Sheet Metal Oral (Odd #'s) Flashcards
What is the major type of damage to aluminum structures that is caused by exposure to the weather?
Corrosion
Name several (at least four) methods of forming sheet metal.
Bending, stretching, shrinking, bumping
What are the dimensions of a properly formed rivet head?
The head should be 1.5D in width and .5D in height
Describe the markings found on the heads of an “A” rivet
Plain
Describe the markings found on the heads of an “B” rivet.
A cross
Describe the markings found on the heads of an “D” rivet.
Raised dot
Describe the markings found on the heads of an “AD” rivet.
Dimple
Describe the markings found on the heads of an “DD” rivet.
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.
Cherry Max, Cherry Lock, Olympic LOK, and HukLok rivets
What is the difference between the tools required to pull a Cherry-Lock rivet and a Cherry-MAX rivet?
Cherry Lock rivets require a tool for each different size and head shape, and Cherry Max requires one tool for any size set.
Which of the five stresses is the most common cause of rivet failure?
Shear
If a 2024 rivet must be replaced with a 2017 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 plus 1 times the rivet diameter.
What minimum edge distance and spacing should be used for a single row of protruding head rivets.
Not less than 2D for edge distance, and 3D for rivet spacing
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 other 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 oversized 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. If a bucking bar is too light, it 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.
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?
Thickness of the metal and bend radius
What is done to a corner where two bends intersect to prevent cracking?
Relief holes are drilled in the corners
What are the two reasons for installing a lightening hole in a sheet metal wing rib?
Reduce 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.
