On July 21, 2010, at 1300 central daylight time, an Air Tractor AT-401, N45297, sustained substantial damage during a forced landing to a cornfield after a loss of engine power near Toulon, Illinois. The commercial pilot was not injured. The 14 Code of Federal Regulations Part 137 agricultural spraying flight departed Walnut, Illinois, about 1230 on a local flight. Visual meteorological conditions prevailed and no flight plan was filed. The pilot reported that he had made his last spray run and pulled out of the field. The airplane was about 200 feet above ground level when “the cylinder cracked” and oil covered the windshield. The pilot flew to the satellite airstrip about 4 – 6 miles away. The pilot reported that the airstrip was short, and because he could not see very well out of the oil covered windshield, the airplane overran the runway and nosed over when it hit a ditch. The inspection of the airplane revealed that the airframe behind the cockpit was bent. The # 2 cylinder of the engine had a crack from the area near the front spark plug to the rear spark plug. On July 19, 1999, the Federal Aviation Administration (FAA) issued Airworthiness Directive (AD) 99-11-02, for Pratt and Whitney R-1340 series reciprocating engines. The AD required initial and repetitive visual and florescent penetration inspections of cylinders for head cracking. This was prompted by reports of cylinder head cracking which can result in engine power loss, forced landing, and damage to the aircraft. For cowled and baffled installations, the AD required that a visual inspection of the cylinders be accomplished at intervals not to exceed 250 hours time in service since the last inspection. For all other installations, the AD required that a visual inspection of the cylinders was to be accomplished at intervals not to exceed 100 hours time in service since the last inspection. A FAA inspector examined the airplane’s logbooks and reported that 18 hours of time in service had elapsed since the last inspection of the cylinder per AD 99-11-02.