Sheet metal Flashcards
Select the alternative which best describes the function of the flute section of a twist drill
Forms the cutting edges of the drill point
Rivet gauge, or transverse pitch is the distance between the
Centers of rivets in adjacent rows.
Clad aluminum alloys are used in aircraft because they
Have surface layers of pure aluminum or aluminum alloy bonded to the core material to inhibit corrosion.
MS20426AD-6-5 indicates a countersunk rivet which has
An overall length of 5/16 inch.
Which rivet is used for riveting nickel-steel alloys?
Monel
What should be the included angle of a twist drill for soft metals?
90 degrees
The monocoque fuselage relies largely on the strength of
skin or covering
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
A piece of stuck that is to be bent to a closed angle of 15 degrees must be bent through an angle of
165 degrees
(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
What reference tool is used to determine how the fiber is to be oriented for a particular ply of fabric?
Warp clock (or compass)
Cabin upholstery materials installed in current standard category airplanes must
Be at least flame resistant.
When an MS20470D rivet is installed, its full shear strength is obtained
Only after a period of age hardening.
When conducting a tap test on a composite panel, which of the following sounds would indicate delamination?
Dull thud
(Refer Figure 1.) Which of the rivets shown will accurately fit the conical depression made by a 100 degree countersink?
1
Which of the following drill bit types work best when drilling an aramid fiber (kevlar) composite laminate?
Carbide W-point
The primary alloying agent of 2024-T3 is indicated by the number
2
A well-designed rivet joint will subject the rivets to
Shear loads
What is the material layer used within the vacuum bag pressure system to absorb excess resin during curing called?
Bleader
A category of plastic material that is capable of softening or flowing when reheated is described as a
Thermoplastic
A main difference between lockbolt/huckbolt tension and shear fasteners (other than their application) is in the
Number of locking collar grooves
Mild steel rivets are used for riveting
steel parts
Which of the following are generally characteristics of carbon/graphite fiber composites?
1) Flexibility
2) Stiffness
3) High Compression Strength
4) Corrosive effect in contact with aluminum
5) Ability to conduct electricity
2,3, and 4
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
If it is necessary to compute a 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 type of bit should be used to drill holes in plexiglass?
A specifically modified twist drill
Repairing advanced composites using materials and techniques traditionally used for fiberglass repairs is likely to result in
An unairworthy repair
Which of the following, when added to wet resins, provide strength for the repair of damaged fastener holes in composite panels?
1) Microballoons
2) Flux
3) Chopped Fibers
2 and 3
Which is an identifying characteristic of acrylic plastics?
Zinc chloride will have no effect
Fiberglass damage that extends completely through a laminated sandwich structure
May be repaired
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 general rule for finding the proper rivet diameter is
Three times the thickness of the thickest sheet
What type loads cause the most rivet failures?
Shear
Under certain conditions, type A rivets are not used because of their
low strength characteristics
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
When inspecting a composite panel using the ring test/tapping method, a dull thud may indicate
Separation of the laminates
What is the purpose of refrigerating 2017 and 2024 aluminum alloy rivets after heat treatment?
To retard age hardening
Which of these methods may be used to inspect fiberglass/honeycomb structures of entrapped water?
1) Acoustic emission monitoring
2) x-ray
3) backlighting
2 and 3
On a sheet metal fitting layout with a single bend, allow for stretching by
Subtracting the setback from both legs
Which part of the 2017-T36 aluminum alloy designation indicates the primary alloying agent used in its manufacture
2
What is the minimum spacing for a single row of aircraft rivets
Three times the diameter of the rivet shank
When drilling stainless steel, the drill used should have an included angle of
140 degrees and turn at a low speed
(Refer to figure 4.) The amount of material required to make the 90 degree bend is
0.3436 inch
Sandwich panels made of metal honeycomb construction are used on modern aircraft because this type of construction
Has a high strength to weight ratio.
Rivet pitch is the distance between the
Centers of adjacent rivets in the same row
What is the purpose of a gusset or gusset plate used in the constitution and repair of aircraft structures?
To join and reinforce intersecting structural members
When necessary, what type of cutting fluid is usually acceptable for machining composite laminates?
Water only
Which of the following need not be considered when determining minimum rivet spacing?
Rivet length
Alloy 2117 rivets are heat treated
By the manufacturer and do not require heat treatment before being driven.
When making repairs to fiberglass, cleaning of the area to be repairs is essential for a good bond. The final cleaning should be made using
MEK (methyl ethyl ketone)
The Dzus turnlock fastener consists of a stud, grommet, and receptacle. The stud diameter is measured in
sixteenths of an inch
The coefficient of expansion of most plastic enclosure materials is
Greater than both steel and aluminum
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 form the atmosphere
A single-loop 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 comparing the machining techniques for stainless steel sheet material to those for aluminum alloy sheet, it is normally considered considered good practice to drill the stainless steel at a
Lower speed with more pressure applied to the drill
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
Fiberglass laminate damage that extends completely through one facing and into the core
Requires the replacement of the damaged core and facing
Joggles in removed rivet shanks would indicate partial
Shear failure
The preferred way to make permanent repairs on composites is by
Laminating on new repair plies
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
1/4 inch
Composite fabric material is considered to be the strongest in what direction?
Warp
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
(Refer to Figure 6.) What is dimension D?
Setback = .252
Bend allowance = .345
4.182
The flat layout or blank length of a piece of metal from which a simple L-shaped bracket 3 inches by 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 most important factors needed to make a flat pattern layout are
Radius, thickness, and degree of bend
Which rivet is used for riveting magnesium alloy structures
5056 aluminum
Metal fasteners used with carbon/graphite composite structures
Must be constructed of material such as titanium or corrosion resistant steel
The strength and stiffness of a properly constructed composite buildup depends primarily on
The orientation of the plies to the load direction.
How many of the following are benefits of using microballoons when making repairs to laiminated 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
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
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
If no scratches are visible after transparent plastic enclosure materials have been cleaned, their surfaces should be
Covered with a thin coat of wax
The length of time that a catalyzed resin will remain in a workable state is called the
Pot life
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 that similar repairs to the upper surface.
The monocoque fuselage relies largely on the strength of
Skin or covering
Threaded rivets (rivnuts) are commonly used to
Attach parts or components with screws to sheet metal
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
What is the minimum edge distance allowed for aluminum alloy sing lap sheet splices containing
The minimum edge distance for the single row is equal to that for the multiple row.
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
A potted compound repair on honeycomb can usually be made on damages less than
1 inch diameter
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
The aluminum alloys used in aircraft construction are usually hardened by which method?
Heat treatment
Which is considered good practice concerning the installation of acrylic plastics?
When rivets are used, adequate space or other satisfactory means to prevent excessive tightening of the frame to the plastic should be provided.
Which rivet is used for riveting nickel-steel alloys?
Monel
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.
What type of bit should be used to drill holes in plexiglas?
A specifically modified twist drill
A factor which determines the minimum space between rivets is
The diameter of the rivets being used
Select the alternative which best describes the function of the flute section of a twist drill
Forms the cutting edges of the drill point
(Refer to Figure 3.) Which is the grip length of the flush rivet?
3
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 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.
When straightening members made of 2024-T4, you should
Straighten cold and reinforce
If a streamline cover plate is to be hand formed using a form bock, 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.
(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
The sharpest bend that can be placed in apiece of metal without critically weakening the part is called the
Minimum radius of the bend
The shop head of a rivet should be
One and one-half times the diameter of the rivet shank.
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 part of 2024-T3 aluminum alloy indicates the temper designation?
T3
A DD rivet is heat treated before use to
Soften to facilitate riveting
On a semimonocoque fuselage, the skin is reinforced by longitudinal structural members called
Longerons and stringers
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 rivet set used to drive MS20470 rivets should
Have a slightly greater radius than the rivet head
The dimensions of an MS20430AD-4-8 rivet are
1/8 inch in diameter and 1/2 inch long
Most rivets used in aircraft construction have
Dimples
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.
How does acoustic emission testing detect detetcs in composite materials?
By picking up the “noise” of any deterioration that may be present.
(Refer to Figure 5.) What is the flat layout dimension?
6.8 inches
Shallow scratches on sheet metal may be required by
Burnishing
The length of a rivet to be used to join a sheet of .032 inch inch and .064 inch aluminum alloy should be equal to
One and one-half times the rivet diameter plus .096 inch.
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
The classification for high tensile strength fiberglass used in aircraft structures is
S-glass
The markings on the head of a Dzus fastener identify the
Body diameter, type of head, and length of the fastener.
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 rivets should be selected to join two sheets of .032 inch aluminum?
MS20470AD-4-4
Which of the following drill bit types work best when drilling an aramid fiber (Kevlar) composite laminate?
Carbide W-point
A piece of sheet metal is bent to a certain radius . The curvature of the bend is referred to as the
Bend radius
(Refer to Figure 4.) The length of flat A is
3.750 inches
The part of a replacement honeycomb core that must line up with the adjacent original is the
Ribbon direction
A potted compound repair on honeycomb can usually be made on damages less than
1 inch in diameter
One of the main advantages of Hi-lok type fasteners over earlier generations is that
They can be installed with ordinary hand tools.
Cabin upholstery materials installed in current standard category airplanes must
Be at least flame resistant
What is the most common method of cementing transport plastics
Soak method
Aircraft structural units, such as spars, engine supports etc, which have been built up from sheet metal, are normally
Repairable, using approved methods.
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.
You can distinguish between aluminum and aluminum alloy by
Testing with a 10 percent solution of caustic soda.
What is the minimum edge distance for aircraft rivets?
Two times the diameter of the rivet shank
(Refer to Figure 2.) Select the preferred drawing for proper countersinking
1
When balsa wood is used to replace a damaged honeycomb core, the plug should be cut so that
The grain is perpendicular to the skin.
Which part(s) of a semi-monocoque fuselage prevent(s) tension and compression from bending the fuselage?
Longerons and stringers
Heat-treated rivets in the D and DD series that are not driven within the prescribed time after treatment of removal from refrigeration
Must be reheat treated before use.
Rivet gauge, or transverse pitch is the distance between the
Centers of rivets in adjacent rows.
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.
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.
What should be the included angle of a twist drill for hard metal?
118 degrees.
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.
The classification for fiberglass reinforcement material that has high resistivity and is the most common is
E-glass
The general rule for finding the proper rivet diameter is
Three times the thickness of the thickest sheet
How many MS20470 AD-4-6 rivets will be required to attach a 10x5 inch plate, using a single row of rivets, minimum edge distance, and 4D spacing?
56
The installation of cherry mac and olympic-Lok rivets is accomplished by utilizing
A pulling tool
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 fit, then backed off one full turn.
The strength and stiffness of a properly constructed composite buildup depends primarily on
The orientation of the plies to the load direction.
Parts fabricated from Alclad 024-T3 aluminum sheet stock must have all
Scratches, kinks, tool marks, nicks, etc., must be held to a minimum.
The Dzus turnlock fastener consists of a stud, grommet, and receptacle. The stud length is measured in
Hundredths of an inch.
