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General A&P Oral > Aircraft Materials, Hardware, and Processes > Flashcards

Aircraft Materials, Hardware, and Processes Flashcards

1
Q

What is the alloy number or the most commonly used aluminum alloy for aircraft structural use?

A

2024-T

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2
Q

What is the alloy number of a high strength aluminum alloy that has zinc as an alloying component?

A

7075

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3
Q

What type of composite material is used when stiffness is the prime requirement?

A

Graphite (carbon)

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4
Q

What type of composite material is used when toughness is the prime requirement?

A

Kevlar

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5
Q

Why is a piece of steel tempered after it has been hardened?

A

When steel is hardened, it becomes brittle. Tempering removes some of this brittleness.

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6
Q

How is steel annealed?

A

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.

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7
Q

How is steel hardened?

A

It is heated to its critical temperature and quenched in water, brin, or oil.

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8
Q

What is meant by tempering steel?

A

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

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9
Q

What is meant by case hardening?

A

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

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10
Q

What are two methods of case hardening?

A

Carburizing and nitriding.

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11
Q

How is steel nitrided?

A

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 of the surface of the steel.

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12
Q

What is the method of solution heat treatment of an aluminum alloy?

A

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.

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13
Q

What is the method of precipitation heat treating of an aluminum alloy?

A

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. Precipitation heat treating is also called artificial aging.

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14
Q

What is another name for precipitation heat treatment?

A

Artificial aging.

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15
Q

Identify and explain the differences between heat-treated and non-heat-treated aluminum alloys.

A

Heat-treated aluminum 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 alloy is 2024-T3. Heat-treated aluminum is stronger than non-heat-treated aluminum.

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16
Q

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

A

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.

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17
Q

What are the forces that can be placed on aircraft materials?

A

Tensioin, compression, torsion, bending, strain, and shear.

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18
Q

Describe tension.

A

A force tending to stretch or elongate the material.

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19
Q

Describe compression.

A

A force tending to compress or shrink.

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20
Q

Describe bending.

A

A perpendicular force on the longitudinal axis of an object, causing it to flex or bend. The inner surface of the bend will be in compression and the outer surface of the bend will be in tension.

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21
Q

Describe torsion.

A

A twisting force on an object.

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22
Q

Describe strain.

A

The stress of an object which can cause the object to change shape or to become distorted.

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23
Q

Describe shear.

A

A force that tried to cut of slice through an object. The force is parallel to the material cross section.

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24
Q

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

A

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.

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25
Q

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

A

The grip length of the bolt should be the same as the combined thicknesses of the materials being held by the bolt.

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26
Q

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

A

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.

27
Q

What bolt is described by this number: AN6-14A?

A

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.

28
Q

What is indicated by a triangle on the head of a steel bolt?

A

This is a close tolerance bolt.

29
Q

What is a correct application for self-tapping sheet metal screws on an aircraft?

A

They may be used to hold nonstructural components onto the aircraft.

30
Q

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

A

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

31
Q

What is a channel nut?

A

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.

32
Q

Of what two materials are cotter pins made?

A

Low carbon steel and corrosion-resistant steel.

33
Q

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

A

1/8-inch diameter.

34
Q

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

A

Extra-flexible cable (7x19).

35
Q

What is the purpose of safety wire?

A

To prevent a nut, bolt, or other component from loosening.

36
Q

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

A

No. Never over-torque or loosen a torqued nut to align safety wire or cotter pin holes. The nut should be torqued to the minimum torque, and then tightened to align with the safety hole, without exceeding the maximum torque.

37
Q

What kind of measuring instrument is used to measure the runout of an aircraft engine crankshaft?

A

A dial indicator.

38
Q

What measuring instruments are used to measure the fit between a rocker arm shaft and its bushing?

A

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.

39
Q

In what increments can a vernier micrometer caliper be read?

A

One ten thousandth (0.0001) inch.

40
Q

What is an advantage of a vernier caliper over a micrometer caliper?

A

The range of a vernier caliper is far greater than that of a micrometer caliper.

41
Q

What precision tool is used to measure piston ring side clearance?

A

Thickness gauge.

42
Q

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

A

A telescoping gauge and a micrometer caliper.

43
Q

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

A

A small hole gauge and a micrometer.

44
Q

What kind of solder is recommended for soldering electrical wires?

A

60/40 resin-core solder.

45
Q

What is the function of the flux used in soldering?

A

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.

46
Q

What are the three most common types of torque wrenches?

A

Deflecting beam, dial indication, and micrometer setting types.

47
Q

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

A

in the aircraft manufacturer’s illustrated parts catalog (IPC).

48
Q

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

A

In the aircraft manufacturer’s structural repair manual (SRM).

49
Q

Why is it very important that the surface of a piece of clad aluminum alloy not be scrateched?

A

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.

50
Q

What is the preload value when torquing a nut?

A

Preload is the force of torque required to overcome the friction between the threads on the nut and the threads of the bolt prior to the nut contacting the mating surface.

51
Q

How is the preload value used when torquing a nut?

A

The preload torque is added to the specified torque to obtain the required setting on the torque wrench.

52
Q

How can the material of a bolt be identified?

A

By manufacturer markings than are on the bolt head.

53
Q

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

A

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

54
Q

What are the visual characteristics of a good weld?

A

A good weld is uniform in width; the ripples are even and well feathered into the base metal and show no burn due to overheating. The weld has good penetration and is free of gas pockets, porosity, or inclusions.

55
Q

What are the visual characteristics of a bad weld?

A

A bad weld has irregular edges and considerable variation in the depth of the penetration. It often has the appearance of a cold weld.

56
Q

What must be done to a welded joint if it must be rewelded?

A

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

57
Q

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

A

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

58
Q

How is a steel structure normalized after it has been welded?

A

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

59
Q

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

A

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.

60
Q

What are the common PPE items that an aviation mechanic should have access to?

A

Hearing protection, eye protection, gloves, aprons, dust masks, and respirators.

61
Q

What are some of the dangers that could be cause by improper torque?

A

Too low of torque could cause components to loosen and come apart. Too high of torque could cause failure to the bolt or component or cause a rotating component to seize and not function as designed. All of these failures could cause loss of a system, or even loss of an aircraft and potential loss of life.

62
Q

Why is the use of used hardware or suspected unapproved parts (SUPS) undesirable?

A

In addition to creating an unairworthy condition, the risk of failure increases, which could cause damage to a system or the aircraft.

63
Q

Where would an aviation mechanic find the proper procedure for torquing critical, highly stressed fasteners?

A

In the aircraft manufacturer’s maintenance manual.

64
Q

What is the proper technique when using a torque wrench?

A

Pull the wrench assembly with a smooth, steady motion until the proper torque is reached. A fast or jerky motion will result in an improper torque.

General A&P Oral (28 decks)

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