Sheet Metal and Non Metallic Structures Flashcards
A well-designed rivet joint will subject the rivets to
Shear loads
A main difference between Lockbolt/Huckbolt tension and shear fasteners (other than their application)
is in the
Number of locking collar grooves
Alloy 2117 rivets are heat treated
By the manufacturer and do not require heat treatment before being driven
The general rule for finding the proper rivet diameter is
Three times the thickness of the thickest sheet
The shop head of a rivet should be
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
They can be installed with ordinary hand tools
The markings on the head of a Dzus fastener identify the
Body diameter ,type of head, and length of the fastener
The markings on the head of a Dzus fastener identify the
Body diameter ,type of head, and length of the fastener
The Dzus turnlock fastener consists of a stud, grommet, and receptacle. The stud diameter is measured in
Sixteenths of an inch
Threaded rivets (Rivnuts) are commonly used to
Attach parts or components with screws to sheet metal
The installation of Cherrymax and Olympic-Lok rivets is accomplished by utilizing
a pulling tool
Hole filling fasteners (for example, MS20470 rivets) should not be used in composite structures primarily
because of the
Possibility of causing delamination
Metal fasteners used with carbon/graphite composite structures
Must constructed of material such as titanium or corrosion resistant steel
Sandwich panels made of metal honeycomb construction are used on modern aircraft because this type
of construction
Has a high strength to weight ratio
(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
Which of these methods may be used to inspect fiberglass/honeycomb structures for entrapped water?
1. Acoustic emission monitoring.
2. X-ray.
3. Backlighting.
2 and 3
When balsa wood is used to replace a damaged honeycomb core, the plug should be cut so that
Grain is perpendicular to the skin
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
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
Composite inspections conducted by means of acoustic emission monitoring
By Picking up the ‘noise’ of any deterioration that may be present
What precaution, if any, should be taken to prevent corrosion inside a repaired metal honeycomb
structure?
Prime the repair with corrosion inhibitor and seal from the atmosphere
One method of inspecting a laminated fiberglass structure that has been subjected to damage is to
Strip the damage 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
Separation of the laminate
How many of the following are benefits of using microballoons when making repairs to laminated
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
The length of time that a catalyzed resin will remain in a workable state is called the
Pot life
A category of plastic material that is capable of softening or flowing when reheated is described as a
Thermoplastic
The classification for high tensile strength fiberglass used in aircraft structures is
S - glass
Which is an identifying characteristic of acrylic plastics?
Zinc chloride with no effect
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
The classification for fiberglass reinforcement material that has high resistivity and is the most common
is
E - glass
A potted compound repair on honeycomb can usually be made on damages less than
1 inch in diameter
Composite fabric material is considered to be the strongest in what direction?
Warp
hat reference tool is used to determine how the fiber is to be oriented for a particular ply of fabric?
Warp clock (compass)
The strength and stiffness of a properly constructed composite buildup depends primarily on
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 pre-preg composite lay-up curing is generally accomplished by
1. applying external heat.
2. room temperature exposure.
3. adding a catalyst or curing
4. applying pressure.
1 and 4
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 strip 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
MEK (methyl ethyl ketone)
When necessary, what type of cutting fluid is usually acceptable for machining composite laminates?
Water only
Fiberglass damage that extends completely through a laminated sandwich structure
Maybe 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
An unairworthy repair
The preferred way to make permanent repairs on composites is by
Laminating an new repair plies
Which of the following, when added to wet resins, provide strength for the repair of damaged fastener
holes in composite panels?
1. Microballoons.
2. Flox.
3. Chopped fibers.
2 and 3
The part of a replacement honeycomb core that must line up with the adjacent original is the
Ribbon direction
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 of the following are generally characteristic of carbon/graphite fiber composites?
1. Flexibility.
2. Stiffness.
3. High compressive strength.
4. Corrosive effect in contact with aluminum.
5. Ability to conduct electricity.
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 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
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
Greater than both steel and aluminum
If no scratches are visible after transparent plastic enclosure materials have been cleaned, their surfaces
should be
Covered with a thin coat of wax
Cabin upholstery materials installed in current standard category airplanes must
be at least flame resistant
What is the most common method of cementing transparent plastics?
Soaked method
When holes are drilled completely through Plexiglas, a
Specially modified twist drill should be used
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.
Form the cutting edges of the drill point
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
Longerons and stringers
Shallow scratches in sheet metal may be repaired by
Burnishing
What should be the included angle of a twist drill for soft metals?
90’
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
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
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 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 an included angle of
140 degrees and turn at 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°
countersink?
1
Which is correct concerning the use of a file?
Apply the pressure on the forward stroke only, except when filing very soft metals such as
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
The shear 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 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
When straightening members made of 2024-T4, you should
Straighten cold and reinforce
Clad aluminum alloys are used in aircraft because the
Are less subjected to corrosion than uncoated aluminum alloys
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
Repairable using approve method
A factor which determines the minimum space between rivets is the
Diameter of rivets being used
What should be the included angle of a twist drill for hard metal?
118 degrees
When fabricating parts from Alclad 2024-T3 aluminum sheet stock,
All scratches, kinks tool marks,nick, etc., must be held to a minimum
The monocoque fuselage relies largely on the strength of
skin or covering
Which part(s) of a semi-monocoque fuselage prevent(s) tension and compression from bending the
fuselage?
Longerons and stringers
Rivet gauge, or transverse pitch is the distance between the
Centers of rivets in adjacent rows
Rivet pitch is the distance between the
Centers of adjacent rivets in the same row
(Refer to Figure 2.) Select the preferred drawing for proper countersinking.
1
What is indicated by a black ‘smoky’ residue streaming back from some of the rivets on an aircraft?
Fretting corrosion occurring between the rivets and the skin
The identifying marks on the heads of aluminum alloy rivets indicate the
Specific alloy used in the manufacture of 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?
Revit 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
Low strength characteristics
A rivet set used to drive MS20470 rivets should
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
1/8 inch in diameter and 1/2 inch long
The primary alloying agent of 2024-T36 is indicated by the number
2
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 rivet
holes are drilled for 3/32-inch rivets. The length of the rivets to be used will be
¼ inch
Most rivets used in aircraft construction have
Dimples
MS20426AD-6-5 indicates a countersunk rivet which has
An overall length of 5/16 inch
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?
2
Which rivets should be selected to join two sheets of .032-inch aluminum?
MS2047AD-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
5/16 inch
Mild steel rivets are used for riveting
Steel parts
A DD rivet is heat treated before use to
Soften to facilitate riveting
When riveting dissimilar metals together, what precautions must be taken to prevent an electrolytic
action?
Place protective separator between the 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
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 rivet shanks would indicate partial
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
5/16
(Refer to Figure 4.) The length of flat A is
3.750 inches
(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
Started by tapping 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° must be bent through an angle of
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 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
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
Unless otherwise specified, the radius of a bend is the
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
Minimum radius of bend
The most important factors needed to make a flat pattern layout are
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
Bend radius
You can distinguish between aluminum and aluminum alloy by
Testing with a 10 percent solution of caustic soda
The purpose of a joggle is to
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
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 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
(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
Subtracting the setback from both legs
