aircraft material, hardware, and process Flashcards
what is the alloy number of the most commonly used aluminum alloy for aircraft structural use
2024-T
what is the alloy number of a high strength aluminum ally that has zinc as an alloying compnent
7075
what type of composite material is used when stiffness is the prime requirement
graphite (carbon)
what type of composite material is used when toughness is the prime requirement
kevlar
why is a piece of steel tempered after it has been hardened
when steel is hardened it becomes brittle. tempering removes some of its brittleness
how is steel annealed
it is heated to just above its upper critical temp until it reached a uniform temp throughout, then it is cooled very slowly in the oven
how it steel hardened
it is heat to its critical temperature and then quenched in water, brine, or oil
what is meant by tempering steel
steel is first hardened; then some of the hardness is removed to relieve some of the internal stresses and brittleness
what is meant by case hardening
the surface of the metal is hardened by the infusion of carbon or aluminum nitride. the interior of the metal remains strong and tough
what are two methods of case hardening
carburizing and nitrating
how its steel nitrided
steel part is heated in a retort in which there is an atmosphere of ammonia (compound of nitrogen and hydrogen). Aluminum, an alloying element in the steel, combines with the nitrogen to form an extremely hard aluminum nitride on the surface of the steel
what is the method of solution heat treatment of an aluminum alloy
metal is hardened by heating it in a surface to specified temperature and immediately quenching it in water. It is soft when it is removed from the quench, but as it ages it hardeneds
what is the method of precipitation heat treating of an aluminum alloy
the metal is heated and quenched, then it is returned to the oven and heated to a lower temp. it is held at this temp for a specified time, then removed from the oven and allowed to cool in still air. this increases the strength and hardness of the metal. precipitation heat treating is also called artificial aging
what is another name for precipitation heat treatment
artificial aging
identify and explain the differences between heat-treated and non heat treated aluminum alloys
heat treated alloy designations are normally followed with a -T, followed by a number (1-10) that designates the type of heat treat. a common aircraft aluminum allot is 2024-T3. heat treated aluminum is stronger than non heat treated aluminum
why is it important that a piece of aluminum alloy be quenched immediately after it is removed from the heat treating oven
any delay in quenching aluminum alloy after It is removed from the oven will allow the grain structure to grow enough that intergranular corrosion is likely to form in the metal
describe and explain the forces placed on aircraft materials
tension-
compression-
torsion-
bending-
strain-
shear-
what type of loading should be avoided when using a self-locking nut on an aircraft bolt
a self-locking nut should not be used for any application where there are any rotational forces applied to the nut or to the bolt
what determines the correct grip length of a bolt used in an aircraft structure
the grip length of the bolt should be the same as the combined thickness of the materials being held by the bolt
how tight should the nut be installed on a clevis bolt that is used to attach a cable fitting to a control surface horn
the nut on a clevis bolt should not be tight enough to prevent the clevis bolt from turning in the cable fitting and the horn
what bolt is described by this number: AN6-14A
AN6= Hex bolt,6/16(3/8) inch diameter
14=length=1-4/8(1-1/2) inch long
A=the shank is not drilled for a cotter pin
what is indicated by a triangle on the head of a steel bolt
this is a close tolerance bolt
what is a correct application for self-tapping sheet metal screw on an aircraft
they may be used to hold nonstructural component onto the aircraft
how can you tell when a self-locking nut must be discarded
when you can screw the nut onto a bolt without having to use a wrench
what is a channel nut
a series of nuts mounted loosely in a channel that is riveted to the aircraft structure. you can install screws in a channel nut without having to hold the nut with a wrench
of what two materials are cotter pins made
low-carbon steel and corrosion resistant steel
what is the smallest size cable that is allowed to be used in the primary control system of an aircraft
1/8 inch diameter
what type of control cable must be used when pulleys are used to change the direction of cable travel
extra-flexible cable (7x19)
what is the purpose of safety wire
to prevent a nut, bolt, or other components from loosening
after torquing a castellated nut, can the nut be loosened to align with the hole in a bolt for installing the cotter pin
no. never overtourque or loosen a torque nut to align safety wire or cotter pin holes. the nut should never be torqured to the minimum torque, and the tightened to align with the safety hole, without exceeding the maximum torque
what kind of measuring is used to measure the runout of an aircraft engine crankshaft
a dial indicator
what measuring instrument is used to measure the fit between a rocker arm shaft and its bushings
outside diameter of the shaft is measured with a micrometer caliper. the inside of the bushing is measured with a telescoping gauge and the same micrometer caliper
in what increment can a veneer micrometer caliper be read
one ten thousand (0.0001) inch
what is an advantage of vernier caliper over a micrometer caliper
the range of a vernier caliper if far greater than that of a micrometer caplier
what precision tool is used to measure piston ring side clearance
thickness gauge
what precision tools are used to measure the inside diameter of a cylinder
a telescoping gauge and micrometer caliper
what precision tools are used to measure the inside diameter of a small hole
a small hole gauge and micrometer caliper
what kind of solder is recommended for soldering electrical wires
60/40 resin-core solder
what is the function of the flux used in soldering
flux covers the cleaned and heated metal to keep oxygen away from it so oxides cannot form. oxides keep the solder from adhering to the surface of the metal
what are the three most common types of torque wrench
deflecting beam, dialing indicating, and micrometer setting types
where would an aviation mechanic find the appropriate hardware specifications for use on a particular aircraft
in the aircraft manufacturers structural repair manual (SRM)
where would an aviation mechanic find the material specifications for structural repairs on an aircraft
in the aircraft manufacturer illustrated parts catalog (IPC)
why is it scratched that the surface of a piece of clad aluminum alloy not to be scratched
the pure aluminum used for the cladding is non corrosion, but the aluminum alloy below the cladding is susceptible to corrosion. if the cladding is scratched through, corrosion could form
what is the preload value when torquing a nut
preload is the force or torque required to overcome the friction between the threads on the nut and the thread of the bolt prior to the nut containing the mating surface
how is the preload value used when torquing a nut
the preload torque is added to the specific torque to obtain the required setting on the torque wrench
how can the material of a bolt be identified
by manufacturer markings that are on the bolt head
how is the welding flux removed from a piece of aluminum that has been gas-welded
it should be removed by scrubbing it with hot water and a bristle brush
what are the visual characteristics of a good weld
a good weld is uniform in width; the ripples are even and well feathered into the base metal an show no burn due to overheating. the weld has good penetration and is free of gas pockets, porosity, or incursions
what are the visual characteristics of a bad weld
a bad weld has irregular edges and considered variation in the depth of penetration. it often has the appearance of a cold weld
what must be done to welded joint if it must be rewelded
all traces of the old weld must be removed so the new weld will penetrate the base metal
what is meant by normalizing a piece of steel after it has been welded or machined
normalizing removes stresses that are locked into the material by welding or machining
how I steel structure normalized after it has been welded
heat the steel structure to a temperature above its critical temperature and allow it to cool in still air
what determines the size of tip that is to be used when gas-welding steel
the thickness of the material being welded. the size of the tip orifice determines the amount of flame produced and thus the amount of heat put into the metal
