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
Crevice corrosion is most likely to occur in which of the following locations?
Answer: Gaps, lap joints, and areas under fastener heads where moisture is trapped
Crevice corrosion initiates in tight spaces where moisture and oxygen are trapped, such as lap joints, under bolt heads, and in seams where differential aeration cells form.
Which factor most significantly accelerates galvanic corrosion in a dissimilar metal couple?
Answer: A large cathode-to-anode surface area ratio
A large cathodic area coupled with a small anodic area concentrates the corrosive attack on the anode, greatly accelerating its corrosion rate.
Which sealant application method is used to prevent moisture intrusion at fastener holes in a wet-wing fuel tank?
Answer: Faying surface sealing and fillet sealing around every fastener
Fuel-tank integrity requires both faying surface sealant between mating surfaces and fillet seals around fasteners to prevent fuel and moisture ingress.
What is the galvanic series used for in corrosion control?
Answer: To rank metals by their electrochemical activity and predict galvanic corrosion potential
The galvanic series ranks metals from most active (anodic) to most noble (cathodic), allowing technicians to predict which metal will corrode when two dissimilar metals are joined.
When treating corrosion on a titanium aircraft component, the technician should be aware that:
Answer: Titanium is highly corrosion-resistant but can suffer from stress corrosion cracking in specific environments
Titanium is highly corrosion-resistant due to its stable oxide layer but is susceptible to stress corrosion cracking when exposed to certain chemicals such as methanol or red fuming nitric acid.
The 'pillowing' appearance around rivets on an aluminum skin panel is indicative of:
Answer: Corrosion between the skin and underlying structure causing the skin to bulge
Pillowing around rivets occurs when corrosion between layers causes volumetric expansion of corrosion products, pushing the outer skin away from the substrate.
Which of the following best describes the function of a sacrificial anode?
Answer: A less noble metal intentionally coupled to a structure to corrode preferentially and protect the structure
A sacrificial anode is a highly active metal (such as zinc or magnesium) attached to a structure; it corrodes preferentially, protecting the more noble structural metal.