adjacent to the road. The pilot further stated that besides being covered with mesquite trees, "the field selected turned out to be rough and uneven." The nose landing gear collapsed and both wing spars sustained structural damage during the landing roll. The owner of the airplane, who was a passenger on this flight, stated that the 1946 vintage airplane was purchased approximately 3 months earlier, after the airplane had been restored. An NTSB Form 6120.1/2 was not received from the pilot; however, a passenger statement and a comprehensive narrative were received from the owner of the aircraft. Post-accident examination of the engine by the FAA inspector revealed that the head for the exhaust valve for the #1 cylinder had separated from the valve stem resulting in internal damage to the cylinder, piston, intake valve, and both push rods.