FTW00LA030

The airplane was departing from runway 16 for a local aerial application flight, when the pilot heard a 'loud bang,' and 'the right rudder pedal fell to the floor.' The airplane veered to the left, exited the runway, ground-looped, and came to rest upright. Postaccident examination of the airplane revealed that the right rudder cable separated at the aft fairlead. Examination of the rudder cable by the NTSB Materials Laboratory revealed that the individual separated strands of the cable had a flat and shiny appearance, indicative of wear. The wear was primarily on one side of the cable, extending around 90 degrees of the cable's circumference. Air Tractor issued a service letter on August 27, 1999, advising operators of rudder cable wear at the aft fairlead on the AT-802 and AT-802A. The service letter stated that a new cable, which incorporated a stainless steel sleeve that is crimped to the cable in the area of the fairlead, was available. The operator was aware of the service letter, but had not replaced the rudder cables.

On October 11, 1999, at 1700 central daylight, time an Air Tractor AT-802A agricultural airplane, N6044A, was substantially damaged when it exited the runway and ground looped during the takeoff roll at the Lamesa Municipal Airport, near Lamesa, Texas. The airplane was registered to a private individual and operated by the Glenn Hogg Flying Service Inc., of Lamesa, Texas. The commercial pilot, sole occupant of the airplane, was not injured. Visual meteorological conditions prevailed for the 14 Code of Federal Regulations Part 137 aerial application flight, for which a flight plan was not filed. The local flight was originating at the time of the accident.

According to the pilot, he was departing from runway 16 for a field where he was to apply 700 gallons of herbicide to cotton. The airplane had accelerated to 45 mph when he heard a "loud snap," and the right rudder pedal "fell to the floor". The airplane veered to the left, exited the runway, and ground-looped. The airplane came to rest upright on a northerly heading, in a grassy area. The pilot added that the winds were light and variable from the southwest, at the time of the accident.

The FAA inspector, who examined the airplane, reported that the right rudder control cable was separated at the aft fairlead. The airplane underwent its most recent annual inspection on March 20, 1999. The rudder cable had accumulated a total of 501 hours at the time of the accident. The inspector reported that the left wing's front and rear spars were structurally damaged.

The rudder control cable was examined at the NTSB Materials Laboratory in Washington, D.C. The cable separation was identified to be 2 feet 7.8 inches from the rudder horn (near the area of the aft fairlead). The separated ends of the cable were examined with an optical binocular microscope and a scanning electron microscope. The individual wires had a flat and shiny appearance, indicative of wear. The wear was primarily on one side of the cable, extending around 90 degrees of the cable circumference.

On August 27, 1999, Air Tractor Inc., of Olney, Texas, issued a service information letter (#802-63) regarding rudder cable wear at the aft fairlead. It stated that Air Tractor was aware that the rudder cables of the AT-802 and AT-802A wear at the aft fairlead. The service letter advised operators that a new cable, which incorporated a stainless steel sleeve that is crimped to the cable in the area of the fairlead, was available. The operator stated that they were aware of the service letter, but had not replaced the rudder cables.