PrepWare Sheet Metal

Clad aluminum alloys are used in aircraft because they?

Are less subject to corrosion than uncoated aluminum alloys. Clad aluminum alloys are used in aircraft construction because they are less subject to corrosion than uncoated aluminum alloys. Pure aluminum which is not susceptible to corrosion is used to coat a sheet of high-strength aluminum alloy to protect it from corrosion.

Threaded rivets (Rivnuts) are commonly used to?

Attach parts or components with screws to sheet metal. Rivnuts are a special type of blind rivet whose shank has internal threads. When the Rivnut is upset in a piece of thin sheet metal, the threaded shank acts as a nut to receive a machine screw. Rivnuts were originally designed to attach deicer boots to thin sheet metal win and empennage leading edges.

Alloy 2117 rivets are heat treated.

By the manufacturer and do not require heat treatment before being driven. Alloy 2117 rivets, which are called AD rivets, are heat treated by the manufacturer. They do not require any further heat treatment before they are driven.

Rivet gauge, or transverse pitch is the distance between the

Centers of rivets in adjacent rows. Rivet gauge, or transverse pitch, is the distance between the centers of rivets in adjacent rows.

A factor which determines the minimum space between rivets is the?

Diameter of the rivets being used. Rivet spacing is based on the diameter of the rivet shank it is expressed in terms of rivet diameters

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

Forms the cutting edges of the drill point. One of the functions of the flutes cut into the shank of a twist drill is to form the cutting edges of the drill point.

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

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

Fretting corrosion is occurring between the rivets and the skin. A smoky residue streaming back from some of the rivets in an aircraft structure is normally an indication of fretting corrosion. An extremely small amount of relative movement between the rivet and the surface of the rivet hole. It acts as an abrasive, wearing off more oxides. These loosened oxides work their way out between the skin and the rivet and resemble smoke streaming out from the rivet.

A rivet set used to drive MS20470 rivets should

Have a slightly greater radius than rivet head. The rivet set used to drive AN470 or MS20470 universal head rivets should have a radius slightly larger than the radius of the rivet head. This larger radius allows the hammering action of the rivet gun to be directly on the crown of the rivet.

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

If genuine rivet tipping has occurred, groups of consecutive rivet heads will be tipped in the same direction. If the structure has actually been damaged, this would be indicated by groups of consecutive rivet heads being tipped in the same direction caused by a major deflection of the skin under load.

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. When drilling stainless steel, you should use a drill with a larger included angle. Use a lower speed and more pressure than you would use for aluminum alloy.

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 rivet length used to join two sheets of metal should be equal to the total thickness of the metal being joined plus 1-1/2 times the diameter of the rivet. The total thickness of the material being joined is 0.096 inch the length of the rivet should be 1-1/2 times the rivet diameter plus 0.096 inch.

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 place under the brake

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

Only after a period of age hardening. An MS20470D rivet is an "icebox" rivet, and it must be heat-treated before it is driven. After it is removed from the quench bath it is stored in a subfreezing refrigerator to keep it soft until it is ready to be driven. After it is driven, it age hardens. It regains approximately half of its strength in one hour and its full strength in four days.

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

Repairable, using approved methods. Aircraft structural units which are built up from sheet metal are normally repairable, using procedures recommended by the manufacturer of the airframe and approved by the FAA

Parts fabricated from Alclad 2024-T3 aluminum sheet stock must have all?

Scratches, kinks, tool marks, nick, etc., held to a minimum. When fabricating parts from Alclad 2024-T3 aluminum sheet stock,. be sure that all damaged such as scratches, kinks, tool marks, and nicks are held to a minimum to prevent exposing the alloy core through the damaged pure aluminum surface coating.

What type loads cause the most rivet failures

Shear A shear load which causes most rivet failures is one that tries to cut a rivet by shearing it. Rivets are designed to e used in joints loaded in shear only

Joggles in removed rivet shanks would indicate partial

Shear failure A joggle in the shank of a rivet that has been removed from a damaged aircraft structure indicates that the rivet joint has failed in shear

A well designed rivet joint will subject the rivet to?

Shear loads A properly designed rivet joint has the major part of the load in the rivets as a shear load.

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

Sixteenths of an inch. The diameter of the stud of a Dzus fastener is measured in 1/16-inch increments.

The monocoque fuselage relies largely on the strength of

Skin or covering The greatest amount of strength in a monocoque fuselage is derived from the skin or covering.

A DD rivet is heat treated before use to

Soften to facilitate riveting. DD or 2024-T riveting are heat treated before they are driven to soften them so they will not split when they are driven.

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

Specific alloy used in the manufacture of the rivets. Identifying mark on the head of an aluminum alloy rivet indicates the specific alloy used in the manufacture of the rivet.

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 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. When using the bumping operation to form a compound curve in a piece of soft aluminum use light blows of the mallet to work the material down gradually from the edges. Remember that the object of the bumping process is to work the material into shape by stretching it rather than by forcing it into the form with heavy blows. Always start bumping near the edge of the form. Never start in the center.

If a new safety belt is to be installed in an aircraft, the belt must conform to the strength requirements in which document?

TSO C22. Safety belts approved for installation in aircraft may be identified by the marking TSO C22 on the belt or by the military designation number for the belt. Military belts are approved for installation, because their requirements meet or exceed those of TSO C22.

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

The can be installed with ordinary hand tools. Hi-Lok fasteners are a new form of Hi-Shear fasteners that can be installed with ordinary hand tools rather than requiring the special riveting tools. The pin is installed in an interference-fit hole and the collar screwed down over the threaded end. The pin is held with an Allen wrench and the collar is screwed down, using an open-end wrench until the proper torque is reached. At this point, the hex shear-nut portion of the collar will break off.

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 length of the fastener. Dzus fasteners are identified by marks on the head of the stud. A letter identifies the type of head, a number identifies the body diameter in 1/16-inch increments, and another number identifies the stud length in hundredths of an inch.

Shallow scratches in sheet metal may be repaired by?

Burnishing. Shallow scratches in sheet metal may be repaired by burnishing.

Which of the following drill bit types work best when drilling an aramid fiber (Kevlar) composite laminate?

Carbide W-Point. A carbide w-point bit (better known as a brad-point bit) is used to drill holes in aramid fiber (Kevlar) composite laminate to keep the hole free of the fuzzy fibers that other drilling methods leave behind in the hole.

Rivet pitch is the distance between the

Centers adjacent rivets in the same row. Rivet pitch is the distance between the centers of adjacent rivets in the same row.

Most rivets used in aircraft construction have

Dimples. Most rivet used in aircraft construction and repair are made of aluminum alloy 2117. 2117 rivets are identified by a dimple in the center of the manufactured head.

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. When removing a solid shank rivet from a piece of aircraft structure, drill to the base of the manufactured head with a drill one size smaller than the rivet shank. Insert a pin punch to drive the rivet shank from the skin.

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

Heat treatment.

Unless otherwise specified the radius of a bend is the

Inside radius of the metal being formed

Which part(s) of a semi-monocoque fuselage prevent(s) tension and compression from bending the fuselage?

Longerons and stringers In a semimonocoque fuselage, the primary bending loads are taken by the longerons, which usually extend across several points of support. The longerons are supplemented by other longitudinal member called stringers.

Longitudinal (fore and aft) structural members of a semi-monocoque fuselage are called?

Longerons and stringers. The longitudinal structural members of a semimonocoque fuselage are called longerons and stringers.

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

Low strength characteristics. Type A rivets (commercially pure aluminum rivets) are not used for aircraft structural repairs because of their low-strength characteristics.

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. Repairs or splices to the stringers on the lower surface of a stressed skin metal wing are permitted, but since the lower surface of the wing is under a tensile load in flight, these repairs are more critical with regard to tensile strength than repairs to the upper surface.

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. One precaution to be observed when riveting together dissimilar metals is to place a nonconductive separator between the two surfaces. This separator prevents the migration of electrons between the areas of electrode potential difference

The most important factors needed to make a flat pattern layout are

Radius, thickness and degree of bend

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

Rivet length. The length of the rivet does not enter into the determination of the minimum rivet spacing. The rivet diameter and the type and thickness of the material do determine rivet spacing.

Mild steel rivets are used for riveting

Steel parts. Mild steel rivets are used for joining steel parts

When straightening members made of 2024-T4 you should

Straighten cold and reinforce. If structural member of 2024-T4 aluminum alloy is bent, it should be straightened cold and then reinforced.

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

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. When using a reamer to enlarge a hole, always turn the reamer in the direction of cutting. If the direction of reamer motion is reversed, the reamer will be seriously dulled.

What is the minimum edge distance for aircraft rivets?

Two times the diameter of the rivet shank. The minimum edge distance for aircraft rivets ( the distance between the center of the rivet hole and the edge of the sheet) is twice the diameter of the rivet shank.

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. This problem calls for joining two pieces of 0.040 inch material using 3/32 inch rivets. The total thickness of the material is 0.080 inch. The rivet should protrude through the material for 1-1/2 diameters or 0.1406 inch. the nearest standard rivet to this length is 1/4 inch long (0.250 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 The first dash number in the rivet identification gives the rivet diameter in 1/32 inch increments. The second dash number gives the rivet length in 1/16 inch increments. An MS20430AD-4-8 rivet is 4/32 inch (1/8 inch) in diameter and 8/16 inch (1/2inch) long.

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

118 degrees. For most drilling, including that for hard metal, the cutting angle of a twist drill is ground to an included angle of 118 degrees (59 degrees on either side of center)

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. The minimum row distance is 2-1/2 D. (D=diameter) 6-1/2D= 13/2 D Given the rivet diameter (D) specified in this question: 13/2 (1/8")= 13/6 inches total overlap.

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

140 degree and turn at a low speed. The drill used for drilling stainless steel should have a much flatter angle than a drill used for soft material. An include angle of approximately 140 degrees is good for stain-less steel. When drilling stainless steel, the drill should turn at a slow 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 degrees. A closed angle is an angle that has been bent beyond 90 degrees in order to form a closed angle of 15 degrees the sheet must be bent through an angle of 165 degrees ( 180 - 15 = 165)

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

2 The primary alloying agent in 2017-T36 aluminum alloy is copper which is identified by the digit 2

The primary alloying agent of 2024-T3 is indicated by the number

2 The primary alloying agent of 2024-T3 aluminum alloy is copper, which is identified by the first digit 2.

Which rivet may be used as received without further treatment?

2117-T3. A 2117-T3 rivet is known as an AD rivet. It may be driven as received, without further heat treatment.

Which is the grip length of the flush rivet?

3. The grip length of a rivet is the total thickness of the material held together by the rivet.

What is the length of flat A

3.7 inches The length of flat A is its mold line length of 4.00 inches minus the setback. The setback is the thickness of the metal (0.062 inch) plus the bend radius ( 0.250 inch) or 0.312 inch. The length of flat A is 4.00 - 0.312 = 3.688 inches

What is dimension D? setback=.252 bend allowance= .345

4.182

What is dimension F? set back at D .095 Setback at E =.068 bend allowance at D = .150 bend allowance at E= .112

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 Each of the two sheets of material to be riveted together has a thickness of 0.0625 inch. The total thickness of the material for 1-1/2 diameters, which is 0.1875 inch. The total length of the rivet must be 0.3125 inch which is 5/16 inch.

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

56. The plate is 10 inches ling and 5 inches wide. The rivets have a diameter of 1/8 inch and there is an edge distance of two rivet diameters. This requires two rows of rivets 9-1/2 inches ling and two rows that are 4-1/2 inches long. the total length of the rivet seams is 28 inches. If the rivets are spaced every 1/2 inch (4D spacing), 56 rivets are needed.

What is the flat layout dimension

6.8 inches The dimension of flat A is 3.688 inches The dimension of Flat B is 2.688 inches Using the bend allowance formula, we find that 0.441 inch of material is used to make the bend. The total layout dimension is 3.688 + 2.688 + 0.441=6.814 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

7/16 inch The two sheet of material to be riveted together have a total thickness of 0.096 inch. The rivet installed in a no. 30 hole is a 1/8 inch rivet it should extend through the material a distance of 0.1875 inch. The total length of the rivet must be 0.096 + 0.1875 =0.2835. The nearest standard rivet length to this is 5/16 inch (0.3125 inch)

What type of bit should be used to drill holes in Plexiglas?

A specific modified twist drill. When holes are to be drilled completely through Plexiglas, the standard twist drill should be modified to a 60 degree tip angle, the cutting edge ground to a zero rake angle, and the back lip clearance angle increased to 12 degrees to 15 degrees.

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

1. The angle between the head and the shank of rivet 1 is 130 degrees on each side (260 degrees on both sides) The angle formed by the rivet head is 100 degrees (360 degrees-260 degrees) Which is the standard angle for the cutter in an aircraft rivet countersink.

Select the preferred drawing for proper countersinking,

1. The type of countersinking shown in view 1 is preferred. The type of countersinking shown in view 2 is acceptable. The type of countersinking shown in view 3 is not acceptable.

Which rivet is used for riveting magnesium alloy structures

5056 aluminum To prevent corrosion in magnesium structure, 5056 aluminum alloy rivets should be used. Magnesium is the chief alloying agent in 5056 aluminum alloy

What shoul be the included of a twist drill for soft metals

90 degree

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

90 degrees. For drilling soft metals, an included angle of about 90 degrees (45 degrees either side of center) is suitable. For normal metals, an angle of 118 degrees (59 degrees on either side of center) is considered the standard lip angle.

The installation of Cherrymax and Olympic-Lok rivets is accomplished by utilizing?

A pulling tool. Cherrymax and Olympic-Loc rivets are types of blind rivets that are installed by inserting them into hole and pulling the stem with a special pulling tool. When the stem is pulled, a taper swells the end of the shank and upsets it. Continued pulling breaks the stem off and leaves part of it in the hollow shank to reinforce it.

Determine the dimensions of A,B, C in the flat layout

A.748, B.1.496, C.1.248

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 AN MS20426AD-6-5 rivet is countersunk head rivet made of 2117 aluminum alloy. It has a diameter of 6/32 inch (3/16 inch) and an overall length, including the head of 5/16 inch

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. To prevent undue wear on the file, when filing any metal other than lead or soft aluminum, apply pressure only during the forward stroke. Relieve the pressure during the return stroke.

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 bend will be 90 degrees to the grain of the steel.

What is the minimum edge distance allowed for aluminum alloy single lap sheet splices containing a single row of rivets as compared to a joint with multiple rows, all rivets being equal in diameter?

The minimum edge distance for the single row is equal to that for the multiple row. The edge distance allowed for an aluminum alloy single lap sheet splice is the same whether a single row of rivets or if a multiple row of rivets is used. This distance is 2 x the diameter of the rivet being used.

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. When repairing a small hole in a metal stressed skin, the rivets should take all the stress from the skin and carry it into the patch. On the opposite side of the damage, this stress is carried back into the skin. The shear strength of the riveted joints should be slightly less than the bearing strength of the skin. if a failure should occur, it will be a shear failure of the rivets, rather than a bearing failure of the skin.

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

Thickness of the metal is greater than the thickness of the rivet head. To use machine countersinking for installing a countersunk rivet, the thickness of the material must be greater than the thickness of the rivet head.

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

Three times the diameter of the rivet shank. Rivets in a single row should be spaced no closer than three times the diameter of the rivet shank (3D)

The general rule of finding the proper rivet diameter is?

Three times the thickness of the thickest sheet. A rule of thumb for determining the rivet diameter to be used for repairing aircraft sheet metal is to use a rivet whose diameter is approximately three times the thickness of the thickest sheet being joined.

What is the purpose of a gusset or gusset plate used in the construction and repair of aircraft structures?

To join and reinforce intersecting structural members. Gussets or gusset plates are used in an aircraft structure to join and reinforce intersecting structural. Gussets are used to carry stresses from one member into another at the point the members join each other.

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

To retard age hardening. 2017 and 2024 aluminum alloy rivets must be heat treated before they are driven. Immediately after they are quenched, they should be stored in a subfreezing refrigerator. Storing the rivets at the cold temperature retards their aging process and allows time to elapse between their heat treatment and their being driven.

The length of flat A

is 3.750 inches The length of flat A is its mold line length of 4.00 inches minus the setback The setback is the metal thickness ( 0.0625 inches) plus the bend radius ( 0.1875 inch) or 0.250 inch. the length of flat A is 4.00 - 0.250 = 3.750 inches

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

MS20470AD-4-4 The two pieces of material to be joined have a total thickness of 0.064 inch. The rivet used with this metal should have a diameter of about three times the thickness of the thickest sheet. This would cause us to choose a rivet with a diameter of 3 x 0.032 inch or 0.096 inch. the closest rivet to this is one with a diameter of 1/8 (0.125 inch) A 1/8 inch rivet should extend through the material for 3/16 inch or 0.1875 inch. The total length of the rivet must be 0.064 + 0.1875 or 0.2515 inch. We would choose an MS20470AD-4-4 rivet. This is a universal head rivet, 1/8 inch in diameter and 1/4 inch long

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

Minimum radius of bend

Which rivet is used for riveting nickel-steel alloys

Monel Monel rivets are used for riveting nickel steel alloys

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 Heat treated rivets of the D and DD series that are not driven within the prescribed time after heat treatment or which have been removed from refrigeration must be heat treated again before they are used. There is no specified number of time they may be reheat treated.

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

Which statement is true regarding a cantilever?

No external bracing is needed. A cantilever wing does not require any external bracing or struts. All the strength is within the wing itself.

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

Number of locking collar grooves. A lockbolt has locking grooves in its pin into which the collar is swaged. A shear lockbolt has two locking grooves, and the tension lockbolt has five grooves.

The shop head of a rivet should be?

One and one-half times the diameter of the rivet shank. The shop, or bucked, head of a rivet should have a diameter of 1-1/2 times the rivet shank diameter and a thickness of 1/2 of the shank diameter.