Aviation Institute Of Maintenance (AIM) Block 1 Practice Test

Corrosion on aluminum airframes shows up as surface changes and material loss caused by chemical or electrochemical attack. The typical signs are pitting, which are small pits where the metal has been eaten away; discoloration, which comes from oxide or other corrosion products changing the metal’s color; and coating failure, where the protective paint or primer breaks down and lets corrosion proceed underneath. Warpage of the skin isn’t a typical corrosion sign because distortion or bending of the skin points to structural deformation from other causes, such as mechanical damage, improper manufacturing processes, or thermal/loads effects. While corrosion can eventually weaken a structure, its common visual indicators aren’t warped skin; they’re pits, color changes, and coating problems.