Accident Details
On July 21, 2010, at 1300 central daylight time, an Air Tractor AT-401, registration N45297, experienced a loss of engine power while operating under 14 Code of Federal Regulations Part 137 as an agricultural spraying flight. The airplane had departed Walnut, Illinois, about 1230 for a local flight. Visual meteorological conditions prevailed and no flight plan was filed. The forced landing occurred in a cornfield near Toulon, Illinois, resulting in substantial damage to the aircraft. The commercial pilot, the sole occupant, was not injured.
Pilot Report
According to the pilot, he had completed his last spray run and was pulling out of the field at an altitude of about 200 feet above ground level when “the cylinder cracked” and oil covered the windshield. The pilot then flew toward a satellite airstrip located approximately 4 to 6 miles away. He reported that the airstrip was short, and because his visibility was severely limited by oil on the windshield, the airplane overran the runway and nosed over after contacting a ditch.
Aircraft Information
The accident aircraft was an Air Tractor AT-401, serial number not specified in the source. It was equipped with a Pratt and Whitney R-1340 series reciprocating engine. At the time of the accident, the airframe behind the cockpit was found to be bent, and the #2 cylinder had a crack extending from near the front spark plug to the rear spark plug.
Relevant Maintenance Directives
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 mandated initial and repetitive visual and fluorescent penetration inspections of cylinders for head cracking, prompted by reports that such cracking could result in engine power loss, forced landing, and airframe damage. For cowled and baffled installations, the AD required visual inspections at intervals not exceeding 250 hours time in service since the last inspection. For all other installations, the interval was not to exceed 100 hours. A post-accident examination of the airplane’s logbooks by an FAA inspector revealed that 18 hours of time in service had elapsed since the last required inspection of the cylinders per AD 99-11-02.
Examination Conclusions
The source provides no explicit statement of probable cause for the accident. The inspection identified a cracked #2 cylinder as a likely source of engine power loss, and the subsequent forced landing and nose-over were attributed to the emergency situation and obscured visibility.