What happened
While on short final approach to the airstrip, the pilot encountered windshear and a downdraft. In an attempt to execute a go-around, the pilot increased power; however, the plastic control wheel on the left side of the cockpit broke into two sections at the middle.
Following the structural failure of the control wheel, the pilot attempted to maintain control by grabbing the right-side control wheel. Despite this effort, the aircraft struck the ground with significant force and veered off the runway. The pilot was not injured.
The investigation
The investigation focused on the integrity of the plastic control wheels, which are subject to a recurring airworthiness directive (69-22-2). This directive requires repetitive dye penetrant inspections for cracks in the center of the wheel during each annual inspection.
Maintenance records indicated that the control wheel had been inspected according to the airworthiness directive during the most recent annual inspection. A microscopic examination of the fracture face was performed, which revealed no evidence of dye penetrant. This finding indicated that the crack was not present at the time of the last scheduled inspection.