What is a common indicator of material fatigue in aircraft structures?

The development of cracks or deformities in high-stress areas is a well-established indicator of material fatigue in aircraft structures. Fatigue occurs when a material is subjected to repeated loading and unloading cycles, which can lead to the initiation of micro-cracks that eventually grow over time. These cracks often appear in areas where stress concentrations are highest, such as joints, welds, and other structural points that bear significant loads.

Monitoring for cracks and deformations is crucial in aviation maintenance since these alterations can compromise the structural integrity and safety of the aircraft. Efficient inspections and timely repairs of these high-stress areas can help maintain aircraft viability and prevent catastrophic failures that could result from undetected fatigue.

In contrast, the increase in the aircraft's weight, smoothness of the exterior surfaces, and color changes in surface coatings do not directly indicate material fatigue. While changes in weight may reflect added components or fluids, they are not direct indicators of fatigue damage. Similarly, the exterior surface characteristics and coating colors may indicate other issues, such as corrosion or environmental wear, rather than the internal stresses and resultant fatigue experienced by the material itself.