Sheet Metal Oral (Odd #'s)

Question 1

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

Answer 1

Corrosion

Question 2

Name several (at least four) methods of forming sheet metal.

Answer 2

Bending, stretching, shrinking, bumping

Question 3

What are the dimensions of a properly formed rivet head?

Answer 3

The head should be 1.5D in width and .5D in height

Question 4

Describe the markings found on the heads of an “A” rivet

Answer 4

Plain

Question 5

Describe the markings found on the heads of an “B” rivet.

Answer 5

A cross

Question 6

Describe the markings found on the heads of an “D” rivet.

Answer 6

Raised dot

Question 7

Describe the markings found on the heads of an “AD” rivet.

Answer 7

Dimple

Question 8

Describe the markings found on the heads of an “DD” rivet.

Answer 8

A double dash

Question 9

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

Answer 9

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

Question 10

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

Answer 10

Cherry Max, Cherry Lock, Olympic LOK, and HukLok rivets

Question 11

What is the difference between the tools required to pull a Cherry-Lock rivet and a Cherry-MAX rivet?

Answer 11

Cherry Lock rivets require a tool for each different size and head shape, and Cherry Max requires one tool for any size set.

Question 12

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

Answer 12

Shear

Question 13

If a 2024 rivet must be replaced with a 2017 rivet, how do you determine the size to be used?

Answer 13

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 14

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

Answer 14

Add the grip length plus 1 times the rivet diameter.

Question 15

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

Answer 15

Not less than 2D for edge distance, and 3D for rivet spacing

Question 16

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

Answer 16

By the thickness of the top sheet. Thin sheets are dimpled while thick sheets may be countersunk.

Question 17

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

Answer 17

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

Question 18

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

Answer 18

If the radius of the set is too small, the rivet head may be damaged. Whereas a set with an oversized radius may cause damage to the sheet metal.

Question 19

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

Answer 19

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

Question 20

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

Answer 20

Center punch the rivet and then drill just to the base of the rivet head with the same size or one size smaller drill.

Question 21

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

Answer 21

Bend allowance and setback

Question 22

What factors must be considered in order to determine setback?

Answer 22

Thickness of the metal and bend radius

Question 23

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

Answer 23

Relief holes are drilled in the corners

Question 24

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

Answer 24

Reduce weight and increase stiffness

Question 25

Describe a joggle, and explain its function.

Answer 25

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 26

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

Answer 26

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