What is the primary concern with a defect in a highly stressed metal component?

A defect in a highly stressed metal component raises significant concerns primarily due to stress concentrations. When a defect, such as a crack or a corrosion pit, exists in a component that is subjected to high stresses, it can serve as a stress riser. This means that the local stress in the vicinity of the defect can become significantly higher than the average stress in the portion of the material that is defect-free.

Stress concentrations are critical because they can lead to premature failure of the component. In high-stress situations, the presence of a defect can result in fatigue failure, where the material fails after repeated stress cycles, or catastrophic failure, where the component breaks suddenly and without warning. Understanding and addressing stress concentrations in structural repairs is essential for maintaining the safety and integrity of aircraft metal components.

Other concerns, such as weight considerations, environmental factors, and visual appearance, while relevant in the broader context of aircraft structure, do not directly impact the immediate structural integrity and safety as profoundly as stress concentrations do. Hence, the primary focus when assessing defects in highly stressed components must be on how those defects can alter the stress distribution and lead to failure.