Event Description
During the landing roll, the left main gear swivel link pin failed. This failure allowed the rear set of tires to become detached from the main strut and drag along the runway.
Metallurgical Findings
A metallurgical study of the failed swivel pin revealed several characteristics. Intergranular cracking was present through 40% of the pin's cross-section. Evidence of stress corrosion was found, attributed to overtorquing the nut on the threaded end of the pin. Traces of copper were detected within the crack; copper is sometimes used before chromium plating during overhaul. No overload evidence was observed in the preexistent crack, but indications showed that the final fracture was due to overload.
Maintenance History
The left main gear bogie was last overhauled in 1981. At the time of failure, it had accumulated 4,459 hours since that overhaul.