What is the major type of damage to aluminum structures that is caused by exposure to the weather?
corrosion
Name several methods for forming sheet metal.
Bending or folding, stretching, shrinking, bumping, and crimping.
What are the dimensions fo a properly formed rivet head?
the head should be 1 1/2 times the shank diameter in width and 1/2 the shank diameter in height
Describe the markings found on the heads of A, B, D, AD, and DD rivets.
A rivets are plain, B rivets have a cross, D rivets have a raised dot, AD rivets have a dimple, and DD rivets have a double dash.
What happens to the stem of a self-plugging (friction lock) rivet when the rivet is installed?
The stem is pulled until it snaps off and the remaining projecting part is trimmed flush with the head.
Name at least three types of self-plugging mechanical lock rivets.
CherryMAX, CherryLOCK, OLYMPIC-LOK, and HuckLok.
What is the difference between the tools required to pull a CherryLock rivet and a CherryMax rivet?
CherryLock rivets require a tool for each different size and head shape, while one pulling tool woll set any size CherryMax rivet
Which of the five stresses is the most common cause of rivet failure?
shear
If a 2024 rivet must be replaced with a 2117 rivet, how do you determine the size to be used?
for 5/32" or smaller diameter, use the next larger size 2117 rivet, assuming that the edge distance and spacing meet the minimum requirements
Describe the process for determining the total length of a solid rivet for a particular installation.
add the grip length (thickness of the materials being joined) plus 1 1/2 times the rivet diameter.
What minimum edge distance and spacing should be used for a single row of protruding head rivets?
not less than two rivet diameters from the edge and not less than three rivet diameters apart
How can a mechanic determine whether the countersink for a flush rivet should be dimpled or drilled?
By the thickness of the top sheet; thin sheets are dimpled while thick sheets may be countersunk.
What action is taken to prevent cracks from forming while dimpling magnesium or some hard sheet metals?
Hot dimpling equipment is used to preheat and soften the metal before the dimple is formed.
What type of damage can occur when using a rivet set that does not properly fit the rivet?
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
Why is it important to use the proper size and weight bucking bar when performing sheet metal riveting?
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
What procedures should be followed to properly remove a solid-shank rivet?
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 m
What are the two special calculations that must be made when bending sheet metal?
Bend allowance and setback
What factors must be considered in order to determine setback?
The thickness of the metal and the bend radius.
What is done to a corner where two bends intersect to prevent cracking?
Relief holes are drilled in the corner.
What are the two reasons for installing a lightening hole in a sheet metal wing rib?
lightening holes reduce the weight and increase stiffness.
Describe a joggle and explain its function.
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.
When repairing an all-metal aircraft, how do you determine what metals should be used?
always use metal of the same type and thickness as the original structure.