AMT Corrosion Control and Treatment 3

Question 1

Stress corrosion cracking (SCC) in aircraft structures is caused by the combination of:

Accepted Answer

Tensile stress and a corrosive environment acting simultaneously

Answer

SCC requires the simultaneous presence of tensile stress (residual or applied) and a specific corrosive environment, causing cracks to propagate along grain boundaries.

Question 2

Exfoliation corrosion is characterized by:

Accepted Answer

Laminar separation of metal layers parallel to the surface

Answer

Exfoliation corrosion causes the metal to delaminate in layers parallel to the rolled surface, producing a flaking or leafing appearance typical in high-strength aluminum alloys.

Question 3

Which chemical is commonly used to neutralize alkaline cleaning residues on aluminum before corrosion treatment?

Accepted Answer

Dilute chromic acid or phosphoric acid wash

Answer

A dilute acid rinse (such as chromic acid or phosphoric acid-based wash) neutralizes alkaline cleaner residues and prepares the aluminum surface for subsequent treatment.

Question 4

What is the primary reason magnesium aircraft components require immediate and thorough corrosion treatment?

Accepted Answer

Magnesium corrodes extremely rapidly and can penetrate deeply in a short time

Answer

Magnesium is one of the most anodic (active) metals used in aircraft construction and corrodes very rapidly, requiring prompt treatment to prevent deep structural damage.

Question 5

Filiform corrosion appears as:

Accepted Answer

Thin worm-like threads running under intact paint or coatings

Answer

Filiform corrosion forms thread-like or worm-like tracks beneath paint or surface coatings, often appearing on aluminum and steel in humid environments.

(AMT) Aviation Maintenance Technician Practice Test

(AMT) Aviation Maintenance Technician Practice Test

AMT Corrosion Control and Treatment 3