Section II Airframe Structures (Sheet Metal and Non Metallics)

Question 1

What is the grip length of a rivet?

Answer 1

The combined thickness of the materials to be joined by a rivet.

Question 2

Where are special rivets such as Huck or Cherry lock rivets used?

Answer 2

They are used in places where access to both sides of the rivet is impossible, or where limited space will not permit the use of a bucking bar. These rivets require special tools, installation, and removal procedures. They are commonly called blind rivets.

Question 3

What is bonded honeycomb (sandwhich) construction?

Answer 3

A laminar construction consisting of a combination of alternating dissimilar materials, assembled and fixed

Question 4

Where are Sandwich construction assemblies used?

Answer 4

Areas such as bulkheads, control surfaces, fuselage panels, wing panels, radomes, empennage skins, or shear webs

Question 5

What procedures should be used to prevent damage to the hole when drilling through plexiglass?

Answer 5

The plexiglass should be backed with wood and the feed slowed as a drill points breakthrough. A drillbit that should be modified to a 60° tip angle, the cutting edge 280 rake angle, and the back lip clearance angle increased to a 12 to 15°.

Question 6

What calculations must be made when bending sheet metal?

Answer 6

Set-back and bend allowance

Question 7

what factors are used to determine setback?

Answer 7

Setback = radius + thickness

Question 8

when bending sheet metal, how should the grain be in relation to the band?

Answer 8

The grain should be perpendicular to the bend.

Question 9

what is a bend tangent line?

Answer 9

The line at which the metal starts to bend.

Question 10

what is a joggle?

Answer 10

And offset near the edge of a piece of sheet metal to allow clearance for a sheet or extrusion.

Question 11

What are several methods used in forming sheet metal?

Answer 11

Folding, bumping, crimping, shrinking, and stretching.

Question 12

What kind of metal forming is done by bumping?

Answer 12

Compound curves.

Question 13

What is crazing and how does it occur?

Answer 13

Has the appearance of spiderwebs. Hairline cracks in the surface of plastic. Caused by uneven heating, one side expanding more than the other causing excessive stress. Exposure to harmful solvents will also cause crazing.

Question 14

briefly describe the anodizing process and what purpose it serves.

Answer 14

Aluminum alloys are placed in a electrolytic bath which causes a thin film of hydroxide to form on the surface of the aluminum. This anodizing coat not only provides excellent resistance to corrosion but it also an excellent bond for paint.

Question 15

What are the proper dimensions for shop head of a rivet?

Answer 15

1.5 times the diameter in width and .5 times the diameter and height.

Question 16

When inspecting plexiglass, what should you look for?

Answer 16

Crazing and discoloration.

Question 17

What causes honeycomb structure to the laminate?

Answer 17

Moisture.

Question 18

What are the acceptable repair methods for bonded honeycomb structure that has been damaged?

Answer 18

Did to accept methods is potted repair method, and laminated glass fabric cloth overlay method (for when damage exceeds potted repair method limitations).

Question 19

What drill size should we use for the common shank rivet diameters of 3/32 inch, 4/32 inch, and 5/32 inch?

Answer 19

3/32” rivet - #40
4/32 “rivet - #30
5/32 “rivet - #21

Question 20

what type of materials are used in honeycomb construction?

Answer 20

Stainless steel, titanium, magnesium, plywood, resin impregnated paper, E-glass, nylon, or cotton cloth in various combinations.

Question 21

what is used for hole filling in a bonded honeycomb repair?

Answer 21

Potting compound.

Question 22

What is a lightening hole?

Answer 22

Holes are cut into rib sections, fuselage frames, and other structural parts to decrease weight. Flanges are pressed around the holes for strength.

Question 23

What special precautions should be observed when repairing a radome?

Answer 23

The repair must retain its strength and electrical transparency.

Question 24

What is a warp line?

Answer 24

A highlighted strand on the fabric used for ply orientation.

Question 25

What does pot life mean?

Answer 25

The length of time a resin will remain workable after the catalyst has been added.

Question 26

what is a Barcol hardness tester?

Answer 26

A device that pushes a spike into materials such as composite. The depth of penetration can be measured to determine if resins in the composite have cured.