What does filiform corrosion often indicate about the conditions of exposure?

Filiform corrosion is a specific type of corrosion that typically occurs in aluminum and is characterized by thread-like filaments that develop beneath a coating or paint. This type of corrosion often indicates that the metal has been exposed to conditions of high temperature and humidity, which facilitate the movement of moisture and promote the corrosion process.

In high humidity environments, moisture can accumulate and remain trapped underneath protective coatings. When combined with elevated temperatures, this creates an ideal setting for filiform corrosion to develop, as the moisture coupled with the right conditions lead to the breakdown of the protective layer and corrosion underneath it.

Understanding this phenomenon helps aircraft maintenance personnel to identify problem areas that could be related to environmental factors, which is crucial for preventing corrosion damage and ensuring the longevity of aircraft components.