Incident Details
According to the pilot, while on short final to the airstrip, the aircraft encountered a windshear and downdraft. The pilot added power to initiate a go-around. During this maneuver, the plastic control wheel on the left side of the cockpit broke into two sections at its midpoint. The aircraft then struck the ground hard and veered off the runway.
Pilot Actions
The pilot stated that after the left control wheel failed, he attempted to control the aircraft by grabbing the wheel on the right side of the cockpit. However, the aircraft hit the ground and he lost directional control.
Maintenance History
The plastic control wheels installed in this model are subject to a recurring Airworthiness Directive (AD 69-22-2). This AD mandates repetitive dye penetrant inspections at each annual inspection to detect cracks in the center of the wheel. Review of the maintenance records showed that the control wheel had been inspected in accordance with the AD at the last annual inspection.
Examination Findings
A microscopic examination of the fracture face revealed no evidence of dye penetrant. This indicates that the crack did not exist at the time of the last inspection.
Conclusion
The investigation documented the sequence of events and the results of the post-accident examination. No probable cause was determined from the available information.