Sheet Metal and Non-Metallic Structures Flashcards
A well-designed rivet joint will subject the rivets to what?
shear loads.
A main difference between Lockbolt/Huckbolt tension and shear fasteners (other than their application) is the what?
number of locking collar grooves.
Alloy 2117 rivets are heat treated how?
by the manufacturer and do not require heat treatment before being driven.
The general rule for finding the proper rivet diameter is what?
three times the thickness of the thickest sheet.
The shop head of a rivet should be what?
one and one-half times the diameter of the rivet shank.
One of the main advantages of HI-LOK type fasteners over earlier generations is that what?
they can be installed with ordinary hand tools.
Which of the following is one advantage of HI-LOK fasteners?
Inability to be over-torqued.
The markings on the head of a Dzus fastener identify the what?
body diameter, type of head, and length of the fastener.
The Dzus turnlock fastener consists of a stud, grommet, and receptacle. The stud length is measured in what?
hundredths of an inch.
The Dzus turnlock fastener consists of a stud, grommet, and receptacle. The stud diameter is measured in what?
sixteenths of an inch.
Threaded rivets (rivnuts) are commonly used to what?
attach parts or components with screws to sheet metal.
The installation of CherryMAX and Olympic-Lok rivets is accomplished by utilizing what?
a pulling tool.
Hole filling fasteners (for example, MS20470 rivets) should not be used in composite structures primarily because of the what?
possibility of causing delamination.
Metal fasteners used with carbon/graphite composite structures…
must be constructed of material such as titanium or corrosion resistant steel.
Sandwich panels made of honeycomb construction are used on aircraft because this type of construction…
saves weight while not comprising strength.
Which of these methods may be used to inspect fiberglass/honeycomb structures for entrapped water?
X-ray and backlighting.
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.
When repairing puncture-type damage to a metal-faced laminated honeycomb panel, the edges of the doubler should be tapered to…
100 times the thickness of the metal.
One of the best ways to assure that a properly prepared batch of matrix resin has been achieved is to what?
have mixed enough for a test sample.
How does acoustic emission testing detect defects in composite materials?
By picking up the “noise” of any deterioration that may be present.
When conducting a tap test on a composite panel, which of the following sounds would indicate delamination?
Dull thud.
What precaution, if any, should be taken to prevent corrosion inside a repaired metal honeycomb structure?
Paint the repair with a corrosion inhibitor and seal from the atmosphere.
One method of inspecting a laminated fiberglass structure that has been subjected to damage is to what?
strip the damaged area of all paint and shine a strong light through the structure.
When inspecting a composite panel using the ring test/tapping method, a dull thud may indicate what?
separation of the laminates.
Which of the following are benefits of using microballoons when making repairs to laminated honeycomb panels?
Improved strength-to-weight ratio, less density, and lower stress concentrations.
The length of time that a catalyzed resin will remain in a workable state is called the what?
pot life.
A category of plastic material that is capable of softening or flowing when reheated is described as a what?
thermoplastic
The classification of high tensile strength fiber-glass used in aircraft structures is what?
S-glass.
Which is an identifying characteristic of acrylic plastics?
Zinc chloride will have no effect.
Superficial scars, scratches, surface abrasion, or rain erosion on fiberglass laminates can generally be repaired by applying what?
One or more coats of suitable resin (room-temperature catalyzed) to the surface.
The classification for fiberglass reinforcement material that has high resistivity and is the most common is what?
E-glass.
A potted compound repair on honeycomb can usually be made on damages less than what?
1 inch in diameter.
Composite fabric material is considered to be the strongest in what direction?
Warp.
What reference tool is used to determine how the fiber is to be oriented for a particular ply of fabric?
Warp clock (or compass)
The strength and stiffness of a properly constructed composite buildup depends primarily on what?
the orientation of the plies to the load direction.
Which fiber to resin (percent) ratio for advanced composite wet lay-ups is generally considered the best for strength?
60:40
What is the material layer used within the vacuum bag pressure system to absorb excess resin during curing called?
Bleeder.
Proper prepeg (preimpregnated materials) composite lay-up curing is generally accomplished by what?
applying external heat and pressure.
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 what?
use short strips of fiberglass in the bonded repair.
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 what?
MEK (methyl ethyl ketone)
When necessary, what type of cutting fluid is usually acceptable for machining composite laminates?
Water only.
Fiberglass laminate damage not exceeding the first layer or ply can be repaired by what?
filling with a putty consisting of a compatible resin and clean, short glass fibers.
Fiberglass damage that extends completely through a laminated sandwich structure…
may be repaired.
Fiberglass laminate damage that extends completely through one facing and into the core…
requires the replacement of the damaged core and facing.
Repairing advanced composites using materials and techniques traditionally used for fiberglass repairs is likely to result in what?
an unairworthy repair.
The preferred way to make permenant repairs on composites is by what?
laminating on new repair plies.
Which of the following, when added to wet resins, provide strength for the repair of damaged fastener holes in composite panels?
Flox and chopped fibers.
The part of a replacement honeycomb core that must line up with the adjacent original is the what?
ribbon direction.
Which of the following are generally characteristic of aramid fiber (Kevlar) composites?
High tensile strength and flexibility.
Which of the following are generally characteristic of carbon/graphite fiber composites?
Stiffness, high compressive strength, and corrosive effect in contact with aluminum.
If an aircraft’s transparent plastic enclosure exhibit fine cracks which may extend in a network over or under the surface or through the plastic, the plastic is said to be what?
crazing, baby.
When installing transparent plastic enclosures which are retained by bolts extending through the plastic material and self-locking nuts, the nuts should be what?
tightened to a firm fit, then backed off one full turn.
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.
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.
The coefficient of expansion of most plastic enclosure materials is what?
greater than both steel and aluminum.
If no scratches are visible after transparent plastic enclosure materials have been cleaned, their surfaces should be what?
covered with a thin coat of wax.
Cabin upholstery materials installed in current standard category planes must what?
be at least flame resistant.
What is the most common method of cementing transparent plastics?
Soak method.
What type of bit should be used to drill holes in plexiglas?
a specially modified twist drill.
Which of the following drill bit types work best when drilling an aramid fiber (Kevlar) composite laminate?
Carbide W-point.
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.
Select the alternative which best describes the function of the flute section of a twist drill.
Forms the cutting edges of the drill point.
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.
On a semi-monocoque fuselage, the skin is reinforced by longitudinal structural members called what?
longerons and stringers.
Shallow scratches in sheet metal may be repaired by what?
burnishing.
What should be the included angle of a twist for soft metals?
90 degrees.
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 what?
Lower speed with more pressure applied to the drill.
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 what?
13/16 inch.
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.
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.
What is the minimum edge distance for aircraft rivets?
Two times the diameter of the rivet shank.
When drilling stainless steel, the drill used should have included angle of what?
140 degrees and turn at a low speed.
What is the minimum spacing for a single row of aircraft rivets?
Three times the diameter of the rivet shank.
(Refer to figure 1) Which of the rivets shown will accurately fit the conical depression made by a 100 degree countersink?
1.
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.
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.
When repairing a small hole on a metal stressed skin, the major consideration in the design of the patch should be what?
The sheer strength of the riveted joint.
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.
Repairs of splices involving stringers on the lower surface of stressed skin metal wings are usually what?
permitted but are normally more critical in reference to strength in tension than similar repairs to the upper surface.
When straightening members made of 2024-T4, you should what?
straighten cold and reinforce.
Clad aluminum alloys are used in aircraft because they what?
have surface layers of pure aluminum or aluminum alloy bonded to the core material to inhibit corrosion.
Which statement is true regarding a cantilever wing?
No external bracing is needed.
Aircraft structural units, such as spars, engine supports, etc., which have been built up from sheet metal, are normally what?
repairable, using approved methods.
A factor which determines the minimum space between rivets is the what?
diameter of the rivets being used.
What should be the included angle of a twist drill for hard metal?
118 degrees.
Parts fabricated from Alclad 2024-T3 aluminum sheet stock must have all what?
scratches, kinks, tool marks, nicks, etc., held to a minimum.
The monocoque fuselage relies largely on the strength of what?
skin or covering.
Which parts of a semi-monocoque fuselage prevent tension and compression from bending the fuselage?
Longerons and stringers.
Rivet gauge, or transverse pitch is the distance between the what?
centers of rivets in adjacent rows.
Rivet pitch is the distance between the what?
centers of adjacent rivets in the same row.
(Refer to Figure 2.) Select the preferred drawing for proper countersinking.
1.
What is the indicated by black “smoky” residue streaming back from some of the rivets on an aircraft?
Fretting corrosion is occurring between the rivets and the skin
The identifying marks on the heads of aluminum alloy rivets indicate the what?
specific alloy used in the manufacture of the rivets.
When an MS20470D rivet is installed, its full shear strength is obtained…
only after a period of age hardening.
Which of the following need not be considered when determining minimum rivet spacing?
Rivet length.
What is the purpose of refrigerating 2017 and 2024 aluminum alloy rivets after heat treatment?
To retard age hardening.
Under certain conditions, type a rivets are not used because of their what?
low strength characteristics.
A rivet set used to drive MS20470 rivets should what?
have a slightly greater radius than the rivet head.
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 dimensions of an MS20430AD-4-8 rivet are what?
1/8 inch in diameter and 1/2 inch long.
The primary alloying agent of 2024-T3 is indicated by the number what?
2
Which part of 2017-T36 aluminum alloy indicates the temper designation?
T36.
Which part of the 2017-T36 aluminum alloy designation indicates the primary alloying agent used in its manufacture?
2.
A sheet metal repair is to be made using two pieces of 0.040-inch aluminum riveted together. All holes are drilled for 3/32-inch rivets. The length of the rivets to be used will be what?
1/4 inch.
Most rivets used in aircraft construction have what?
dimples.
MS20426AD-6-5 indicates a countersink rivet which has what?
an overall length of 5/16 inch.
Which rivet may be used as recieved without further treatment?
2117-T3.
(Refer to Figure 3.) Which is the grip length of the flush rivet?
3
Which rivets should be selected to join two sheets of .032-inch aluminum?
MS20470AD-4-4
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 what?
5/16 inch.
Mild steel rivets are used for riveting what?
steel parts.
A DD rivet is heat treated before use to what?
soften to facilitate riveting.
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.
The length of a rivet to be used to join a sheet of .032-inch and .064-inch aluminum alloy should be equal to what?
one and one-half times the rivet diameter plus .096 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.
Joggles in removed shanks would indicate partial what?
shear failure.
What type loads cause the most rivet failures?
Shear.
Which rivet is used for riveting magnesium alloy structures?
5056 aluminum.
Which rivet is used for riveting nickel-steel alloys?
Monel.
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 what?
5/16 inch.
(Refer to Figure 4.) The length of flat A is what?
3.750 inches.
(Refer to Figure 4.) The amount of material required to make the 90 degree bend is what?
0.3436 inch.
(Refer to Figure 5.) What is the length of flat A?
3.7 inches.
(Refer to Figure 5) What is the flat layout dimension?
6.8 inches.
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 what?
started by tapping the aluminum lightly around the edges and gradually working down into the center.
A piece of flat stock that is to be bent to a closed angle of 15 degrees must be bent through an angle of what?
165 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 flat layout of 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 what?
1/8 inch.
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 what?
found by adding approximately one-half of the stock thickness to the bend radius.
Unless otherwise specified, the radius of a bend is the what?
inside radius of the metal being formed.
The sharpest bend that can be placed in a piece of metal without critically weakening the part is called the what?
minimum radius of bend.
The most important factors needed to make a flat pattern layout are what?
radius, thickness, and degree of bend.
A piece of sheet metal is bent to a certain radius. The curvature of the bend is referred to as the what?
bend radius.
You can distinguish between aluminum and aluminum alloy by what?
testing with a 10 percent solution of caustic soda.
The purpose of a joggle is to what?
wiggle woggle.
and allow clearance for a sheet or an extrusion.
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 what?
neutral line.
(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
(Refer to Figure 6) What is dimension D?
Setback = .252
Bend Allowance = .345
4.182
The slight 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.
(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
On a sheet metal fitting layout with a single bend, allow for stretching by what?
subtracting the setback from both legs.
The aluminum alloys used in aircraft construction are usually hardened by which method?
Heat treatment.
