Sheet Metal and Non-Metallic Structures Flashcards
Rivet gauge, or transverse pitch is the distance between the…
centers of rivets in adjacent rows
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.
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.
What type of bit should be used to drill holes in Plexiglas?
A specially modified twist drill.
The part of a replacement honeycomb core that must line up with the adjacent original is the…?
ribbon direction.
A piece of sheet metal is bent to a certain radius. The curvature of the bend is referred to as the___________?
bend radius.
Parts fabricated from Alclad 2024-T3 aluminum sheet stock must have all…?
Scratches, kinks, tool marks, nicks, etc., must be held to a minimum.
Composite fabric material is considered to be the strongest in what direction?
Warp.
A well-designed rivet joint will subject the rivets to…?
shear loads.
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.
(Refer to Figure 1.) Which of the rivets shown will accurately fit the conical depression made by a 100° countersink?
130 degree
Which statement is true regarding a cantilever wing?
No external bracing is needed.
Which statement is true regarding a cantilever wing?
No external bracing is needed
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.
Which rivets should be selected to join two sheets of .032-inch aluminum?
MS20470AD-4-4.
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 is the minimum spacing for a single row of aircraft rivets?
Three times the diameter of the rivet shank.
The aluminum alloys used in aircraft construction are usually hardened by which method?
Heat treatment.
If no scratches are visible after transparent plastic enclosure materials have been cleaned, their surfaces should be…?
Covered with a thin coat of wax.
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 of the following are generally characteristic of aramid fiber (Kevlar) composites?
- High tensile strength.
- Flexibility.
- Stiffness.
- Corrosive effect in contact with aluminum.
- Ability to conduct electricity.
High Tensile strength and Flexibility
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.
When necessary, what type of cutting fluid is usually acceptable for machining composite laminates?
Water only.
What is the minimum edge distance for aircraft rivets?
The times the diameter of the rivet shank.
Proper pre-preg composite lay-up curing is generally accomplished by
- applying external heat.
- room temperature exposure.
- adding a catalyst or curing agent to the resin.
- applying pressure.
applying external heat and applying pressure
Which is correct concerning the use of a file?
Apply pressure on the forward stroke, only, except when filling very soft metals such as lead or aluminum.
Rivet pitch is the distance between the…?
centers of adjacent rivets in the same row.
Which fiber to resin (percent) ratio for advanced composite wet lay-ups is generally considered the best for strength?
60:40
Hole filling fasteners (for example, MS20470 rivets) should not be used in composite structures primarily because of the…?
Possibility of causing delamination
Sandwich panels made of metal honeycomb construction are used on modern aircraft because this type of construction…?
has high strength to weight ratio.
MS20426AD-6-5 indicates a countersunk rivet which has
an overall length of 5/16 inch.
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.
When straightening members made of 2024-T4, you should
straighten cold and reinforce
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.
Unless otherwise specified, the radius of a bend is the…?
inside radius of the metal being formed.
Shallow scratches in sheet metal may be repaired by…?
burnishing.
(Refer to Figure 5.) What is the length of flat A?
3.7 inches.
(Refer to Figure 3.) Which is the grip length of the flush rivet?
C. (3) - The grip length of a rivet is the total thickness of the material held together by the rivet. In this question, the grip length is dimension 3.
Alloy 2117 rivets are heat treated
by the manufacture and do not require heat treatment before being driven.
A DD rivet is heat treated before use to…?
soften to facilitate riveting.
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.
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.
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.
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.
Which of the following need not be considered when determining minimum rivet spacing?
Rivet length.
When an MS20470D rivet is installed, its full shear strength is obtained
only after a period of age hardening.
The classification for fiberglass reinforcement material that has high resistivity and is the most common is…?
E-glass
Mild steel rivets are used for riveting ____ ____?
Steel Parts
The primary alloying agent of 2024-T3 is indicated by the number __?
2
The primary alloying agent in 2024-T3 aluminum alloy is copper, which is identified by the first digit 2.
The sharpest bend that can be placed in a piece of metal without critically weakening the part is called the ___________________________?
minimum radius of bend.
Joggles in removed rivet shanks would indicate partial…?
shear failure.
(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
Statement (1) is true. A change in the sound made by the coin being tapped on a piece of composite structure may be caused by damage or by a transition to a different type of internal structure.
Statement (2) is not true. The ring, or coin tap, test is a quick and unscientific type of test that gives an indication of possible damage but does not accurately measure the extent of separation.
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.
Aircraft structural units, such as spars, engine supports, etc., which have been built up from sheet metal, are normally…?
repairable, using approved methods.
The installation of Cherrymax and Olympic-Lok rivets is accomplished by utilizing…?
a pulling tool.
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.
The most important factors needed to make a flat pattern layout are…?
radius, thickness, and degree of bend.
Which of these methods may be used to inspect fiberglass/honeycomb structures for entrapped water?
- Acoustic emission monitoring.
- X-ray.
- Backlighting.
2 and 3. (X-ray and Backlighting).
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.
How does acoustic emission testing detect defects in composite materials?
By picking up the “noise” of any deterioration that may be present.
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 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 general rule for finding the proper rivet diameter is…?
three times the thickness of thickest sheet.
Which part(s) of a semi-monocoque fuselage prevent(s) tension and compression from bending the fuselage?
Longerons and Stringers
A rivet set used to drive MS20470 rivets should…?
have a slightly greater radius than the rivet head.
A factor which determines the minimum space between rivets is the
diameter of the rivets being used.
The shop head of a rivet should be…?
one and one-half times the diameter of the rivet shank.
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
Longitudinal (fore and aft) structural members of a semi-monocoque fuselage are called ________ and ________?
Longerons and Stringers.
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
The coefficient of expansion of most plastic enclosure materials is…?
greater than both aluminum and steel.
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
Most rivets used in aircraft construction have…?
dimples
What should be the included angle of a twist drill for soft metals?
90°
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.
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.
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 is 0.125 inch, and the 1/8-inch rivets should extend through 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.
Cabin upholstery materials installed in current standard category airplanes must…?
be at least flame resistant.
The Dzus turnlock fastener consists of a stud, grommet, and receptacle. The stud length is measured in…?
hundredths of an inch
Which rivet is used for riveting magnesium alloy structures?
5056 Aluminum
To prevent corrosion in a magnesium structure, 5056 aluminum alloy rivets should be used. Magnesium is the chief alloying agent in 5056 aluminum alloy.
The purpose of a joggle is to…?
allow clearance for a sheet or an extrusion.
The preferred way to make permanent repairs on composites is by…?
laminating on new repair piles.
A main difference between Lockbolt/Huckbolt tension and shear fasteners (other than their application) is in the…?
number of locking collar grooves.
A category of plastic material that is capable of softening or flowing when reheated is described as a…?
thermoplastic.
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 at 90degree to the grain of the sheet.
The strength and stiffness of a properly constructed composite buildup depends primarily on…?
the orientation of the piles to the load direction
(Refer to Figure 4.) The amount of material required to make the 90° bend is…?
0.3436
(Refer to Figure 5.) What is the flat layout dimension?
6.8 inches
What type loads cause the most rivet failures?
Shear
Which is an identifying characteristic of acrylic plastics?
Zinc chloride will have no effect
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
On a sheet metal fitting layout with a single bend, allow for stretching by…?
subtracting the setback from both legs.
When inspecting a composite panel using the ring test/tapping method, a dull thud may indicate…?
separation of the laminates.
Under certain conditions, type A rivets are not used because of their…?
low strength characteristics.
(Refer to Figure 2.) 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.
A piece of flat stock that is to be bent to a closed angle of 15° must be bent through an angle of…?
165°
What is the most common method of cementing transparent plastics?
Soak method.
Which of the following, when added to wet resins, provide strength for the repair of damaged fastener holes in composite panels?
- Microballoons.
- Flox.
- Chopped fibers.
2 and 3 (Flox and Chopped fibers)
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-ketone)
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.
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.
The monocoque fuselage relies largely on the strength of…?
skin or covering.
The Dzus turnlock fastener consists of a stud, grommet, and receptacle. The stud diameter is measured in…?
sixteenths of an inch.
You can distinguish between aluminum and aluminum alloy by…?
testing with a 10 percent solution of caustic soda
(Refer to Figure 6.) What is dimension D?
Setback = .252
Bend allowance = .345
4.182 inches
The classification for high tensile strength fiberglass used in aircraft structures is…?
S-glass.
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.
How many of the following are benefits of using microballoons when making repairs to laminated honeycomb panels?
- Greater concentrations of resin in edges and corners.
- Improved strength to weight ratio.
- Less density
- Lower stress concentrations
2, 3, and 4
Phenolic microballoons are used to improve the strength-to-weight ratio of a repair, to decrease the density of the repair, and to give greater flexibility, thus lowering the stress concentrations in the repair area.
Reference: AC 43.13-1B
Fiberglass laminate damage that extends completely through one facing and into the core…?
requires the replacement of the damaged core and facing.
A potted compound repair on honeycomb can usually be made on damages less than…?
1 inch in diameter.
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 carbon/graphite fiber composites?
- Flexibility.
- Stiffness.
- High compressive strength.
- Corrosive effect in contact with aluminum.
- Ability to conduct electricity.
2, 3, and 4.
The length of time that a catalyzed resin will remain in a workable state is called the…?
pot life.
Which rivet is used for riveting nickel-steel alloys?
Monel
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 the purpose of refrigerating 2017 and 2024 aluminum alloy rivets after heat treatment?
To retard age hardening.
Metal fasteners used with carbon/graphite composite structures
must be constructed of material such as titanium or corrosion resistant steel.
One of the main advantages of Hi-Lok type fasteners over earlier generations is that…?
they can be installed with ordinary hand tools.
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.
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
(Refer to Figure 4.) The length of flat A is…?
Flat A is 4 inches and Flat B is 3 inches and the radius is 3/16
3.750 inches.
When drilling stainless steel, the drill used should have an included angle of…?
140° and turn at low speed.
Which of the following drill bit types work best when drilling an aramid fiber (Kevlar(c)) composite laminate?
Carbide W-Point.
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 (1/2 inch) long.
Clad aluminum alloys are used in aircraft because they…?
are less subject to corrosion than uncoated aluminum alloys.
What reference tool is used to determine how the fiber is to be oriented for a particular ply of fabric?
Warp clock (or compass).
(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
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
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
Threaded rivets (Rivnuts) are commonly used to…?
Attach parts or components with screws to sheet metal.
Which rivet may be used as received without further treatment?
2117-T3.
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.
Fiberglass damage that extends completely through a laminated sandwich structure…?
May be repaired.
(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
Repairing advanced composites using materials and techniques traditionally used for fiberglass repairs is likely to result in…?
An unworthy repair.
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.
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 should be the included angle of a twist drill for hard metal?
118°
The identifying marks on the heads of aluminum alloy rivets indicate the…?
specific alloy used in the manufacture of the rivet.
What is the material layer used within the vacuum bag pressure system to absorb excess resin during curing called?
Bleeder
Fiberglass laminate damage not exceeding the first layer or ply can be repaired by…?
filling it with a putty consisting of a compatible resin and clean, short glass fibers.
