Chapter 2 1-30 FAA Sheet Metal

Select the preferred drawing for proper countersinking

1

Which of the rivets shown will accurately fit the conical depression made by a 100 degree countersink?

1

Which of the following are generally characteristic of aramid fiber (Kevlar) composites? 1. High tensile strength. 2. Flexibility. 3. Stiffness. 4. Corrosive effect in contact with aluminum. 5. Ability to conduct electricity.

1 and 2

Which of these methods may be used to inspect fiberglass/honeycomb structures for entrapped water? 1. Acoustic emission monitoring. 2. X-ray 3. Backlighting

1 and 2

Proper pre-preg composite lay-up curing is generally accomplished by 1. applying external heat. 2. room temperature exposure. 3. adding a catalyst or curing agent to the resin. 4. applying pressure.

1 and 4

A potted compound repair on honeycomb can usually be made on damages less than

1 inch in diameter

A sheet metal repair is to be made using two pieces of 0.040-inch aluminum riveted together. All rivet holes are drilled for 3/32-inch rivets. The length of the rivets to be used will be

1/4 inch

The flat layout or blank length of a piece of metal from which a simple L-shaped bracket 3 inches by 1 inch is to be bent depends upon the radius of the desired bend. The bracket which will require the greatest amount of material is one which has a bend radius of

1/8 inch

The dimensions of an MS20430AD-4-8 rivet are

1/8 inch in diameter and 1/2 inch long

When repairing puncture type damage of a metal faced laminated honeycomb panel, the edges of the doubler should be tapered to

100 times the thickness of the metal

What should be the included angle of a twist drill for a hard metal?

118 degrees

A single-lap sheet splice is to be used to repair a section of damaged aluminum skin. If a double row of 1/8-inch rivets is used, the minimum allowable overlap will be

13/16 inch

When drilling stainless steel, the drill used should have an included angle of

140 and turn at a low speed

A piece of flat stock that is to be bent to a closed angle of 15 degrees must be bent through an angle of

165

The primary alloying agent of 2024-T36 is indicated by the number

2

Which part of the 2017-T36 aluminum alloy designation indicates the primary alloying agent used in its manufacture?

2

Which of the following, when added to wet resins, provide strength for the repair of damaged fastener holes in composite panels? 1. Microballoons 2. Flox 3. Chopped fibers

2 and 3

How many of the following are benefits of using microballoons when making repairs of laminated honeycomb panels? 1. Greater concentrations of resin in edges and corners. 2. Improved strength to weight ratio. 3. Less density 4. Lower stress concentrations

2, 3, and 4

Which of the following are generally characteristic of carbon/graphite fiber composites? 1. Flexibility. 2. Stiffness. 3. High compressive strength. 4. Corrosive effect in contact with aluminum. 5. Ability to conduct electricity.

2, 3, and 4

Which rivet may be used as received without further treatment?

2117-T3

Which is the grip length of the flush rivet?

3

What is the length of flat A

3.7 inches

The length of flat A is

3.750

What is dimension D?

4.182

What is dimension F?

5.936

A sheet metal repair is to be made using two pieces of 0.0625-inch aluminum riveted together. All rivet holes are drilled for 1/8-inch rivets. The length of the rivets to be used will be

5/16 inch

The length of rivet to be chosen when making a structural repair that involves the joining of 0.032-inch and 0.064-inch aluminum sheet, drilled with a No. 30 drill, is

5/16 inch

Which rivet is used for riveting magnesium alloy structures?

5056 aluminum

How many MS20470 AD-4-6 rivets will be required to attach a 10 x 5 inch plate, using a single row of rivets, minimum edge distance, and 4D spacing?

56

What is the flat layout dimension

6.8 inches

Which fiber to resin (percent) ratio for advanced composite wet lay-ups is generally considered the best for strength?

60:40

What should be the included angle of a twist drill for soft metals?

90 degrees

Determine the dimensions of A, B, and C in the flat layout. Setback= .252; bend allowance= .345;

A =.748; B =1.496; C = 1.248

Which is correct concerning the use of a file?

Apply pressure on the forward stroke, only, except when filing very soft metals such as lead or aluminum

Clad aluminum alloys are used in aircraft because they

Are less subject to corrosion than uncoated aluminum alloys

What is generally the best procedure to use when removing a solid shank rivet?

Drill to the base of the manufactured rivet head with a drill one size smaller than the rivet shank and remove the rivet with a punch

The classification for fiberglass reinforcement material that has high resistivity and is the most common is

E

Select the alternative which best describes the function of the flute section of a twist drill

Forms the cutting edges of the drill point

What is indicated by a black "smoky" residue streaming back from some of the rivets on an aircraft?

Fretting corrosion is occurring between the rivets and the skin

The aluminum alloys used in aircraft construction are usually hardened by which method?

Heat Treatment

Which statement is true regarding the inspection of a stressed skin metal wing assembly known to have been critically loaded?

If a genuine rivet tipping has occurred, groups of a consecutive rivet heads will be tipped in the same direction.

When making repairs to fiberglass, cleaning of the area to be repaired is essential for a good bond. The final cleaning should be made using

MEK (methyl ethyl ketene)

Which rivets should be selected to join two sheets of .032-inch aluminum?

MS20470AD-4-4

When bending metal, the material on the outside of the curve stretches while the material on the inside of the curve compresses. That part of the material which is not affected by either stress is the

Neutral line

When riveting dissimilar metals together, what precautions must be taken to prevent an electrolytic action?

Place a protective separator between areas of potential electrical difference

What precaution, if any, should be taken to prevent corrosion inside a repaired metal honeycomb structure?

Prime the repair with a corrosion inhibitor and seal from the atmosphere

Which of the following need not be considered when determining minimum rivet spacing?

Rivet length

The classification for high tensile strength fiberglass used in aircraft structures is

S

What type loads cause the most rivet failures?

Shear

Joggles in removed rivet shanks would indicate partial

Shear failure

What is the most common method of cementing transparent plastics?

Soak method

The identifying marks on the heads of aluminum alloy rivets indicate the

Specific alloy used in the manufacture of the rivets

When repairing a small hole on a metal stressed skin, the major consideration in the design of the patch should be

The shear strength of the riveted joint

What is one of the determining factors which permits machine countersinking when flush riveting?

Thickness of the material and rivet diameter are the same

What is the minimum spacing for a single row of aircraft rivets?

Three times the diameter of the rivet shank

What is the purpose of refrigerating 2017 and 2024 aluminum alloy rivets after heat treatment?

To retard age hardening.

Which procedure is correct when using a reamer to finish a drilled hole to the correct size?

Turn the reamer only in the cutting direction

What is the minimum edge distance for aircraft rivets?

Two times the diameter of the rivet shank

What reference tool is used to determine how the fiber is to be oriented for a particular ply of fabric?

Warp clock (or compass)

When necessary, what type of cutting fluid is usually acceptable for machining composite laminates?

Water only

Which is considered good practice concerning the installation of acrylic plastics?

When rivets are used, adequate spacer or other satisfactory means to prevent excessive tightening of the frame to the plastic should be provided

Which is an identifying characteristic of acrylic plastics?

Zinc chloride will have no effect

When fabricating parts from Alclad 2024-T3 aluminum sheet stock,

all scratches, kinks, tool marks, nicks, etc., must be held to a minimum

The purpose of a joggle is to

allow clearance for a sheet or an extrusion

MS20426AD-6-5 indicates a countersunk rivet which has

an overall length of 5/16 inch

Repairing advanced composites using materials and techniques traditionally used for fiberglass repairs is likely to result in

an unairworthy repair

Threaded rivets (Rivnuts) are commonly used to

attach parts or components with screws to sheet metal

A piece of sheet metal is bent to a certain radius. The curvature of the bend is referred to as the

bend radius

The markings on the head of a Dzus fastener identify the

body diameter, type of head, and the length of the fastener

Shallow scratches in sheet metal may be repaired by

burnishing

Alloy 2117 rivets are heat treated

by the manufacturer and do not require heat treatment before being driven.

Rivet pitch is the distance between the

centers of adjacent rivets in the same row

Rivet guage, or transverse pitch is the distance between the

centers of rivets in adjacent rows

If no scratches are visible after transparent plastic enclosure materials have been cleaned, their surfaces should be

covered with a thin coat of wax

If an aircraft's transparent plastic enclosures exhibit fine cracks which may extend in a network over or under the surface or through the plastic, the plastic is said to be

crazing

A factor which determines the minimum space between rivets is the

diameter of the rivets being used

Most rivets used in aircraft construction have

dimples

Fiberglass laminate damage not exceeding the first layer or ply can be repaired by

filling with a putty consisting of a compatible resin and clean, short glass fibers

If it is necessary to compute a bend allowance problem and bend allowance tables are not available, the neutral axis of the bend can be

found by adding approximately one-half of the stock thickness to the bend radius.

The coefficient of expansion of most plastic enclosure materials is

greater than both steel and aluminum

Sandwich panels made of metal honeycomb construction are used on modern aircraft because this type of construction

has a high strength to weight ratio

A rivet set used to drive MS20470 rivets should

have a slightly greater radius than the rivet head

One of the best ways to assure that a properly prepared batch of matrix resin has been achieved is to

have mixed enough for a test sample

The Dzus turnlock fastener consists of a stud, grommet, and receptacle. The stud length is measured in

hundredths of an inch

Unless otherwise specified, the radius of a bend is the

inside radius of the metal being formed

The preferred way to make permanent repairs on composites is by

laminating on new repair plies

Under certain conditions, type A rivets are not used because of their

low strength characteristics

When comparing the machining techniques for stainless steel sheet material to those for aluminum alloy sheet, it is normally considered good practice to drill the stainless steel at a

lower speed with more pressure applied to the drill

Fiberglass damage that extends completely through a laminated sandwich structure

may be repaired

The sharpest bend that can be placed in a piece of metal without critically weakening the part is called the

minimum radius of the bend

Which rivet is used for riveting nickel-steel alloys?

monel

Metal fasteners used with carbon/graphite composite structures

must be constructed of material such as titanium or corrosion resistant steel

Heat-treated rivets in the D and DD series that are not driven within the prescribed time after heat treatment or removal from refrigeration

must be reheat treated before use

A main difference between Lockbolt/Huckbolt tension and shear fasteners (other than their application) is in the

number of locking collar grooves

The length of a rivet to be used to join a sheet of .032 inch and .064 inch aluminum alloy should be equal to

one and one half times the rivet diameter plus .096 inch

The shop head of a rivet should be

one and one-half the diameter of the rivet shank

Superficial scars, scratches, surface abrasion, or rain erosion on fiberglass laminates can generally be repaired by applying

one or more coats of suitable resin (room temperature catalyzed) to the surface

The sight line on a sheet metal flat layout to be bent in a cornice or box brake is measured and marked

one radius from the bend tangent line that is placed under the brake

(1) When performing a ring (coin tap) test on composite structures, a change in sound may be due to damage or to transition to a different internal structure. (2) The extent of separation damage in composite structures is most accurately measured by a ring (coin tap) test. Regarding the above statements,

only No. 1 is true

When an MS20470D rivet is installed, its full shear strength is obtained

only after a period of age hardening.

Repairs or splices involving stringers on the lower surface of stressed skin metal wings are usually

permitted but are normally more critical in reference to strength in tension than similar repairs to the upper surface

Composite inspections conducted by means of acoustic emission monitoring

pick up the "noise" of corrosion or other deterioration occuring

Hole filling fasteners (for example, MS20470 rivets) should not be used in composite structures primarily because of the

possibility of causing delamination

The length of time that catalyzed resin will remain in a workable state is called the

pot life

Annealing of aluminum

removes stresses caused by forming

Aircraft structural units, such as spars, engine supports, etc., which have been built up from sheet, are normally

repairable, using approved methods

Fiberglass laminate damage that extends completely through one facing and into the core

requires the replacement of the damaged core and facing

The part of a replacement honeycomb core that must line up with the adjacent original is the

ribbon direction

When inspecting a composite panel using the ring test/tapping method, a dull thud may indicate

separation of the laminates

A well designed rivet joint will subject the rivets to

shear loads

The Dzus turnlock fastener consists of a stud, grommet, and receptacle. The stud diameter is measured in

sixteenths of an inch

A DD rivet is heat treated before use to

soften to facilitate riveting

When holes are drilled completely through Plexiglas, a

specially modified twist drill should be used

If a streamline cover plate is to be hand formed using a form block, a piece of dead soft aluminum should first be placed over the hollow portion of the mold and securely fastened in place. The bumping operation should be

started by tapping the aluminum lightly around the edges and gradually working down into the center.

Mild steel rivets are used for riveting

steel parts

One method of inspecting a laminated fiberglass structure that has been subjected to damage is to

strip the damaged area of all paint and shine a strong light through the structure

On a sheet metal fitting layout with a single bend, allow for stretching by

subtracting the setback from both legs

You can distinguish between aluminum and aluminum alloy by

testing with a 10 percent solution of caustic soda

When a piece of aluminum alloy is to be bent using a minimum radius for the type and thickness of material

the layout should be made so that the bent will be 90 degrees to the grain of the sheet

The strength and stiffness of a properly constructed composite buildup depends primarily on

the orientation of the plies to the load direction

A category of plastic material that is capable of softening or flowing when reheated is described as a

thermoplastic

One of the main advantages of Hi-Lok type fasteners over earlier generations is that

they can be installed with ordinary hand tools

The general rule for finding the proper rivet diameter is

three times the thickness of the thickest sheet

When installing transparent plastic enclosures which are retained by bolts extending through the plastic material and self-locking nuts, the nuts should be

tightened to a firm it, then back off one full turn

When repairing large, flat surfaces with polyester resins, warping of the surface is likely to occur. One method of reducing the amount of warpage is to

use short strips of fiberglass in the bonded repair

Cherrymax and Olympic-Lok rivets

utilize a pulling tool for installation

Composite fabric material is considered to be there strongest in what direction?

warp

What is the material layer used within the vacuum bag pressure system to absorb excess resin during curing called?

Bleeder