Airframe: Section 1. Airframe Structures - I V . - Sheet Metal And Non-Metallic Structures

Front 1

For maximum strength of a formed sheet metal fitting, should the bend be made along or across the grain of the metal?

Back 1

Across the grain.

Front 2

What determines the minimum bend radius that can be used when forming a sheet metal structural fitting?

Back 2

The alloy, the metal thickness, and its hardness.

Front 3

What is meant by the neutral axis in a sheet of metal?

Back 3

A plane within the metal that neither stretches nor shrinks when the metal is being bent.

Front 4

What is a mold line in the development of a flat pattern for a formed metal part?

Back 4

An extension of the flat sides beyond the radius.

Front 5

What is the bend tangent line?

Back 5

A line in a flat pattern layout at which the bend starts.

Front 6

What is meant by setback?

Back 6

The distance the jaws of a brake must be set back from the mold line to form a bend.

Front 7

What is meant by bend allowance?

Back 7

The actual amount of metal in a bend. It is the distance between the bend tangent lines in a flat pattern layout.

Front 8

What is a sight line?

Back 8

A line drawn on a flat pattern layout within the bend allowance that is one bend radius from the bend tangent line. When the sight line is directly below the nose of the radius bar on the brake, the bend will start at the bend tangent line.

Front 9

What type of device is a Cleco fastener?

Back 9

A patented fastener that is inserted in the rivit holes and used to hold the two pieces of sheet metal together until they can be riveted.

Front 10

What is the main function of throatless shears in an aircraft sheet metal shop?

Back 10

Throatless shears are used to cut mild carbon steel up to 10–gage, and stainless steel up to 12–gage. They can be used to cut irregular curves in the metal.

Front 11

What kind of metal forming is done by a slip roll former?

Back 11

Simple curves with a large radius.

Front 12

What kind of metal forming is done by bumping?

Back 12

Compound curves in sheet metal.

Front 13

When forming a curved angle, what must be done to the flanges?

Back 13

The flanges must be stretched for a convex curve and shrunk for a concave curve.

Front 14

When hand–forming a piece of sheet metal that has a concave curve, should the forming be started in the center of the curve, or at its edges?

Back 14

Start at the edges and work toward the center.

Front 15

What is meant by a joggle in a piece of sheet metal?

Back 15

A joggle is a small offset near the edge of a piece of sheet metal that allows the sheet to overlap another piece of metal.

Front 16

What is the minimum edge distance allowed when installing rivets in a piece of aircraft sheet metal structure?

Back 16

Two times the diameter of the rivet shank.

Front 17

What is the recommended transverse pitch to use when making a riveted two row splice in a piece of sheet metal?

Back 17

Three–fourths of the distance between the rivets in the rows.

Front 18

Why should aluminum alloy rivets be driven with as few blows as is practical?

Back 18

Excessive hammering will work–harden the rivets and make them difficult to drive.

Front 19

What determines whether a piece of sheet metal should be dimpled or countersunk when installing flush rivets?

Back 19

The thickness of the sheet. Countersinking should be done only when the thickness of the sheet is greater than the thickness of the rivet head.

Front 20

What type of metal should be hot–dimpled?

Back 20

7075–T6, 2024–T81 aluminum alloys, and magnesium alloys should be hot–dimpled.

Front 21

What should be done to protect a riveted joint between aluminum alloy and magnesium alloy from corrosion?

Back 21

Coat the faying surface with a corrosion–inhibiting primer, dip the rivets in the primer and drive them while the primer is wet.

Front 22

Which stringer attached to a wing skin would require the greatest number of rivets for a splice?

Back 22

A stringer in the lower surface.

Front 23

What type of rivet may be used to replace a round head rivet in the aircraft structure?

Back 23

A universal head rivet.

Front 24

How long should a rivet be to join two pieces of sheet metal?

Back 24

The combined thickness of the metal sheets plus 1–1/2 times the rivet shank diameter.

Front 25

Should a riveted joint fail in shear or in bearing?

Back 25

It should fail in shear. The rivets should shear before the sheet tears at the rivet holes.

Front 26

What is the purpose of the beehive spring on a rivet gun?

Back 26

It holds the rivet set in the gun and allows the gun to vibrate the set.

Front 27

How can water entrapped in a honeycomb structure be detected?

Back 27

By the use of radiographic inspection.

Front 28

What effect can entrapped moisture have on metal honeycomb structure?

Back 28

Entrapped water can cause corrosion.

Front 29

What is the simplest way to detect delamination in a composite structure?

Back 29

Tap the surface with the edge of a coin. If the material is sound, the tapping will result in a clear ringing sound; but if it is delaminated, the sound will be a dull thud.

Front 30

What type of nondestructive inspection is suitable for detecting internal damage in honeycomb material?

Back 30

Ultrasonic inspection.

Front 31

What kind of repair can be made to a small damage of the core material and one face sheet of a piece of aluminum alloy honeycomb structure?

Back 31

A potted compound repair.

Front 32

What special precautions must be taken when repairing a radome?

Back 32

Nothing must be done to the radome that will affect its electrical transparency or its aerodynamic strength.

Front 33

How do you grind the point of a twist drill that is to be used for drilling transparent acrylic material?

Back 33

The cutting edge should be dubbed off to a zero rake angle, and the included angle of the tip should be ground to 140 degrees.

Front 34

What is a warp clock in a structural repair manual?

Back 34

An alignment indicator to show the orientation of the plies of a composite material. The ply direction is shown in relation to a reference direction.

Front 35

What are two advantages of laminated construction over riveted sheet metal?

Back 35

Light weight and rigidity.

Front 36

What are two popular types of core material used in laminated structure?

Back 36

Foam and honeycomb.

Front 37

What are two popular types of matrix material used in laminated structure?

Back 37

Polyester and epoxy resins.

Front 38

What are the two parts of a polyester matrix material?

Back 38

Resin and catalyst.

Front 39

What are the two parts of an epoxy matrix material?

Back 39

Resin and hardener.

Front 40

What are the two types of resins used in aircraft construction?

Back 40

Thermoplastic and thermosetting.

Front 41

What is necessary to cure a thermosetting resin?

Back 41

Heat.

Front 42

What are three materials that may be used to reinforce the matrix material for aircraft structure?

Back 42

Fiberglass, Kevlar®, and graphite.

Front 43

What is meant by unidirectional fabric?

Back 43

A fabric in which all of the major fibers run in the same direction.

Front 44

What is meant by the ribbon direction of a honeycomb material?

Back 44

The direction in a piece of honeycomb material that is parallel to the length of the strips of material that make up the core.

Front 45

What are two types of repair to a damaged honeycomb core composite material?

Back 45

Room–temperature cure repair and hot–bond repair.

Front 46

What is meant by the shelf life of a material?

Back 46

The normal length of time a material can be expected to keep its usable characteristics if it is stored and not used.

Front 47

What is meant by the pot life of a resin?

Back 47

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

Front 48

What document lists the safety hazards associated with a resin used in composite structure?

Back 48

The Material Safety Data Sheet for that resin.

Front 49

Of what class of resins are aircraft windows and windshields made?

Back 49

Thermoplastic.

Front 50

What type of transparent plastic material is used for most aircraft windshields?

Back 50

Acrylic plastic.

Front 51

How should sheets of transparent plastic material be stored?

Back 51

Leave the protective paper on the material and store it tilted approximately 10° from the vertical.

Front 52

How tight should the screws be tightened when installing an acrylic windshield in a channel?

Back 52

Tighten the screw to a firm fit and back it off one full turn.

Front 53

What is meant by crazing of transparent plastic material?

Back 53

Tiny hair–like cracks that may not extend all of the way to the surface. Crazing is caused by stresses or chemical fumes.

Front 54

What type of material is used to remove surface damage to a piece of acrylic resin?

Back 54

Micro–Mesh® abrasive sheets.