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the National Bureau of Standards using laboratory equipment. With respect to the fracture, the Bureau of Standards report stated that the fracture surface that remained on the yoke was well preserved and showed no evidence of fatigue; the deformation associated with the fracture indicated it was caused by overload. Examination of the surfaces which mated with the missing portion of tubing showed no evidence of fatigue but clear evidence of abrasive action. indicating the missing portion of tubing was ground away. It is noteworthy that a failure of this unit, had it occurred, would not permit complete autopilot control of the elevators. Nose-down control would be available, nose-up control would not. Manually, nose-up control would be available, nose-down control would not.
All other damage found to the other portions of the longitudinal control system was clearly the result of impact.
Examination of the elevators, their associated mechanisms, and attachments, showed the elevators overtravelled with great force in both the up and down throws. One direction occurred when the aircraft struck the runway and the other occurred when the fuselage crashed to the runway from the near-vertical impact attitude.
According to the maintenance records on aircraft N 5140B, the last time the link assembly-clevis attachment was disconnected during maintenance was March 4, 1959. At that time the attachment was disconnected to replace the bearings following a writeup that, "Elevator torque tube clevis excess loose through yoke." Following this work an inspection of the work was signed off by an Associated Airmotive inspector. Thereafter, during a No. 3 inspection on June 10, 1959, a No. 4 inspection on July 22, 1959, and a No. 2 inspection on September 1, 1959, all of which require inspection of the link assembly-clevis attachment for wear, proper assembly, and security, this inspection item was signed off as completed by an inspector of Associated Airmotive. Except on July 22, 1959, the inspections were signed off by the same inspector, Milton T. Parker.
On September 2, 1959, Mr. Parker signed the aircraft and engine maintenance log that the No. 2 inspection was completed. Within two hours of flying time the accident occurred.
Inspector Parker testified that he recalled his September 1959 inspection of N 5140B, including that portion pertaining to the link assembly-clevis attachment. He stated that he had personally removed the inspection plate which permitted access to the attachment because it had been improperly left in place when the aircraft was "opened up." Inspector Parker stated he inspected the bearing for wear and the attaching bolt for wear and security. He stated that he found the nut was tight and the cotter key in place. Inspector Parker concluded that his inspection was complete, the components of the attachment were in good condition, and the attachment was properly secured.
Analysis and Conclusions
Examination of the longitudinal control system of N 5140B revealed the link assembly was disconnected from the Clevis and all of the components
