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 is in the
number of locking collar grooves
Alloy 2117 rivets are heat treated
by the manufacture and do not require heat treatment before being driven
The general rule for finding the proper rivet diameter
three times the thickness of the thickest sheet
The shop head of a rivet should be
one and a 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
Which of the following is on advantage of Hi-Lok fasteners?
Inability to be over torqued
The markings on the head of a Dzus fastener identify the
body diameter, type of head and length of fastener
The Dzus turnlock fastener consists of a stud, grommet and receptacle. The stud length is measured in
Hundredths of a inch
The Dzus turnlock fastener consists of a stud, grommet and receptacle. The stud diameter is measured in
Sixteenths of a inch
Threaded rivets (Rivnuts) are commonly used to
attach parts or components with screws to sheet metal
The installation of Cherry-max 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 be constructed of material such as titanium or corrosion resistant steel
Sandwich panels made of metal honeycomb construction are used in high speed on aircraft because this type of construction
saves weight while not compromising on strength
No.1 When performing a ring tap (coin tap) test on composite structures, a change in sound may be due to damage or to transition to a different internal structure
No.1 is only true
Which of these methods may be used to inspect fibreglass/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 in perpendicular to the skin
When preparing a wood surface for bonding, what should NOT be used?
Sandpaper
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 of 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 honeycomb structure?
Prime the repair with a corrosion inhibitor and seal from atmosphere
One method of inspecting a laminated fibreglass structure that has been subjected to damage is to
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
seperation of the laminates
Which of the following are benefits of using micro balloons 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
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 fibreglass used in aircraft structure is
S-glass
Which is a identifying characteristic of acrylic plastics?
Zinc chloride will have no effect
Superficial scars, scratches surface abrasion or rain erosion on fibreglass laminates can generally be repaired by applying
one or more coats of suitable resin (room temp catalyzed) to the surface
The classification for fibreglass reinforcement material that has high resistivity and is the most common in
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
What reference tool is used to determine how the fibre is to be oriented for a particular ply of fabric?
Warp clock
The strength and stiffness of a properly constructed composite buildup depends on primarily on
the orientation of the plies to the load direction
Which fibre 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 prepreg composite lay-up curing is generally accomplished by
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
use short strips of fibreglass in the bonded repair
When making repairs to the fibreglass, cleaning of the area is essential for a good bond. The final cleaning should be made with
MEK (methyl ethyl ketone)
When necessary, what type of cutting fluid is usually acceptable for machining composite laminates?
Water only
Fibreglass 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 fibres
Fibreglass damage that extends completely through a laminated sandwich structure
may be repaired
Repairing advanced composites using materials and techniques traditionally used for fibreglass repairs is likely to result in
an unairworthy repair
The preferred way to make permanent repairs on composites is by
laminating on new repair plies
Which of the following, when added to wet resin, provide strength for the repair of damaged fastener holes in composite panels?
flox and chopped fibres
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 characteristics of aramid fibre (Kevlar) composite?
High tensile strength and flexibility
Which of the following are generally characteristic of carbon/graphite fibre composite?
Stiffness, high compressive strength and the corrosive effect in contact with aluminium
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 to be 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 material installed in current standard category airplanes must
be at least flame resistant
Which regulation provides the airworthiness standards for an airplane certificated in the normal category?
14 CFR Part 23
What is the most common method of cementing transparent plastics?
soak method
What type of bit should be used to drill holes in plexiglass?
a specially modified twist drill
Which of the following drill bit types work best when drilling an aramid fibre (Kevlar) composite laminate?
Carbide W-Point or Tapered carbide point
What is the purpose of a 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, min edge distance and 4D spacing?
56
On a semi-monocoque fuselage, the skin is reinforced by longitudinal structural members called
longerons and stringers
Shallow scratches in sheet metal may be repaired by
burnishing
Which maintenance action is an airframe major repair?
The repair of portions of skin sheets by making additional seams
What should be the included angle of a twist drill for soft metals?
90 degrees
When comapring the machining techniques for stainless steel sheet material to those for aluminium 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 aluminium skin. If a double row of 1/8 inch rivets is used, the min allowable overlap will be
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 join 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 an included angle of
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
What 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 aluminium
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 one of the determining factors that requires the use of dimpling instead of countersinking?
Thickness of the material is less 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 aluminium alloys are used in aircraft because they
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 from sheet metal are normally
repairable using approved methods
A factor which determines the minimum space between rivets is
diameter of the rivets being used
What should be the included angle of a twist drill for hard metal?
118 degrees
When fabricated parts from Alclad 2024-T3 aluminium sheet stock, all
scratches, kink, tool marks, nicks etc must be held to a minimum
Monocoque fuselage relies largely on the strength of
skin or coverings
Which part of a semi monocoqoue fuselage prevents tension and compression from bending the fuselage?
Longerons and stringers
Rivet gauge or transverse pitch is the distance between
centre of rivets in adjacent rows
Rivet pitch is the distance between the
centre of adjacent rivets in the same row
What is indicated by a black ‘smoky’ residue streaming back from some of the rivets on an aircraft?
Fretting corrosion is occuring between the rivets and the skin
The identifying marks on the heads of aluminium alloy rivets indicate the
specific alloy used in 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
Rivets can be stored below 32 degrees for how long after heat treatment to retard hardening?
24 hours
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 with in the prescribed time after heat treatment or removal from refrigeration
must be reheat treated before use
The dimension of an MS20430AD-4-8 are
1/8 inch in diameter and 1/2 inch long
The primary alloying agent of 2024-T36 is indicated by the number
2 (First number)
Which part of 2024-T3 indicated the temper designation?
T3
Which part of 2017-T36 aluminum alloy designation indicates the primarily alloying agent used in it 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 rivets. The length of the rivets to be used will be
1/4 inch
Most rivets used in aircraft construction have
dimples
MS20426AD-6-5 indicated a counter sink rivet which has
an overall length of 5/16 inch
Which rivet may be used as received without further treatment?
2117-T3
Which rivet 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
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 a protective separator between areas of potential electrical difference
The length of a rivet to be used to join a sheet of 0.032-inch and .064-inch aluminium alloy should be equal to
one and 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 head one size smaller than the rivet shank and remove the rivet with a punch
Joggles in removed rivet shank would indicate partial
shear failure
Joggles in rivet shanks due to shear failure would get replaced by which of the following?
A larger solid replacement rivet
What types of loads cause the most rivet failures?
Shear
Which rivet is used for riveting magnesium alloy structure?
5056 aluminium
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 a 0.032-inch and 0.064-inch aluminum sheet, drilled with a No. 30 drill, is
5/16 inch
If a streamline cover plate is to be hand formed by 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 centre
A piece of flat stock that is to be bent to closed angle of 15 degrees must be bent through an angle of
165 degrees
When a piece of aluminum alloy is to be bent using a minimum bend 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 table 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
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 extrusion
When bending metal, the material on the outside of the curve stretches while the material on the inside if the curve compresses. That part of the material which is not affected by either stress is the
neutral line
The sight line on a sheet metal flat layout to be bent is measured and marked
one radius from the bend tangent line that is placed under the brake
On a sheet metal fitting layout with a single bend allow for stretching
by subtracting the setback from both legs
The aluminum alloys used in aircraft construction are usually hardened by which method?
heat treatment
