Cleaning And Corrosion Control

Question 1

A primary reason why ordinary or otherwise non-approved cleaning compounds should not be used when washing aircraft is because their use can result in:
A. Hydrogen embrittlement in metal structures.
B. Hydrogen embrittlement in nonmetallic materials.
C. A general inability to remove compound residues.

Answer 1

A. Hydrogen embrittlement in metal structures.

Question 2

How many magnesium engine parts be cleaned?
A. Soak in a 20 percent caustic soda solution.
B. Spray with methyl ethyl ketone (MEK).
C. Wash with a commercial solvent, decarbonize, and scrape or grit blast.

Answer 2

C. Wash with a commercial solvent, decarbonize, and scrape or grit blast.

Question 3

When an anodized surface coating is damaged in service, it can be partially restored by:
A. Applying a thin coat of zinc chromate primer.
B. Chemical of surface treatment.
C. Use of suitable mild cleaner.

Answer 3

B. Chemical of surface treatment.

Question 4

For which of the following reasons would a water break test be conducted:
A. To make certain that a newly anodized aluminum surface is sufficiently coated.
B. To make certain that a bare metal surface is throughly clean.
C. To make certain that an anodizing coating has been sufficiently removed before an electrical bonding connection can be made.

Answer 4

B. To make certain that a bare metal surface is throughly clean.

Question 5

Select the solvent recommended for wipe down of cleaned surfaces just before painting.
A. Aliphatic naphtha.
B. Dry-cleaning solvent.
C. Aromatic naphtha.

Answer 5

A. Aliphatic naphtha.

Question 6

Nickel-cadmium battery cases and drain surfaces which have been affected by electrolyte should be neutralized with a solution of:
A. Boric acid.
B. Sodium bicarbonate.
C. Potassium hydroxide.

Answer 6

A. Boric acid.

Question 7

Which of the following are acceptable to use when utilizing chemical cleaning agents on aircraft?
A. Cotten fiber wiping cloths when using a flammable agent and atomizing spray equipment.
B. Microfiber wiping cloths when using a flammable agent and atomizing spray equipment.
C. Synthetic fiber wiping cloths when using a flammable agent.

Answer 7

A. Cotten fiber wiping cloths when using a flammable agent and atomizing spray equipment.

Question 8

Select the solvent used to clean acrylics and rubber.
A. Aliphatic naphtha.
B. Methyl ethyl ketone.
C. Aromatic naphtha.

Answer 8

A. Aliphatic naphtha.

Question 9

Fayed surfaces cause concern in chemical cleaning because of the danger of:
A. Forming passive oxides.
B. Entrapping corrosive materials.
C. Corrosion by imbedded iron oxide.

Answer 9

B. Entrapping corrosive materials.

Question 10

Caustic cleaning projects used on aluminum structures have the effect of producing:
A. Passive oxidation.
B. Improved corrosion resistance.
C. Corrosion.

Answer 10

C. Corrosion.

Question 11

Fretting corrosion is most likely to occur:
A. When two surface fit tightly together but can move relative to one another.
B. Only when two dissimilar metals are in contact.
C. When two surfaces fit loosely together and can move relative.

Answer 11

A. When two surface fit tightly together but can move relative to one another.

Question 12

The rust or corrosion that occurs with most metals is the result of:
A. A tendency for them to return to their natural state.
B. Blocking the flow of electrons in homogenous metals, or between dissimilar metals.
C. Electron flow in between metal for cathodic to anodic areas.

Answer 12

A. A tendency for them to return to their natural state.

Question 13

Which of the following are the desired effects of using alodine on aluminum alloy?
A. A smooth painting surface and increased corrosion resistance.
B. Relieved surface stresses.
C. A slightly rough surface and increased corrosion resistance.

Answer 13

C. A slightly rough surface and increased corrosion resistance.

Question 14

Which of the listed conditions is NOT one of the requirements for corrosion to occur?
A. The presence of an electrolyte.
B. Electrical contact between an anodic area and a cathodic area.
C. The presence of a passive oxide film.

Answer 14

C. The presence of a passive oxide film.

Question 15

The lifting or flaking of the metal at the surface due to delamination of the grain boundaries caused by the pressure of corrosion residual product buildup is called:
A. Brinelling.
B. Granulation.
C. Exfoliation.

Answer 15

C. Exfoliation.

Question 16

A nonelectrolytic chemical treatment for aluminum alloys to increase corrosion resistance and paint-bonding qualities is called:
A. Anodizing.
B. Alodizing.
C. Dichromating.

Answer 16

B. Alodizing.

Question 17

Which of the following are acceptable to use in cleaning anodized surfaces?
A. Steel wool, aluminum wool, and fiber bristle brushes.
B. Brass wire brushes and stainless steel wire brushes.
C. Aluminum wool and fiber bristle brushes.

Answer 17

C. Aluminum wool and fiber bristle brushes.

Question 18

Intergranular corrosion in aluminum alloy parts:
A. May be detected by surface pitting, and white, powdery formed on the surface of the metal.
B. Commonly appears as threadlike filaments of corrosion products under a dense film of paint.
C. Cannot always be detected by surface indications.

Answer 18

C. Cannot always be detected by surface indications.

Question 19

Which of the following may not be detectable even by carful visual inspection of the surface of aluminum alloys parts or structures?
A. Filiform corrosion.
B. Intergranular corrosion.
C. Uniform etch corrosion.

Answer 19

B. Intergranular corrosion.

Question 20

What may be used to remove corrosion from highly stressed steel surfaces?
A. Steel wire brushes.
B. Fine-grit aluminum oxide.
C. Medium-grit carborundum paper.

Answer 20

B. Fine-grit aluminum oxide.

Question 21

A primary cause of Intergranular corrosion is:
A. Improper heat treatment.
B. Dissimilar metal contact.
C. Improper application of primer.

Answer 21

A. Improper heat treatment.

Question 22

Corrosion should be removed from magnesium parts with a:
A. Stiff, nonmetallic brush.
B. Silicon carbide brush.
C. Carborundum abrasive.

Answer 22

A. Stiff, nonmetallic brush.

Question 23

Why is it important not to rotate the crankshaft after the corrosion preventive mixture has been put into the cylinders on engines prepared for storage?
A. Fuel may be drawn into one or more cylinders and dilute or wash off the corrosion preventive mixture.
B. The seal of corrosion preventive mixture will be broken.
C. Engine damage can occur from hydraulic lock.

Answer 23

B. The seal of corrosion preventive mixture will be broken.

Question 24

Which of the following is an acceptable first step procedure to help prevent scratching when cleaning a transparent plastic surface?
A. Gently wipe the surface with a clean, dry, soft cloth.
B. Flush the surface with clean water.
C. Gently wipe the surface with a clean, soft cloth moistened with de-mineralized or distilled water.

Answer 24

B. Flush the surface with clean water.

Question 25

What should be done to prevent rapid deterioration when oil or grease come in contact with a tire?
A. Wipe the trie thoroughly with a dry cloth, and then rinse with clean water.
B. Wipe the tire with a dry cloth followed by a washdown and rinse with soap and water.
C. Wipe the tire with a cloth dampened with aromatic naphtha and then wipe dry with a clean cloth.

Answer 25

B. Wipe the tire with a dry cloth followed by a washdown and rinse with soap and water.

Question 26

Galvanic corrosion is likely to be most rapid and severe when:
A. The surface area of the cathodic metal is smaller than surface area of the anodic metal.
B. The surface areas of the anodic and cathodic metals are approximately the same.
C. The surface area of the anodic metal is smaller than the surface area of the cathodic metal.

Answer 26

C. The surface area of the anodic metal is smaller than the surface area of the cathodic metal.

Question 27

Corrosion caused by galvanic action is the result of:
A. Excessive anodization.
B. Contact between two unlike metals.
C. Excessive etching.

Answer 27

B. Contact between two unlike metals.

Question 28

Which of these materials is the most anodic?
A. Cadmium.
B. 7075-T6 aluminum alloy.
C. Magnesium.

Answer 28

C. Magnesium.

Question 29

The interior surface of sealed structural steel tubing would be best protected against corrosion by which of the following?
A. Charging the tubing with dry nitrogen prior to sealing.
B. Evacuating moisture from the tubing before sealing.
C. A coating of linseed oil.

Answer 29

C. A coating of linseed oil.

Question 30

Which of these materials is the most cathodic?
A. Zinc.
B. 2024 aluminum alloy.
C. Stainless steel.

Answer 30

C. Stainless steel.

Question 31

Of the following, when and/or where is galvanic corrosion is most likely to occur?
A. When an electrolyte (water) cover the surface of an aluminum skin, seeps into the cracks between lap joints, and oxygen is excluded from the area.
B. At the interface of a steel fastener and aluminum alloy inspection plate in the presence of an electrolyte.
C. In an area of unprotected metal exposed to an atmosphere containing battery fumes, exhaust gases, or industrial contaminants.

Answer 31

B. At the interface of a steel fastener and aluminum alloy inspection plate in the presence of an electrolyte.

Question 32

One way of obtaining increased resistance to stress corrosion cracking is by:
A. Reliving compressive stresses (via heat treatment) on the metal surface.
B. Creating compressive stresses (via shot peening) on the metal surface.
C. Producing non uniform deformation while cold working during the manufacturing process.

Answer 32

B. Creating compressive stresses (via shot peening) on the metal surface.

Question 33

(1) In the corrosion process, it is the cathodic area or dissimilar cathodic material that corrodes.
(2) in the Galvanic or Electro-chemical series for metals, the most anodic metals are those that will give up electrons most easily.
Regarding the above statements,
A. Only 1 is true.
B. Only 2 is true.
C. Both 1 and 2 are true.

Answer 33

B. Only 2 is true.

Question 34

Spilled mercury on aluminum:
A. Greatly increase susceptibility to hydrogen embrittlement.
B. May cause impaired corrosion resistance if left in prolonged contact .
C. Causes rapid and severe corrosion that is very difficult to control.

Answer 34

C. Causes rapid and severe corrosion that is very difficult to control.