Incident Overview
Following an uneventful landing, while taxiing, the captain noticed that a section of the left wing was bent upward. Post-flight examination of the airplane identified the cause as a structural failure in the left wing.
Examination Findings
Inspection of the left wing revealed that rib No. 19 had failed chordwise at the midpoint between a row of rivets and nutplates on the lower attach angle. The failure was attributed to exfoliation corrosion, a form of corrosion that leads to material delamination and loss of structural integrity.
Inspection Requirements
The Federal Aviation Administration (FAA) approved 50-hour inspection for the aircraft type mandates a visual inspection of the attach angle and bolts. However, the inspection does not require removal of the wing tip to access the area, potentially limiting the visibility of corrosion in such locations.