CHI07LA221

The pilot stated that 15 minutes into the flight the airplane began to lose airspeed. The flight was 300 to 500 feet above ground level en route to the assigned spray field at the time. He noted that although he was at full throttle, the airplane continued to lose airspeed. He subsequently observed oil on the right side of the engine cowling. The pilot recalled banking left to avoid an interstate highway. He commented that the airplane "quit flying" just prior to the landing. The airplane came to rest upright in a corn field. A post impact fire consumed approximately one-half of the aircraft. A post accident inspection revealed that the number 3 engine cylinder head had separated into two sections. Examination of the fracture faces revealed features consistent with a fatigue failure. The failure initiated at the root of the cylinder head thread engaged with the uppermost barrel thread. Engine maintenance records indicated that the engine had accumulated approximately 7,495 hours total time, with about 615 hours since overhaul.

On July 22, 2007, about 1025 central daylight time, a Grumman G-164A airplane, N9828, piloted by a commercial pilot, was destroyed during a forced landing following a loss of engine power near Moline, Illinois. The agricultural application flight was being conducted under 14 CFR Part 137 without a flight plan. Visual meteorological conditions prevailed at the time of the accident. The pilot sustained serious injuries. The local flight had departed Davenport Municipal Airport (DVN), Davenport, Iowa, approximately 1010.

The pilot stated that 15 minutes into the flight the airplane began to lose airspeed. The flight was 300 to 500 feet above ground level en route to the assigned spray field at the time. He noted that although he was at full throttle, the airplane continued to lose airspeed. He subsequently observed oil on the right side of the engine cowling. The pilot recalled banking left to avoid an interstate highway. He commented that the airplane "quit flying" just prior to the landing. The airplane came to rest upright in a corn field. A post impact fire consumed approximately one-half of the aircraft.

A post accident inspection revealed that the number 3 engine cylinder had failed. The cylinder head had separated into two sections. Examination of the fracture faces revealed arced crack arrest marks and ratchet marks consistent with fatigue. The orientation of the marks suggested that the fatigue failure initiated at the root of the cylinder head thread engaged with the uppermost barrel thread.

Engine maintenance records noted that the engine was overhauled in October 1993. Detailed overhaul records were no longer available. Markings on the failed cylinder suggested that it had been re-chromed consistent with the cylinder being overhauled at the time of the engine overhaul. The records indicated that the engine had accumulated approximately 7,495 hours total time, with about 615 hours since overhaul.