Sheet metal and Non-Metallic Structures
When straightening members made of 2024-T4, you should
straighten cold and reinforce.
(Refer to Figure 4.) The amount of material required to make the 90 degree bend is
0.3436 inch.
(Refer to Figure 2.) Select the preferred drawing for proper countersinking.
1
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 dimensions of an MS20430AD-4-8 rivet are
1/8 inch in diameter and 1/2 inch long.
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.
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 degree 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 degrees
Which part of the 2017-T36 aluminum alloy designation indicates the primary alloying agent used in its manufacture?
2
Which rivet may be used as received without further treatment?
2117-T3
(Refer to Figure 3.) Which is the grip length of the flush rivet?
3
(Refer to Figure 5.) what is the length of flat A?
3.7 inches.
(Refer to Figure 4.) The length of flat A is
3.750 inches.
(Refer to Figure 6.) What is dimension D? Setback = .252 Bend Allowance = .345
4.182
(Refer to Figure 7.) What is dimension F? Setback 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.
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" plate, using a single row of rivets, minimum edge distance, and 4D spacing?
56
(Refer to Figure 5.) What is the flat layout dimension?
6.8 inches.
What should be the included angle of a twist drill for soft metals?
90 degrees
(Refer to Figure 6.) 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
What type of bit should be used to drill holes in Plexiglass?
A specially modified twist drill.
What should be the included angle of a twist drill for hard metal?
118 degrees
The primary alloying agent of 2024-T3 is indicated by the number
2
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.
Rivet Rule #3
ED = 2d - 4d Preferred ED = 2.5d
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.
Which rivets should be selected to join two sheets of .032-inch aluminum?
MS20470AD-4-4
Which rivet is used for riveting nickel-steel alloys?
Monel.
A piece of sheet metal is bent to a certain radius. The curvature of the bend is referred to as the
bend radius.
What type loads cause the most rivet failures?
shear
The general rule for finding the proper rivet diameter is
three times the thickness of the thickest sheet.
(Refer to Figure 1.) Which of the rivets shown will accurately fit the conical depression made by a 10 degree countersink?
1 - 130 degree
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
Rivet Rule #2
Length = total thickness of material joined + 1.5d Find nearest 16th"
Which part(s) of a semi-monocoque fuselage prevent(s) tension and compression from bending the fuselage?
Longerons and stringers.
Which statement is true regarding a cantilever wing?
No external bracing is needed.
Rivet Rule #4
Pitch = 3d - 12d Preferred Pitch = 6d - 8d
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.
Which of the following need not be considered when determining minimum rivet spacing?
Rivet length.
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.
What is one of the determining factors which permits machine countersinking when flush riveting?
Thickness of the material is 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.
What is the purpose of a gusset plate used in the construction and repair of aircraft structures?
To join and reinforce intersection structural members.
What is the purpose of refrigerating 2017 and 2024 aluminum alloy rivets after heat treatment?
To retard age hardening.
Rivet Rule #5
Transverse Pitch (Guage) = 75% of Pitch, staggered rows only
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.
The installation of Cherrymax and Olympic-Lok rivets is accomplished by utilizing
a pulling tool.
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.
Clad aluminum alloys are used in aircraft because they
are less subject to corrosion than uncoated aluminum alloys.
Threaded rivets (Rivnuts) are commonly used to
attach parts or components with screws to sheet metal.
The markings on the head of a Dzus fastener identify the
body diameter, type of head, and 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 gauge, or transverse pitch is the distance between the
centers of rivets in adjacent rows.
Rivet Rule #1
diameter (d) = 3 x thickest sheet. Find nearest 32nd"
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.
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.
A rivet set used to drive MS20470 rivets should
have a slightly greater radius than the rivet head.
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.
Longitudinal (fore and aft) structural members of a semi-monocoque fuselage are called
longerons and stringer.
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.
The sharpest bend that can be placed in a piece of metal without critically weakening the part is called the
minimum radius of bend.
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.
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.
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 on-half times the rivet diameter plus .096 inch.
The shop head of a rivet should be
one and one-half times the diameter of the rivet shank.
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.
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.
Hole filling fasteners (for example, MS20470 rivets) should not be used in composite structures primarily because of the
possibility of causing delamination.
The most important factors needed to make a flat pattern layout are
radius, thickness, and degree of bend.
Aircraft structural units, such as spars, engine supports, etc., which have been built up from sheet metal, are normally
repairable, using approved methods.
Parts fabricated from Alclad 2024-T3 aluminum sheet stock must have all
scratches, kinks, tool marks, nicks, etc., held to a minimum.
Joggles in removed rivet shanks would indicate partial
shear failure.
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
The monocoque fuselage relies largely on the strength of
skin or covering.
A DD rivet is heat treated before use to
soften to facilitate riveting.
The identifying marks on the heads of aluminum alloy rivets indicate the
specific alloy used in the manufacture of the rivets.
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.
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% 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 bend will be 90 degrees to the grain of the sheet.
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.
One of the main advantages of Hi-Lok type fasteners over earlier generations is that
they can be installed with ordinary hand tools.
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.
Which of the folloing drill bit types work best when drilling an aramid fiber (Kevlar) composite laminate?
Carbide W-Point
