Sheet metal structures

Question 1

What is the major type of damage to aluminum structures that is caused by exposure to weather?

Answer 1

Corrosion

Question 2

Name several methods for forming sheet metal

Answer 2

Bending, folding, stretching, shrinking bumping and crimping

Question 3

What are the dimensions of a properly formed rivet head?

Answer 3

The head should be 1 and 1/2 times the shank diameter in width and 1/2 the shank diameter in height.

Question 4

Describe the markings found on the heads of A, B, D, AD and DD rivets

Answer 4

A rivet are plain
B rivets have a cross
D rivets have a raised dot
AD rivets have a dimple
DD rivets have a double dash

Question 5

What happens to the stem of a self-plugging (friction lock) rivet when the rivet is installed?

Answer 5

the stem is pulled until it snaps off and the remaining projecting part is trimmed flush with the head

Question 6

Name at least three types of self-plugging mechanical lock rivets.

Answer 6

CherryMAX,
CherryLOCK
OLYMPIC-LOK
HuckLok

Question 7

What is the difference between the tools required to pull a CherryLOCK rivet and a CherryMAX rivet?

Answer 7

CherryLOCK rivets require a tool for each different size and head shape, while one pulling tool will set any size CherryMAX rivet

Question 8

Which of the five stresses is the most common cause of rivet failure?

Answer 8

Shear

Question 9

If a 2024 rivet must be replaced with a 2117 rivet, how do you determine the size to be used?

Answer 9

For 5/32” or smaller diameter, use the next larger size 2117 rivet, assuming that the edge distance and spacing meet the minimum requirements.

Question 10

Describe the process for determining the total length of a solid rivet for a particular installation.

Answer 10

Add the grip length (thickness of the materials being join) plus 1/2 times the rivet diameter.

Question 11

What minimum edge distance and spacing should be used for a single row of protruding head rivets?

Answer 11

Not less than two rivet diameters from the edge and not less than three rivet diameters apart

Question 12

How can a mechanic determine whether the countersink for a flush rivet should be dimpled of drilled?

Answer 12

By the thickness of the top sheet; thin sheets are dimpled when thick sheets may be countersunk

Question 13

What action is taken to prevent cracks from forming while dimpling magnesium or some hard sheet metals?

Answer 13

Hot dimpling equipment is used to preheat and soften the metal before the dimple is formed.

Question 14

What type of damage can occur when using a rivet set that does not properly fit the rivet?

Answer 14

If the radius of the set is too small, the rivet head may be damaged, whereas a set with an over-sized radius may cause damage to the sheet metal

Question 15

Why is it important to use the proper size and weight bucking bar when performing sheet metal riveting?

Answer 15

If a bucking bar is too large or heavy it may be difficult to control and may cause damage to the surrounding structure, whereas a bucking bar that is too light will not properly upset the rivet before work hardening occurs.

Question 16

What procedures should be followed to properly remove a solid-shank rivet?

Answer 16

Center punch the rivet and then drill just to the base of the rivet head with the same size or one size smaller drill. Once drilled, use a pin punch to tip off the rivet head and drive the remaining shank out of the hole while supporting the surrounding metal.

Question 17

What are the two special calculations that must be made when bending sheet metal.

Answer 17

Bend allowance and setback

Question 18

What factors must be considered in order to determine setback?

Answer 18

The thickness of the metal and the bend radius

Question 19

What is done to a corner where two bends intersect to prevent cracking?

Answer 19

relief holes are drilled in the corner

Question 20

What are the two reasons for installing a lightening hole in a sheet metal wing rib?

Answer 20

reduce weight and increase stiffness

Question 21

Describe a joggle and explain its function

Answer 21

A joggle is an offset formed at an intersection of two or more sheets of metal to allow the multiple sheets to be stacked flat against each other.

Question 22

When repairing an all-metal aircraft, how do you determine what metals should be used?

Answer 22

Always use metal of the same type and thickness as the original structure.