Incident Description
While stopped on the runway awaiting takeoff clearance, an aircraft experienced a collapse of the left main landing gear bogie. The incident occurred without any prior indication of structural failure.
Examination Findings
Postincident examination indicated that the aft bogie swivel joint lugs had failed due to stress corrosion cracking. The swivel joint did not have proper lubrication, which normally keeps water out. The lack of lubrication allowed the formation of corrosion on the surface of the lugs, and subsequent crack initiation at the corrosion pits.
Maintenance and Inspection Requirements
Operator maintenance requirements specified that the swivel joint be lubricated every weekend check and every 'A' check. The work cards for these two inspections called out in narrative form the lubricating of the bogie pivot joint. The cards called for the swivel joint to be lubricated by reference to a number on an illustration.
Historical Notices
The failure of the swivel joint lugs was the subject of Douglas Aircraft All Operator Letters in 1976 and 1990. These letters stressed to operators the importance of lubricating the swivel joint to prevent corrosion formation.