Incident Details
The airplane was initiating a departure from runway 16 for a local aerial application flight when the pilot reported hearing a 'loud bang.' Immediately after, the right rudder pedal 'fell to the floor.' The airplane veered left, exited the runway, ground-looped, and came to rest upright. The sequence of events resulted in a loss of directional control during the takeoff roll.
Investigation Findings
Postaccident examination of the airplane revealed that the right rudder cable had separated at the aft fairlead. The separated cable was sent to the NTSB Materials Laboratory for detailed analysis. Laboratory examination showed that the individual strands of the cable exhibited a flat and shiny appearance, characteristic of wear. The wear was concentrated primarily on one side of the cable, extending approximately 90 degrees around the cable's circumference, indicating contact with the fairlead over time.
Service Information
Air Tractor had previously issued a service letter on August 27, 1999, addressing rudder cable wear at the aft fairlead on the AT-802 and AT-802A models. The service letter advised operators that a new cable design was available, incorporating a stainless steel sleeve crimped to the cable in the area of the fairlead to mitigate wear. The operator of the accident airplane was aware of this service letter but had not replaced the rudder cables prior to the incident.