Accident Details
On June 4, 2013, at approximately 0930 Pacific daylight time, a Piper PA-28-140, registration N5808U, experienced a loss of directional control during the landing roll at Skagit Regional Airport in Burlington, Washington. The aircraft was substantially damaged when it struck an airport sign and a ditch following the runway excursion. The private pilot, who was the sole occupant and owner of the aircraft, was not injured.
The flight was operated under Part 91 of the Federal Aviation Regulations as a personal cross-country flight. It had originated from Friday Harbor, Washington, about 20 minutes before the accident. Visual meteorological conditions were present, and no flight plan had been filed.
Pilot Account
According to the pilot, during the landing roll he applied left rudder to straighten the airplane but received no response. He then attempted to correct the aircraft's right-turning tendency with left braking, which was also ineffective. The airplane subsequently departed the right side of the runway and impacted an airport sign and a ditch, resulting in damage to the right wing.
Post-accident Examination
Examination of the aircraft after the accident revealed that the left rudder control bar had failed. The NTSB Materials Laboratory analyzed the rudder control bar and found a fatigue crack that originated from the edge of a weld. A rusted brown oxidized area was present near the middle of the crack, with surface topography and crack patterns consistent with slow fatigue growth that progressed from the exterior surface radially through the tube wall.
Background
The Piper PA-28-140, manufactured in 1970, had accumulated a total airframe time of 3,479 hours at the time of the accident. The most recent annual inspection was completed on May 25, 2013. A review of the aircraft's periodic inspection checklist, maintenance manual, and Piper Service Letter No. 671 (dated October 5, 1973) indicated that the rudder bar assembly should be inspected every 100 hours for cracks in the area where the failure occurred. The service letter also stated that the inspections could be discontinued if two reinforcement doublers were fabricated and welded to the rudder bar in the affected area. The accident aircraft's rudder bar did not have these doublers.