Airframe Flashcards
Fretting corrosion is most likely to occur
When two surfaces fit tightly together but can move relative to one another.
The core material of Alclad 2024-T4 is
heat treated aluminum alloy, and the surface material is commercially pure aluminum.
The rust or corrosion that occurs with most metals is the result of
Metal returning to its original content
Why is it considered good practice to normalize a part after welding?
To relieve internal stresses developed within the base metal.
Which of these materials is the most cathodic?
Stainless steel.
Which condition indicates a part has cooled too quickly after being welded?
Cracking adjacent to the weld.
Select the solvent used to clean acrylics and rubber.
Aliphatic naphtha.
Caustic cleaning products used on aluminum structures have the effect of producing
corrosion.
Which of the following occurs when a mechanical force is repeatedly applied to most metals at room temperature, such as rolling, hammering, or bending?
1. The metals become artificially aged.
2. The metals become stress corrosion cracked.
3. The metals become cold worked, strain or work hardened.
3.
Which of the listed conditions is NOT one of the requirements for corrosion to occur?
The presence of a passive oxide film.
What aluminum alloy designations indicate that the metal has received no hardening or tempering treatment?
3003-F.
A primary cause of intergranular corrosion is
improper heat treatment.
Which of the following are acceptable to use in cleaning anodized surfaces?
- Steel wool.
- Brass wire brush.
- Aluminum wool.
- Stainless steel wire brush.
- Fiber bristle brush.
3 & 5.
Galvanic corrosion at the interface of a dissimilar metal part may best be prevented by
placing a nonporous dielectric material between the surfaces.
The Society of Automotive Engineers (SAE) uses a numerical index system to identify the composition of various steels. In the number “4130” designating chromium molybdenum steel, the first digit indicates the
basic alloying element
What does the acronym T.S.O. mean regarding a type certificated aircraft part, material, component, and/or process?
Technical Standard Order.
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.
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.
The interior surface of sealed structural steel tubing would be best protected against corrosion by which of the following?
A coating of hot linseed oil.
(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
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
Which of the following are acceptable to use when utilizing chemical cleaning and/or depainting agents to clean aircraft?
- Synthetic fiber wiping cloths when using a flammable agent.
- Cotton fiber wiping cloths when using a flammable agent.
- Atomizing spray equipment.
2.
Which of the following describe the effects of annealing steel and aluminum alloys?
1. Decrease in internal stress.
2. Softening of the metal.
3. Improved corrosion resistance.
1, 2
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.
How may magnesium engine parts be cleaned?
Wash with a commercial solvent, decarbonize, and scrape or grit blast.
Which heat treating process of metal produces a hard, wear-resistant surface over a strong, tough core?
Case hardening.
What may be used to remove corrosion from highly stressed steel surfaces?
Fine-grit aluminum oxide.
Alclad is a metal consisting of
pure aluminum surface layers on an aluminum alloy core.
Spilled mercury on aluminum
causes rapid and severe corrosion that is very difficult to control.
What is descriptive of the annealing process of steel during and after it has been annealed?
Slow cooling; low strength.
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.
What type of corrosion attacks grain boundaries of aluminum alloys which are improperly or inadequately heat treated?
Intergranular.
In the four-digit aluminum index system number 2024, the first digit indicates
the major alloying element.
In examining and evaluating a welded joint, a mechanic should be familiar with
the parts, proportions, and formation of a weld.
When an anodized surface coating is damaged in service, it can be partially restored by
chemical surface treatment.
One characteristic of a good weld is that no oxide should be formed on the base metal at a distance from the weld of more than
1/2 inch.
Select the solvent recommended for wipedown of cleaned surfaces just before painting.
Aliphatic naphtha.
Why is steel tempered after being hardened?
To relieve its internal stresses and reduce its brittleness.
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.
Normalizing is a process of heat treating
iron-base metals only.
Which material cannot be heat treated repeatedly without harmful effects?
Clad aluminum alloy.
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.
Which heat treating operation would be performed when the surface of the metal is changed chemically by introducing a high carbide or nitride content?
Case hardening.
The aluminum code number 1100 identifies what type of aluminum?
99 percent commercially pure aluminum.
What is generally used in the construction of aircraft engine firewalls?
Stainless steel
A nonelectrolytic chemical treatment for aluminum alloys to increase corrosion resistance and paint-bonding qualities is called
alodizing.
Which of these materials is the most anodic
Magnesium.
Select a characteristic of a good gas weld.
The weld should taper off smoothly into the base metal.
Corrosion caused by galvanic action is the result of
contact between two unlike metals.
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.
