Failure Analysis of Aircraft Aluminum Alloy Structures in Coastal Environments

The failure of aluminum alloy stringer on the tour airplane servicing in the coastal environment of the Fiji Islands were analyzed. Through the analysis of surface topographies and failure characteristics and the consideration of service environment, the evolvement of failure process and the failure mechanisms were analyzed. Findings showed that ultraviolet radiation, temperature, high-humidity and salt spray caused the aging failure of structure coating and then pitting corrosion occurred in the oxide film on aluminum alloy. With the ongoing corrosion along the grain boundary, intergranular corrosion appeared. When the intergranular corrosion continued developing to the adjacent layers, denudation occurred. The volume expansion effect of corrosion products caused the stress concentration on the tip of corroded area and resulted in the initiation of cracks.