20010927031359A

(-23) The engine stopped operating during a turn while agricultural spray operations were being conducted. The pilot continued the turn into the wind and tried to make the engine operate by turning on the fuel boost pump. There was no response from the engine and the pilot landed in a cotton field with a circular irrigation and planting pattern. The curve in the crop rows pulled the airplane into a turn to the right, collapsing the left main gear and bending the left wing upward just outboard of the wing strut. The drive train at the rear of the engine had become disconnected. The engine will undergo a supervised teardown at the teledyne Continental factory. (.4) the pilot was maneuvering the agricultural airplane to enter a field and commence spraying, when at 120 feet AGL, the engine lost power. The pilot attempted to restart the engine; however, the engine did not restart. During the ensuing forced landing, the airplane contacted circular rows of cotton, before coming to rest upright. The engine was examined at the manufacturer's facility and silicon sealant was observed on the base flanges of the #1, #2, #4, and #6 cylinders and on the crankcase mating surfaces. Frettin g was observed on the base flanges of the cylinders, on the mating surface of the crankcase halves, and on the main bearing bosses. The #2 main bearing was observed fragmented and the bearing's bore was cracked and damaged. Additionally, it was observed that the crankshaft was fractured between the #2 main bearing and #3 crankshaft cheek. According to a tcm metallurgist, the fatigue fracture's origin was determined to be at the aft radius of the #2 main bearing. The silicon sealant prevented proper torqueing of the bolts that mate the crankcase halves and led to vibration at the crankcase mating surfaces. The #2 main bearing then shifted and failed, resulting in a loss of engine power.