18 Questions
What does the presence of chipped or cracked paint around rivet heads indicate?
Loose or shifted rivets
How can you identify loose or tipped rivets during inspection?
They show up in groups and are tipped in the same direction
What might have caused a rivet to fail in shear if the shank appears joggled and the holes in the sheet are misaligned?
Excessive stress on the rivet
What does drilling off the head of a rivet help to determine during inspection?
The type of repair required
In what situation should rivet holes be carefully punched out after drilling off the head during inspection?
When there is no visible distortion
What corrective action should be taken if a rivet has failed in shear during inspection?
Determining what caused the stress and taking appropriate action
What is a challenge when substituting a material that is stronger but thinner for the original material?
The greater tensile strength of one material may be offset by less compressive strength in the other material.
Why should heat-treated aluminum alloys be handled with caution when forming?
They are prone to cracking when bent due to their brittleness.
Why are soft alloys not considered suitable for primary structures?
They lack the necessary strength.
How can strong aluminum alloys be formed effectively?
By annealing them before assembly to enhance their strength.
What method can be used to determine the size of rivets for a repair?
Refer to the size of the original rivets used by the manufacturer nearby.
If the skin thickness is 0.040-inch, what size of rivet should be used according to the rule mentioned in the text?
1/8-inch
What is the acceptable depth of a crack on a rivet head?
1⁄8 of the shank diameter
Where is corrosion most likely to occur on the inside of an aircraft?
Pockets and corners
What is the main cause of corrosion on an aircraft?
Chemical or electrochemical reaction with the environment
When preparing a damaged area for repair, what should be done with square corners?
Round all square corners
Why is it common practice in the industry to assume that some rivets are not effective in a pattern?
To avoid overloading adjacent rivets
What condition should cracks on a rivet head be confined to?
An area within a circle having a maximum diameter of 11⁄4 times the shank diameter
Study Notes
Rivet Inspection and Repair
- Chipped or cracked paint around rivet heads indicates the presence of fatigue or stress concentration.
- Loose or tipped rivets can be identified during inspection by visually checking for uneven rivet heads, dimpling, or bulging of the skin.
Rivet Failure
- A rivet that has failed in shear, with a joggled shank and misaligned holes in the sheet, may have been caused by improper installation or alignment during manufacturing.
- Drilling off the head of a rivet helps determine if the rivet has failed in shear or tension during inspection.
Rivet Removal and Replacement
- Rivet holes should be carefully punched out after drilling off the head during inspection to prevent damaging the surrounding material.
- If a rivet has failed in shear during inspection, it should be removed and replaced with a new one.
Material Substitution and Forming
- Substituting a stronger but thinner material for the original material can be challenging due to differences in formability and strength.
- Heat-treated aluminum alloys should be handled with caution when forming to avoid cracking or damaging the material.
- Soft alloys are not suitable for primary structures due to their low strength-to-weight ratio.
- Strong aluminum alloys can be formed effectively using specialized tools and techniques.
Rivet Sizing and Crack Acceptance
- The size of rivets for a repair can be determined by measuring the skin thickness and using the rivet size chart.
- For a 0.040-inch skin thickness, a 4.0 mm rivet should be used according to the rule.
- The acceptable depth of a crack on a rivet head is 0.010 inch or less.
Corrosion and Damage Repair
- Corrosion is most likely to occur on the inside of an aircraft in areas with high humidity and moisture.
- The main cause of corrosion on an aircraft is the presence of oxygen, moisture, and contaminants.
- When preparing a damaged area for repair, square corners should be rounded to prevent stress concentrations.
- It is common practice in the industry to assume that some rivets are not effective in a pattern to account for manufacturing defects or damage.
- Cracks on a rivet head should be confined to the top surface and not extend to the edges.
Learn about the inspection process of both shop and manufactured heads, surrounding skin, and structural parts of aircraft riveted joints. Understand how adjacent parts and paint condition can indicate the presence of shifted or loose rivets during repair.
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