aircraft material, hardware, and process

Question 1

what is the alloy number of the most commonly used aluminum alloy for aircraft structural use

Answer 1

2024-T

Question 2

what is the alloy number of a high strength aluminum ally that has zinc as an alloying compnent

Answer 2

7075

Question 3

what type of composite material is used when stiffness is the prime requirement

Answer 3

graphite (carbon)

Question 4

what type of composite material is used when toughness is the prime requirement

Answer 4

kevlar

Question 5

why is a piece of steel tempered after it has been hardened

Answer 5

when steel is hardened it becomes brittle. tempering removes some of its brittleness

Question 6

how is steel annealed

Answer 6

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

Question 7

how it steel hardened

Answer 7

it is heat to its critical temperature and then quenched in water, brine, or oil

Question 8

what is meant by tempering steel

Answer 8

steel is first hardened; then some of the hardness is removed to relieve some of the internal stresses and brittleness

Question 9

what is meant by case hardening

Answer 9

the surface of the metal is hardened by the infusion of carbon or aluminum nitride. the interior of the metal remains strong and tough

Question 10

what are two methods of case hardening

Answer 10

carburizing and nitrating

Question 11

how its steel nitrided

Answer 11

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

Question 12

what is the method of solution heat treatment of an aluminum alloy

Answer 12

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

Question 13

what is the method of precipitation heat treating of an aluminum alloy

Answer 13

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

Question 14

what is another name for precipitation heat treatment

Answer 14

artificial aging

Question 15

identify and explain the differences between heat-treated and non heat treated aluminum alloys

Answer 15

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

Question 16

why is it important that a piece of aluminum alloy be quenched immediately after it is removed from the heat treating oven

Answer 16

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

Question 17

describe and explain the forces placed on aircraft materials

Answer 17

tension-
compression-
torsion-
bending-
strain-
shear-

Question 18

what type of loading should be avoided when using a self-locking nut on an aircraft bolt

Answer 18

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

Question 19

what determines the correct grip length of a bolt used in an aircraft structure

Answer 19

the grip length of the bolt should be the same as the combined thickness of the materials being held by the bolt

Question 20

how tight should the nut be installed on a clevis bolt that is used to attach a cable fitting to a control surface horn

Answer 20

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

Question 21

what bolt is described by this number: AN6-14A

Answer 21

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

Question 22

what is indicated by a triangle on the head of a steel bolt

Answer 22

this is a close tolerance bolt

Question 23

what is a correct application for self-tapping sheet metal screw on an aircraft

Answer 23

they may be used to hold nonstructural component onto the aircraft

Question 24

how can you tell when a self-locking nut must be discarded

Answer 24

when you can screw the nut onto a bolt without having to use a wrench

Question 25

what is a channel nut

Answer 25

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

Question 26

of what two materials are cotter pins made

Answer 26

low-carbon steel and corrosion resistant steel

Question 27

what is the smallest size cable that is allowed to be used in the primary control system of an aircraft

Answer 27

1/8 inch diameter

Question 28

what type of control cable must be used when pulleys are used to change the direction of cable travel

Answer 28

extra-flexible cable (7x19)

Question 29

what is the purpose of safety wire

Answer 29

to prevent a nut, bolt, or other components from loosening

Question 30

after torquing a castellated nut, can the nut be loosened to align with the hole in a bolt for installing the cotter pin

Answer 30

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

Question 31

what kind of measuring is used to measure the runout of an aircraft engine crankshaft

Answer 31

a dial indicator

Question 32

what measuring instrument is used to measure the fit between a rocker arm shaft and its bushings

Answer 32

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

Question 33

in what increment can a veneer micrometer caliper be read

Answer 33

one ten thousand (0.0001) inch

Question 34

what is an advantage of vernier caliper over a micrometer caliper

Answer 34

the range of a vernier caliper if far greater than that of a micrometer caplier

Question 35

what precision tool is used to measure piston ring side clearance

Answer 35

thickness gauge

Question 36

what precision tools are used to measure the inside diameter of a cylinder

Answer 36

a telescoping gauge and micrometer caliper

Question 37

what precision tools are used to measure the inside diameter of a small hole

Answer 37

a small hole gauge and micrometer caliper

Question 38

what kind of solder is recommended for soldering electrical wires

Answer 38

60/40 resin-core solder

Question 39

what is the function of the flux used in soldering

Answer 39

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

Question 40

what are the three most common types of torque wrench

Answer 40

deflecting beam, dialing indicating, and micrometer setting types

Question 41

where would an aviation mechanic find the appropriate hardware specifications for use on a particular aircraft

Answer 41

in the aircraft manufacturers structural repair manual (SRM)

Question 42

where would an aviation mechanic find the material specifications for structural repairs on an aircraft

Answer 42

in the aircraft manufacturer illustrated parts catalog (IPC)

Question 43

why is it scratched that the surface of a piece of clad aluminum alloy not to be scratched

Answer 43

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

Question 44

what is the preload value when torquing a nut

Answer 44

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

Question 45

how is the preload value used when torquing a nut

Answer 45

the preload torque is added to the specific torque to obtain the required setting on the torque wrench

Question 46

how can the material of a bolt be identified

Answer 46

by manufacturer markings that are on the bolt head

Question 47

how is the welding flux removed from a piece of aluminum that has been gas-welded

Answer 47

it should be removed by scrubbing it with hot water and a bristle brush

Question 48

what are the visual characteristics of a good weld

Answer 48

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

Question 49

what are the visual characteristics of a bad weld

Answer 49

a bad weld has irregular edges and considered variation in the depth of penetration. it often has the appearance of a cold weld

Question 50

what must be done to welded joint if it must be rewelded

Answer 50

all traces of the old weld must be removed so the new weld will penetrate the base metal

Question 51

what is meant by normalizing a piece of steel after it has been welded or machined

Answer 51

normalizing removes stresses that are locked into the material by welding or machining

Question 52

how I steel structure normalized after it has been welded

Answer 52

heat the steel structure to a temperature above its critical temperature and allow it to cool in still air

Question 53

what determines the size of tip that is to be used when gas-welding steel

Answer 53

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