Lecture 13 Flashcards
What is an aluminum alloy?
A chemical composition where other elements are added to pure aluminum in order to enhance its properties
Primarily to increase its strength
What does 2024 mean when talking about aluminum alloys?
Copper can be found in the aluminum alloy
Sort T3, T351, and T4 from strongest temper to weakest temper
T351
T4
T3
What are some elements that can be added to aluminum?
How much of the weight of the alloy do these additions make up?
Iron, silicon, copper, magnesium, manganese and zinc
15% of the alloy by weight
How is AlClad aluminum created?
Cladding (covering) a aluminum alloy inner core with surface layers of pure aluminum
Pure aluminum for corrosion resistance
Produced by rolling
How much of AlClad aluminum is pure aluminum?
5.5% thickness per side
A metal’s strength is directly related to its _____ and _____, and _____.
grain size
orientation
heat treatment (temper)
How does the grain in sheet metal align itself?
The grains align themselves parallel with the rolling operation when the metal is rolled out to form a sheet
What is a composite material?
A material which is produced from two or more materials
In a typical jet today, how much of it is pure aluminum?
As little as 20%
A _____ sheet is a requirement via _____ and other workplace organizations for any workplace to provide to its _____.
Safety data sheet (SDS)
OSHA
employees
What is AC 43.13 1B?
Advisory circular (AC)
Contains methods, techniques, and practices “acceptable” for the inspection and repair of of civil aircraft
Only to be used when there are no manufacturer repair or maintenance instructions**
Sheet metal that is used for structure and outer aircraft covering is made from _____ and _____.
aluminum alloys
composites
How are parts of sheet metal formed and joined?
Rivets or other types of fasteners
What are the different types of specification to which aircraft hardware adheres to?
National Aerospace Standard (NAS)
Amy-Navy (AN)
Military Standard (MS)
What are the five different load types?
Compression (push together)
Tension (pull apart)
Shear (top pulls left, bottom pulls right)
Torsion (top and bottom spin in opposite directions)
Bending (pressure placed on middle)
What is the preferred construction method for metal aircraft?
Why?
Solid shank rivets
They fill up the hole, which results in good load transfer
What is yield strength?
Working load limit
The amount of stress a material can withstand without permanent deformation
What is tensile strength?
The maximum amount of axial stress that a material can take before breaking
How is the size and type of rivet to be used determined?
Loads imposed on the structure
Applications the parts will be in
Alloy of the material to be joined
Manufacturer
Information found in the manufacturer’s Structural Repair Manual (SRM)
Information in the advisory circular (AC) is _____ data NOT _____ data.*
acceptable
approved
How are drill bits sized?
What tool is used to size a drill bit?
Fractions, numbers, and letters
Drill gages
Aviation uses _____ drill bits for installing rivets
numbered
Larger drill bits are denoted by _____ numbers.
Smaller drill bits are denoted by _____ numbers.
smaller
larger
Drill bits are selected based on the _____.
rivet shank diameter
What is the process for drilling a hole?
Drill with a hand drill held perpendicular to the work
Apply medium pressure to prevent walks
Use a center punch to aid in drilling accurately
After drilling a hole, the material must be _____ on both sides.
deburred
What tools are used for countersinking?
Microstop countersink tool
Dimpler dies
What type of metal can you not countersink?
Thin sheetmetal
Aviation rivets have a _____ countersunk head.
100°
When would a dimpler die be used?
When sheet metal is .032” or less when using an 1/8” rivet
What is de-burring?
To remove the rough edges of a hole or sheet after it has been drilled or cut
Why is de-burring important?
Removes stress risers that cause incorrect riveting and stress cracking
What are clecos?
Hold sheet metal together in preparation for fasteners
What are some common types of rivet installers?
Hand squeezers
Pneumatic air gun and bucking bar
Pneumatic squeezers
What is considered the oldest and most reliable fastener?
When was it first used?
Solid rivets
During the bronze age
What is the most common type of solid rivet?
Universal head (rounded)
100 ̊ countersunk heads (flat heads)
How is a solid rivet installed?
Driving (squeezing) the body with pneumatic or hand tools
What are solid rivets made of?
A variety of aluminum alloys and specialty metals
What are bolts?
Threaded fasteners used to assemble components, structures and assemblies
For aircraft, what are bolts often made of?
Why?
Stainless steel or cadmium plated
Corrosion resistance
What is a “grip” length?
How is grip determined?
The unthreaded section on the shank of a bolt
The grip should be equal to the thicknesses of the two pieces being held together
What is different about aircraft bolts?
Drilled heads or drilled shanks for safety devices
How are threads measured?
What are the two types of threads?
TPI gage (threads pre-inch)
Fine (UNF) or coarse (UNC)
How do you identify bolts?
Different marks on the head of the bolt that denote alloy type, strength, and application
What are the parts of a bolt?
Head
Shank
Grip
Threads
How is bolt or screw length measured?
The bottom of the head to the end of the shank/threads
What are nuts used for?
Secure bolts & screws in assemblies
Made for shear and tension applications
Can nuts be drilled for safety wire?
Yes
What is the purpose of aircraft washers?
Spread the load of a fastener
Protect the metal from galling
How are aircraft washers sized?
The inside diameter and thickness
How are aircraft washers different from automobile washers?
They cannot be interchanged
What is torque?
A measure of how much a force acting on an object causes that object to rotate
Measured in inch pounds or foot pounds
12 in.lbs.= 1 ft.lb.
What are the three types of torque wrenches?
Click type
Dial type
Beam type
When would the torque wrench formula be used?
Why?
When an attachment (extension) is used which effectively changes the length of the wrench
The formula compensates for the additional length
Bolts and fasteners are torqued (tightened) according to _____.
size
Where are torque values found?
In torque charts
When possible, where is torque applied?*
To the nut
What is safety wire used to secure?
Anything that has the potential to loosen during normal operations
Nuts
Bolts
Oil filters
Cannon plugs
How is safety wire twisted?
By hand or with duckbill pliers
Most often with safety wire pliers
What safety wire pattern is used to prevent things from loosening?
S or Z pattern
What are cotter pins used for?
What are they used in combination with to prevent spinning?
Secure bolts, screws, nuts and pins
Castle nut
What are Hi-Lok Fasteners?
Simple two-part, structural fastener designed to achieve consistent torque on each fastener
What happens when tightening a Hi-Lok fastener?
The fastener gets tightened onto the bolt until required torque amount and end piece breaks/shears off
What is a blind fastener?
What is the process of inserting a blind rivet?
Used once the original solid fastener was removed and you only have access to one side of the fastener
Inserted into rivet hole, center piece is pulled out, crushing the end of the rivet against the surface until required torque is reached and the center piece shears off
What is welding?
Joins metals by melting the work pieces (or a separate rod of material) until they are united together
When was welding first used?
How has the process evolved?
The Bronze age, but modern welding developed in the 19th century
Lighter metals like aluminum, magnesium and titanium*
What are the four types of welding?
Gas or oxy/act welding
TIG welding
MIG welding
Electric arc welding
What is gas welding?
How is a gas weld done?
Fusion process in which heat is supplied by burning a mixture of oxygen and gas such as acetylene (oxyacetylene)
Done by heating the ends or edges of metal parts to a molten state with a high temperature flame
How is a GMAW (MIG) weld done?
A spool of wire constantly moves through the gun then melts to form the weld
Argon, helium or carbon dioxide is used as the inert gas (not going to catch fire or poison you)
Shielding gas dispersed by gun shields weld from air to prevent oxidation
What is a GTAW (TIG) weld?
How is a GTAW (TIG) weld done?
What materials does this type join together?
Weld produced by an electric arc (power supply)
Foot pedal starts the arc and the gas
Long rods to fuse two metals directly together
Gas shields the electrode to prevent contamination
Electrode doesn’t touch the work
Welds aluminum, copper, stainless, magnesium and titanium
What is brazing?
What materials does brazing join together?
Filler metal is deposited in the joint other than by capillary attraction
Copper, bronze, nickel and other non-ferrous metals to stainless steel
What is soldering?
What must be in place before soldering?
A relatively weak joint made by melting wire over a section
Must have flux to work properly (removes films on the surface being soldered)
Flux can be in the solder or in a separate container
