ACACC

Question 1

is a type of corrosion that occurs evenly over the entire exposed surface of a metal.

Answer 1

Uniform surface corrosion

Question 2

Uniform surface corrosion is also known as

Answer 2

General corrosion

Question 3

Type of material loss where metal deteriorates at a consistent rate across the exposed surface.

Answer 3

Even material lost

Question 4

A trait of uniform corrosion that allows engineers to estimate material degradation over time.

Answer 4

Predictability

Question 5

Common visual indicators of uniform corrosion, especially on iron and steel.

Answer 5

Dulling, roughening, rust

Question 6

The two most common elements that cause rust formation in metals like iron and steel.

Answer 6

Oxygen and moisture

Question 7

Type of environment that dissolves metal surfaces evenly due to chemical properties.

Answer 7

Acidic or basic environments

Question 8

Environment with high salt concentration that enhances moisture conductivity and corrosion.

Answer 8

Saltwater or saline environment

Question 9

Atmospheric compound that forms acid when combined with moisture, contributing to corrosion.

Answer 9

Sulfur dioxide (SO₂)

Question 10

Environmental conditions that accelerate corrosion by increasing reaction rates.

Answer 10

High temperatures and humidity

Question 11

Missing protective element that leaves metal surfaces vulnerable to corrosion.

Answer 11

Lack of protective coatings

Question 12

Type of corrosion with small, deep holes in metal

Answer 12

Pitting corrosion

Question 13

Common cause of pitting corrosion involving damage to a surface barrier.

Answer 13

Oxide film break

Question 14

Structural factor within a metal that can lead to pitting corrosion.

Answer 14

Metal non-uniformity

Question 15

Reason pitting is dangerous despite minimal loss.

Answer 15

Structural failure

Question 16

Type of corrosion more likely in metals with poor passive film protection.

Answer 16

Pitting corrosion

Question 17

Alloying elements that improve stainless steel’s resistance to pitting.

Answer 17

Chromium, molybdenum, nitrogen

Question 18

Ion known for breaking down passive films and causing pitting.

Answer 18

Chloride ions

Question 19

Factor that increases the rate of pitting at elevated levels.

Answer 19

Temperature

Question 20

pH condition that destabilizes protective layers on metal surfaces.

Answer 20

Low pH

Question 21

Oxygen-related condition that initiates pitting due to uneven exposure.

Answer 21

Differential aeration

Question 22

Environmental condition where lack of fluid movement promotes pitting.

Answer 22

Stagnant conditions

Question 23

Surface imperfection that can serve as a starting point for pits.

Answer 23

Scratches or roughness

Question 24

Chemical agents that speed up cathodic reactions, enhancing pitting.

Answer 24

Oxidizing agents

Question 25

This type of pitting corrosion are particularly dangerous as they can lead to rapid perforation with minimal visible surface damage.

Answer 25

Narrow and Deep Pits

Question 26

This type of pitting corrosion while they remove more surface material, they might be less likely to cause immediate structural failure compared to deep pits.

Answer 26

Wide and Shallow Pits

Question 27

This type of pitting corrosion have an oval shape

Answer 27

Elliptical pits

Question 28

This type of pitting corrosion propagate along the grain boundaries of the metal in a vertical direction

Answer 28

Vertical Grain Attack

Question 29

This type of pitting corrosion initiates beneath the surface, often hidden by a layer of uncorroded metal.

Answer 29

Subsurface Pitting

Question 30

This type of pitting corrosion pits that grow laterally beneath a coating or deposit, leading to its detachment.

Answer 30

Undercutting Pitting

Question 31

This type of pitting corrosion spread along the grain boundaries in a horizontal direction.

Answer 31

Horizontal Grain Attack

Question 32

Type of localized corrosion occurring in tight gaps or joints.

Answer 32

Crevice corrosion

Question 33

Common structural feature where crevice corrosion occurs.

Answer 33

Narrow garage

Question 34

Materials between which crevice corrosion can form.

Answer 34

- Metal-to-metal - metal-to-nonmetal

Question 35

Condition inside the crevice that promotes corrosion.

Answer 35

Stagnant solution

Question 36

Type of chemical imbalance that drives crevice corrosion.

Answer 36

Concentration difference

Question 37

Causes of Crevice Corrosion

Answer 37

- Stagnant Conditions - Oxygen Depletion - Differential Aeration - Accumulation of Corrosive Ions - Crevice Geometry - Type of Crevice (Metal-to-metal and metal-to-nonmetal) - Surface Condition

Question 38

Localized corrosion that occurs along the boundaries between metal grains.

Answer 38

Intergranular corrosion

Question 39

Alternate terms for intergranular corrosion.

Answer 39

Intergranular attack/weld decay

Question 40

Structural feature in metals where intergranular corrosion occurs.

Answer 40

Grain boundaries

Question 41

Part of the metal that remains mostly unaffected during intergranular corrosion

Answer 41

Bulk of the grains

Question 42

Basic structural unit of crystalline metals.

Answer 42

Grain (crystallite)

Question 43

materials susceptible to Intergranular Corrosion

Answer 43

- authentic stainless steel - aluminum alloys - nickel-based alloys - copper-based alloys

Question 44

Detection of Intergranular Corrosion

Answer 44

- visual examination - electrochemical tests - non-destructive testing

Question 45

is a sneaky and dangerous form of corrosion that results in the unexpected and sudden cracking of a metal alloy subjected to both tensile stress and a corrosive environment.

Answer 45

STRESS CORROSION CRACKING (SCC)

Question 46

In stress corrosion cracking what happens to the metal at a microscopic level

Answer 46

pulls apart

Question 47

is an electrochemical process that occurs when two dissimilar metals are in electrical contact in the presence of an electrolyte (such as water containing salts or acids).

Answer 47

Galvanic Corrosion

Question 48

In galvanic corrosion which metal is being corroded

Answer 48

active (anodic)

Question 49

In galvanic corrosion which metal is being protected

Answer 49

noble (cathodic)

Question 50

(Less Noble/More Active): Metals higher up in the galvanic series have a more negative electrochemical potential. They tend to lose electrons (oxidize) and corrode more readily. They act as the anode in a galvanic couple.

Answer 50

Anodic Metals

Question 51

(More Noble/Less Active): Metals lower down in the galvanic series have a more positive electrochemical potential. They tend to accept electrons (reduce) and corrode less readily. They act as the cathode in a galvanic couple.

Answer 51

Cathodic Metals

Question 52

What materials should be used for cleaning

Answer 52

manufacturer-recommended or MIL-SPEC approved

Question 53

What is the risk in using commercial household cleaners

Answer 53

hydrogen embrittlement

Question 54

approved cleaners are cleaning products that meet the rigorous standards set by the U.S. military

Answer 54

MIL-SPEC

Question 55

Ratio for water-to-cleaner emulsion for general surface

Answer 55

1:5 / 1:3

Question 56

For heavily soiled areas what should be the ratio of cleaner mix

Answer 56

1:2

Question 57

For stubborn stains and targeted cleaning what should be the ratio of cleaner and what other chemical should be added

Answer 57

- 1:2 - varsol / kerosene

Question 58

What cleaner should be use for oil, grease, preservatives

Answer 58

- dry cleaning solvent - naptha

Question 59

This cleaner dissolves oil/grease, safe on rubber/acrylic

Answer 59

Aliphatic naphtha

Question 60

This cleaner damages rubber/acrylic

Answer 60

Aromatic naphtha

Question 61

For magnesium parts what should be done before painting

Answer 61

prep with dichromate solution

Question 62

Aluminum cleaning: * Use ___, easy-to-remove cleaners * For abrasives, only use ___ * Avoid ___ — risk of dissimilar corrosion

Answer 62

- neutral - aluminum wool or aluminum oxide sandpaper - steel wool, carborundum paper

Question 63

Aircraft components that uses magnesium

Answer 63

- thrust reversers - jet engine fan frames - transmission casings - wheels/seat frames

Question 64

Before Applying Cleaning Agents * Open all ___ * Use ___ (e.g., cotton) avoid synthetics * Do not ___ chemical agents, violates environmental rules * Keep away from ___ * Never ___ cleaning agents — creates fire/disposal hazards

Answer 64

- battery circuit breakers - natural-fiber cloths - atomize - flames, arcs, and electrical circuits - mix cleaning agents

Question 65

During and After Use * Follow ___, avoid over- concentration * Do not allow agents to dry on surfaces, leads to ___ * Open ___ to prevent water/chemical entrapment * Avoid over-applying cleaners on ___, removes internal lubricant

Answer 65

- manufacturer’s dilution recommendations - streaking and damage - drain holes and flap valves - control cables

Question 66

Hydrogen embrittlement is caused by

Answer 66

acidic/alkaline cleaners or plating solutions

Question 67

Hydrogen Embrittlement affects

Answer 67

- high-strength steels - aluminum - stainless steel

Question 68

After-Cleaning Procedures * Avoid spraying ___, and other electrical parts * After high-pressure washing of: * Wheel wells, flap tracks, hinges ___ these areas * Prevents water entrapment and corrosion

Answer 68

- magnetos, wiring harnesses - re-lubricate

Question 69

Best practices for exterior finish maintenance

Answer 69

- regular cleaning and waxing - clear all drain holes - removal of exhaust deposits

Question 70

Plastic & Plexiglass Surfaces - Never ___ dusty surfaces, causes scratches and static buildup

Answer 70

dry-wipe

Question 71

For tires what should be used to clean it

Answer 71

soap and water

Question 72

Rubber deice boots contain this type of coating and should not be scrub harshly

Answer 72

conductive coatings

Question 73

For radomes and composites what cleaner should be use and what coating does it have

Answer 73

- non-abrasive cleaners - radio-transparent coatings

Question 74

Cleaning process for powerplants

Answer 74

- Check for oil leaks - Use soap or solvent - let it sit - scrub - rinse - wait it to dry before startup

Question 75

Post cleaning process for powerplants

Answer 75

- lubricate controls and rod ends - remove all protective coverings

Question 76

is the most basic and commonly used method for corrosion detection

Answer 76

Visual inspection

Question 77

A tool used for visual inspection to help in enlarging small surface features

Answer 77

Magnifying glasses

Question 78

A tool used for visual inspection to allow viewing of hidden or hard-to-reach areas

Answer 78

Inspection mirrors

Question 79

A tool used for visual inspection to provide internal views of closed structures through small openings or access ports

Answer 79

Borescopes and fiber optics

Question 80

This method involves applying a visible or fluorescent dye to the surface of a material. The dye seeps into surface-breaking cracks and is then drawn out with a developer, making flaws visible under appropriate lighting.

Answer 80

Dye Penetrant Inspection