Incident Overview
An agricultural pilot was engaged in spraying cotton when the aircraft entered a 60-degree bank. During the maneuver, the pilot observed that the ailerons were ineffective. In response, power was reduced and an attempt was made to level the wings using right rudder. However, the left wing subsequently contacted the ground, followed by the left main landing gear. The aircraft then tumbled multiple times before ending up inverted.
Post-Accident Examination
Following the accident, a detailed examination of the flight controls was conducted. Investigators discovered that a bolt within the aileron torque tube had fractured. This failure rendered the ailerons inoperable. Further metallurgical analysis of the fractured bolt revealed evidence of low-stress, multiple-origin fatigue cracking.
Findings
The investigation identified the fractured aileron torque tube bolt as the component that disabled the aileron control system. The fatigue cracking observed in the bolt indicated a progressive failure mechanism. No other anomalies in the aircraft structure or systems were reported.
Conclusion
The event occurred as a direct result of the structural failure of the aileron torque tube bolt, which led to loss of lateral control. The pilot's actions to reduce power and apply rudder were not sufficient to prevent ground contact given the compromised control system.