Accident Summary
During an aerial-application flight, the pilot was spraying at approximately 6 feet above ground level when the engine began running rough and then quit. The pilot executed an emergency landing in a muddy soybean field. The aircraft slid to a stop, sustaining damage to the right lower wing and right landing gear.
Aircraft Examination
A postaccident examination of the airplane revealed that the number 8 cylinder head had separated from the cylinder barrel between the second and third cooling fins. This condition is identified in Pratt and Whitney Airworthiness Directive (AD) 78-08-07.
Maintenance and AD Compliance
The AD requires a recurring visual inspection of the cylinder at either 150-hour or 100-hour intervals. Cylinders that had been ultrasonically tested prior to installation on the engine were to be inspected at 150-hour intervals, while those not ultrasonically tested required inspection at 100-hour intervals. According to the aircraft maintenance records, the airplane had accumulated 99.8 hours time in service since the last inspection. It is not known if the failed cylinder had undergone ultrasonic inspection prior to installation.
Impact and Damage
The forced landing resulted in damage to the right lower wing and right landing gear. The aircraft came to rest in the soybean field after sliding to a stop.