What condition typically signals that metal flaking may occur on coated surfaces?

The condition that typically signals that metal flaking may occur on coated surfaces is excessive loads. When components experience loads that exceed their designed limits, the stresses can cause fatigue or deformation in the coated surface as well as within the substrate material beneath the coating. This can lead to the failure of the adhesive bond between the coating and the substrate, resulting in metal flaking.

Excessive loads can happen due to multiple factors such as improper installation, operational overload, or even environmental factors that unexpectedly increase the load on the surfaces. Monitoring and managing the loads on components is crucial in maintenance to prevent damage that leads to flaking, which not only compromises the coating but can also lead to further structural issues if left unchecked.

While undetected corrosion, overheating, or exposure to a corrosive environment can also result in surface deterioration, the specific link between excessive loads and the failure or flaking of coatings stands out as a prominent factor in materials engineering and maintenance practices, especially in the context of aviation powerplants where material integrity is critical.