Corrosion Control and Treatment Flashcards
7 cards from real AMT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Corrosion Control and Treatment flashcards as text
Stress corrosion cracking (SCC) in aircraft structures is caused by the combination of:
Answer: Tensile stress and a corrosive environment acting simultaneously
SCC requires the simultaneous presence of tensile stress (residual or applied) and a specific corrosive environment, causing cracks to propagate along grain boundaries.
Exfoliation corrosion is characterized by:
Answer: Laminar separation of metal layers parallel to the surface
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.
Which chemical is commonly used to neutralize alkaline cleaning residues on aluminum before corrosion treatment?
Answer: Dilute chromic acid or phosphoric acid wash
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.
What is the primary reason magnesium aircraft components require immediate and thorough corrosion treatment?
Answer: Magnesium corrodes extremely rapidly and can penetrate deeply in a short time
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.
Filiform corrosion appears as:
Answer: Thin worm-like threads running under intact paint or coatings
Filiform corrosion forms thread-like or worm-like tracks beneath paint or surface coatings, often appearing on aluminum and steel in humid environments.
When inspecting a suspected corrosion area on a steel aircraft component, the presence of reddish-brown deposits indicates:
Answer: Iron oxide (rust), confirming active or past corrosion of steel
Reddish-brown deposits on steel are iron oxide (rust), a product of steel corrosion that confirms corrosive attack has occurred and requires treatment.
After mechanical removal of corrosion from a structural aluminum part, the technician should:
Answer: Apply a conversion coating (such as alodine) followed by primer before painting
Following corrosion removal, the bare aluminum must be treated with a conversion coating and primed promptly to restore corrosion protection before topcoating.