Auburn, AL, USA
N125AR
Cessna 208B
According to the flight crew, during the takeoff roll the co-pilot noticed that the right rudder and trim controls were not responding. During the flight they began to diagnose the problem. The pilot continued the flight and made an uneventfully landing. During the post-landing examination of the airplane, the right rudder cable was found broken. Examination of the rudder cable by the NTSB Materials Laboratory found that the wire rope portion of the cable was fractured just inside the clevis fitting at the forward end of the cable. The fracture of the wire rope portion on the control cable assembly was the result of fatigue cracking that initiated because of the introduction of bending loads due to the over-torque of the clevis bolt during the manufacturing process.
On February 3, 2004, at 1400 central standard time, a Cessna 208B, N125AR, registered to and operated by Rushton Air, lost right rudder control shortly after takeoff from the Columbus Metro Airport in Columbus, Georgia. The repositioning flight was operated under the provisions of Title 14 CFR Part 91, and visual flight rules. Visual meteorological conditions prevailed and no flight plan was filed. The pilot and co-pilot were not injured, and the airplane was not damaged. The flight departed the Columbus Metro Airport, in Columbus, Georgia on February 3, 2004 at 1340, enroute to Auburn-Opelika Airport in Auburn, Alabama. According to the flight crew, during the takeoff roll the co-pilot noticed that the right rudder was not responding. Due to the high traffic volume at Columbus, Georgia they elected to proceed to the Auburn-Opelika Airport in Auburn, Alabama. During the flight they began to diagnose the problem. They found that the rudder trim was not responding and full deflection of the right rudder pedal did not have any effect. Further examination found the right rudder cable broken. The crew contacted their Chief Pilot and Director of Maintenance, and found out that there was nothing that could be done in-flight. The pilot asked that emergency vehicles meet them on runway 36 just as a precaution. The pilot did not declare an emergency. The airplane landed uneventfully on runway 36 and the pilot performed a normal shutdown. Examination of the rudder cable found it separated at the trailing end of its attaching clevis. The cable and clevice were sent to the NTSB Materials Laboratory in Washington, DC for further examination. Examination of the rudder cable by the NTSB Materials Laboratory found that the wire rope portion of the cable was fractured just inside the clevis fitting at the forward end of the cable. The strands of the wire rope had separated from each other over a distance of more than 1 foot from the cable end. The individual wires in most of the strands had not separated from each other or were separated over a much shorter distance. Visual examination of the fractured wire ends with the aid of a bench binocular microscope revealed that the wire fractures were aligned with each other within about 0.02 inch, and were located about 0.05 inch inside the end of the clevis fitting. Nearly all of the fractures were on a flat transverse plane, with no apparent necking down deformation, features typical of fatigue cracking. A few of the wires were fractured on a slant plane and did contain necking down deformation, features typical of overstress fracture; and a few of the wires had fractures with a mixture of fatigue and overstress features. Further examination of the clevis fitting revealed that the forward ends of the clevis tines were pinched together. The spacing between the tines was measured with calipers and found to be 0.18 inch near where the tines joined together and 0.13 inch near the tip. Visual examination of the inside surfaces of the tines of the clevis fitting revealed the presence of a dark rust-colored discoloration, typical of fretting or rubbing damage, adjacent to the tip of the tines. The exterior surface of the clevis fitting also contained imprint or rubbing marks from contact with the underside of the attachment bolt head and from the washer under the nut. On both sides of the clevis, the damage was found dominantly on the forward and aft of the attachment bolt hole (and much less on the upper and lower sides of the hole). The damage on this side was much more severe than on the other side. According to Cessna Aircraft Company, as a result of this failure, Cessna is adding a spacer to the production process that will be placed between the rudder cable clevis and the rod end. This change will also be reflected in the Cessna Illustrated Parts Catalog.
The fatigue fracture of the wire rope portion on the rudder control cable assembly due to improper installation and inadequate procedures by the aircraft manufacturer.
Source: NTSB Aviation Accident Database
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