corrosion

A primary reason why ordinary or otherwise nonapproved cleaning compounds should not be used when washing aircraft is because their use can result in

hydrogen embrittlement in metal structures.

How may magnesium engine parts be cleaned

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

When an anodized surface coating is damaged in service, it can be partially restored by

chemical surface treatment.

For which of the following reasons would a water break test be conducted?

To make certain that a bare metal surface is thoroughly clean

Select the solvent recommended for wipedown of cleaned surfaces just before painting.

Aliphatic naptha.

Nickel-cadmium battery cases and drain surfaces which have been affected by electrolyte should be neutralized with a solution of

boric acid.

Which of the following are acceptable to use when utilizing chemical cleaning agents on aircraft?

1. Synthetic fiber wiping cloths when using a flammable agent.

2. Cotton fiber wiping cloths when using a flammable agent.

3. Atomizing spray equipment.

2 and 3

Select the solvent used to clean acrylics and rubber

Aliphatic naphtha.

Fayed surfaces cause concern in chemical cleaning because of the danger of

entrapping corrosive materials

Caustic cleaning products used on aluminum structures have the effect of producing

Corrosion

Fretting corrosion is most likely to occur

when two surfaces fit tightly together but can move relative to one another.

The rust or corrosion that occurs with most metals is the result of

a tendency for them to return to their natural state.

Which of the following are the desired effects of using Alodine on aluminum alloy?

1. A slightly rough surface.

2. Relieved surface stresses.

3. A smooth painting surface.

4. Increased corrosion resistance.

1 and 4

Which of the listed conditions is NOT one of the requirements for corrosion to occur?

The presence of a passive oxide film

The lifting or flaking of the metal at the surface due to delamination of grain boundaries caused by the pressure of corrosion residual product buildup is called

exfoliation

A nonelectrolytic chemical treatment for aluminum alloys to increase corrosion resistance and paint-bonding qualities is called

alodizing

Which of the following are acceptable to use in cleaning anodized surfaces?

1. Steel wool.

2. Brass wire brush.

3. Aluminum wool.

4. Stainless steel wire brush.

5. Fiber bristle brush.

3 & 5

Intergranular corrosion in aluminum alloy parts

cannot always be detected by surface indications

Which of the following may not be detectable even by careful visual inspection of the surface of aluminum alloy parts or structures?

Intergranular corrosion.

What may be used to remove corrosion from highly stressed steel surfaces?

Fine-grit aluminum oxide.

A primary cause of intergranular corrosion is

improper heat treatment.

Corrosion should be removed from magnesium parts with a

stiff, nonmetallic brush

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?

The seal of corrosion preventive mixture will be broken

Which of the following is an acceptable first step procedure to help prevent scratching when cleaning a transparent plastic surface?

Flush the surface with clean water

What should be done to prevent rapid deterioration when oil or grease come in contact with a tire?

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

Galvanic corrosion is likely to be most rapid and severe when

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

Corrosion caused by galvanic action is the result of

contact between two unlike metals.

Which of these materials is the most anodic?

Magnesium

The interior surface of sealed structural steel tubing would be best protected against corrosion by which of the following?

A coating of linseed oil.

Which of these materials is the most cathodic?

Stainless steel.

Of the following, when and/or where is galvanic corrosion is most likely to occur?

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

One way of obtaining increased resistance to stress corrosion cracking is by

creating compressive stresses (via shot peening) on the metal surface

(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,

only No. 2 is true.

Spilled mercury on aluminum

causes rapid and severe corrosion that is very difficult to control