AAC Corrosion Prevention and Control 2 — Questions and Answers
Question 1: What is the primary purpose of a corrosion inhibiting compound (CIC) applied to Army aircraft?
- To increase the structural strength of metal components
- To provide a protective barrier that displaces moisture and inhibits the corrosion process (Correct answer)
- To improve aerodynamic performance by smoothing aircraft surfaces
- To identify corroded areas with a color change for inspection purposes
Correct answer: To provide a protective barrier that displaces moisture and inhibits the corrosion process
A corrosion inhibiting compound provides a protective barrier that displaces moisture from metal surfaces and contains chemical inhibitors that prevent the electrochemical corrosion process from occurring.
Question 2: What is intergranular corrosion and why is it particularly dangerous for aircraft structural integrity?
- Corrosion that occurs on the outer painted surface of metal components
- Corrosion that attacks the grain boundaries within a metal, weakening its structure from within without obvious external signs (Correct answer)
- Corrosion caused by direct contact between different metal alloys
- Corrosion that develops only in high-temperature turbine engine areas
Correct answer: Corrosion that attacks the grain boundaries within a metal, weakening its structure from within without obvious external signs
Intergranular corrosion attacks the grain boundaries within the metal structure, weakening the material from within without obvious external signs, making it extremely dangerous for structural integrity.
Question 3: How frequently should Army aircraft be washed to control corrosion accumulation under standard maintenance requirements?
- Once per year during the annual depot inspection
- At least every 30 days, or more frequently based on environmental exposure (Correct answer)
- Only when corrosion is visually detected during preflight inspection
- Every 180 days during phased maintenance cycles
Correct answer: At least every 30 days, or more frequently based on environmental exposure
Army aircraft must be washed at least every 30 days, or more frequently when operating in corrosive environments such as coastal or desert areas, to remove salt and contaminants that accelerate corrosion.
Question 4: Which corrosion severity level indicates that damage exceeds allowable limits and requires depot-level repair or component replacement?
- Level 1
- Level 2
- Level 3 (Correct answer)
- Level 4
Correct answer: Level 3
Level 3 corrosion indicates that the damage exceeds the allowable limits specified in the applicable technical manual, requiring depot-level repair or replacement of the affected component.
Question 5: What is the proper technique for removing light surface corrosion from an aluminum aircraft component?
- Using a steel wire brush and chemical paint stripper
- Using fine abrasive materials and hand tools, working in the direction of the metal grain (Correct answer)
- Applying high-pressure water blasting directed at the affected area
- Sandblasting the entire component surface to bare metal
Correct answer: Using fine abrasive materials and hand tools, working in the direction of the metal grain
Light surface corrosion on aluminum should be removed using fine abrasive materials and hand tools, working in the direction of the metal grain to minimize base metal removal and prevent additional surface damage.
Question 6: What is the purpose of anodizing aluminum aircraft components in Army aviation?
- To increase the weight-bearing strength and hardness of aluminum structural parts
- To create a hard, corrosion-resistant aluminum oxide layer on the component surface (Correct answer)
- To improve electrical conductivity for bonding and grounding purposes
- To prepare aluminum surfaces for welding repair procedures
Correct answer: To create a hard, corrosion-resistant aluminum oxide layer on the component surface
Anodizing creates a controlled, hard aluminum oxide layer on the component surface that is highly resistant to corrosion and provides an excellent base for subsequent paint adhesion.
Question 7: Which metal combination creates the greatest risk of galvanic corrosion when used together in Army aircraft construction?
- Aluminum in contact with titanium fasteners
- Steel fasteners in contact with aluminum skin panels
- Stainless steel fittings in contact with titanium tubing
- Copper components in contact with magnesium alloy parts (Correct answer)
Correct answer: Copper components in contact with magnesium alloy parts
Copper and magnesium are far apart on the galvanic series, making them the most susceptible combination, with magnesium acting as the anode and corroding rapidly whenever an electrolyte is present.
AAC Corrosion Prevention and Control 2
What is the primary purpose of a corrosion inhibiting compound (CIC) applied to Army aircraft?