Incident Description
The left main gear collapsed and partially separated from the aircraft structure. Examination of the gear assembly revealed a failure in the drag strut assembly, part number 65-57903-11.
Examination Findings
Evidence of a pre-existing crack was found prior to the strut separation. The crack was identified as stress corrosion cracking, which probably initiated from previous damage to the outer surface of the strut cylinder. That damage resulted from a tire blowout incident that occurred on March 10, 1982.
Further Analysis
The investigation indicated that either a small crack or a group of cracks initiated in the strut at the time of the prior damage, or the damage was severe enough to disrupt the integrity of the surface finish and produce a notch and/or unfavorable residual stress. This made the strut susceptible to stress corrosion cracking in that area.