material and processses Flashcards
what is the proper type of nondestructive inspection to use for locating surface cracks in an aluminum alloy casting or forging?
zyglo or dye pnentrant
what inspection method would be most appropriate for checking a nonferrous metal part for inter-granular corrosion?
eddy curd\rent inspection
what inspection method would be most appropriate for checking the internal structure of an airplane wing for corrosion?
x-ray inspection
how does filiform corrosion usually appear on an aircraft structure
as thread-like lines of puffiness under a film of polyurethane or other dense finish system topcoats
what inspection method would be most appropriate for checking a steel landing gear component for stress cracks
magnetic particle inspection
what type of inspection is best suited for detecting a fault within a piece of nonferrous metal?
ultrasonic inspection
explain the procedure to use when making a dye penetrant inspection of a part
clean the part thoroughly, apply the penetrant, and allow it to soak for the recommended dwell time. Remove all of the penetrant from the surface and apply the developer.
why is it important that all parts be thoroughly cleaned before they are inspected by the dye penetrant method?
any grease or dirt in a faul will keep the penetrant from seeping into the fault
explain the procedure to use when performing a magnetic particle inspection of a part
thoroughly clean the part, magnetize it as directed by the appropriate service manual, flow the indicating medium over the surface, and inspect it under a “black” light. when the inspection is complete, thoroughly demagnetize the part
why is it necessary to magnetize a part both circularly and longitudinally when inspecting a steel part by the magnetic particle method?
to detect faults that extend across as well as lengthwise within the part
does cicular magntization detect parts that are across or lengthwise to the part?
lengthwise
why is it important that all engine parts which have been inspected by the magnetic particle method be completely demagnetized?
if the parts are not completely demagnetized, they will attract steel particles that are produced by engine wear and will cause damage to bearing surfaces
what is the principle of eddy current inspection?
a current is induced into the metal being tested by a test probe. the amount of induced current is determined by the conductivity, mass, and permeability of the material, and the presence of any faults or voids.
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 within the 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
explain the way a steel structure is 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
why is a piece of steel tempered after it has been hardened?
when steel is hardened, it becomes brittle, tempering removes some of this brittleness.
how is steel annealed?
it is heated to just above its upper critical temperature until it reaches a uniform temperature throughout, then it is allowed to cool very slowly in the oven
how is steel hardened?
it is heated to its critical temperature and quenched in water, brine, or oil
what is meant by tempering steel?
the 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 nitriding
how is steel nitrided
the steel part is heated in a retort in which there is an atmosphere of ammonia(a 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
describe the method of solution heat treatment of an aluminum alloy.
the metal is hardened by heating it in a furnace to a specified temperature and immediately quenching it in water. it is soft when it is removed from the quench, but as it ages it regains its hardness.
describe the method of precipitation heat treating of aluminum alloy
the metal is heated and quenched, then it is returned to the oven and heated to a lower temperature. it is held at this temperature 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.
what is another name for precipitation heat treatment?
artificial aging
what is meant by an icebox rivet?
A rivet made of 2017 or 2024 aluminum alloy. these rivets are heat-treated and quenched, then stored in a sub-freezing ice box until they are ready to be used. the cold storage delays the hardening of the rivet.
what are the two most commonly used rivet heads?
MS20470 universal head and MS20426 100 degree countersunk head.
what alloy is identified by the following rivet codes?
A,AD,D,DD,B
A is 1100 aluminum AD is 21170-T aluminum alloy D is 2017-T aluminum alloy DD is 2024-T aluminum alloy B is 5056-T aluminum alloy
what mark on the head of a rivet identifies the following alloys: 2117-T, 2017-T, 2024-T, 5056-T
2117-T recesse dot
2017-T raised dot
2024-T raised double dash
5056-T raised cross
what is the meaning of this rivet designation: MS20470AD4-6
MS20470= universal head AD = 2117-T aluminum alloy 4 = 4/32 (1/8) inch diameter 6 = 6/16 (3/8) inch long
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 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 thicknesses 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 of 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 head 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 screws on an aircraft?
they may be used to hold nonstructural components 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 (7 x 19)
what is the basic wood used for aircraft wing spars?
sitka spruce
what type of fabric is most widely used for covering aircraft structures?
heat-shrinkable polyester fabric
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 alloy that has zinc as an alloying component?
7075
why is it very important that the surface of a piece of clad aluminum alloy no be scratched?
the pure aluminum used for the cladding is noncorrosive, but the aluminum alloy below the cladding is susceptible to corrosion. if the cladding is scratched through, corrosion could form
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
explain the way a piece of aluminum alloy is solution heat-treated.
the aluminum is heated in an oven to the proper temperature for a specified time; then it is removed and quenched in water
what is meant by precipitation heat treatment of a piece of aluminum alloy?
after a piece of aluminum has been solution heat-treated, it is held at a specified elevated temperature for a period of time. precipitation heat treating is also called artificial aging.
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
how does filiform corrosion usually appear on an aircraft structure?
as thread-like lines of puffiness under a film of polyurethane or other dense finish system topcoats
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
how is the welding flux removed from a piece of aluminum that has been gas-welded?
it should be removed by scrubbing it with not water and a bristle brush
what must be done to a welded joint if it must be re-welded?
all traces of the weld must be removed so the new weld will penetrate the base metal
what kind of measuring instrument is used to measure the run-out of an aircraft engine crankshaft?
a dial indicator
what measuring instruments are used to measure the fit between a rocker arm shaft and its bushing?
the 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
what precision tool is used to measure the piston ring side clearance?
thickness gage
what precision tools are used to measure the inside diameter of a cylinder?
a telescoping gauge and a micrometer caliper
what precision tools are used to measure the inside diameter of a small hole?
a small hole gauge and a micrometer caliper
