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A&P - Airframe > Aircraft Electrical System > Flashcards

Aircraft Electrical System Flashcards

1
Q

Some electric motors have two sets of field windings wound in opposite directions so that the

A

motor can be operated in both directions

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2
Q

One purpose of a growler test is to determine the presence of

A

a shorted armature

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3
Q

Electric wire terminals for must aircraft applications must be what type?

A

Ring

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4
Q

What is the principal advantage of the series wound dc motor?

A

High starting torque

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5
Q

If a generator is equipped with a vibrator type voltage regulator, the actual time the voltage regulator point remain open

A

depends on the load carried by the regulator

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6
Q

What is the cause of generator brush arcing?

A

Low spring tension

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7
Q

When ac generators are operated in parallel, the

A

frequency and voltage must be both be equal

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8
Q

The starting current of a series wound dc motor in passing through the field and armature windings, produces a

A

high starting torque

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9
Q

Which motor would be most likely to have an armature brake?

A

Landing light retraction motor

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10
Q

The method most often used in overcoming the effect of armature reaction is through the use of

A

interpoles

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11
Q

The only practical method of maintaining a constant voltage output from an aircraft generator under varying conditions of speed and load is to vary the

A

strength of the magnetic field

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12
Q

The pole pieces or shoes used in DC generators are a part of the

A

field assembly

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13
Q

How many cycles of AC voltage are produced in a six pole alternator of the revolving field type for each revolution of the rotor?

A

Three

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14
Q

If the reverse current cutout relay points fail to open after the generator output has dropped below battery potential, current will flow through the generator armature

A

opposite the normal direction and through the shunt field in the normal direction

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15
Q

How does the magnetic brake used to stop rotation of an electric motor armature operate?

A

A friction brake is applied by a spring and released by a magnet

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16
Q

In a generator, what eliminates any possible sparking to the brush guides caused by the movement of the brushes within the holder?

A

The brush pigtail

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17
Q

A series wound dc electric motor will normally require

A

more current at low RPM than high RPM

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18
Q

The type of electric wire terminals used for most aircraft applications, in addition to providing good current carrying capabilities, are designed primarily

A

to prevent circuit failure due to terminal disconnection

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19
Q

Aluminum wire must be stripped very carefully because

A

individual strands will break easily after being nicked

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20
Q

The commutator of a generator

A

changes alternating current produced in the armature into direct current as it taken from the armature

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21
Q

An ammeter in a battery charging system is for the purpose of indicating the

A

rate of current used to charge the battery

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22
Q

Which of the following is not one of the purpose of interpoles in a generator?

A

Reduce field strength

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23
Q

To test generator or motor armature windings for opens

A

place armature in a growler and connect a 100V test light on adjacent segments; light should light

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24
Q

What is the color and orientation of the position lights for navigation on civil airplanes?

A

Left side - red
Right side - green
Rear aft - white

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25
Q

To what depth is the mica insulation between the commutator bars of a DC generator undercut?

A

Equal to the width of the mica

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26
Q

A voltage regulator controls generator output by

A

varying current flows to generator field coil

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27
Q

Which type of DC generator is not used as an airplane generator?

A

Series wound

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28
Q

What is the most accurate type of frequency measuring instrument?

A

Integrated circuit chip having a clock circuit

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29
Q

During ground operation, aircraft generator cooling is usually accomplished by

A

an integral fan

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30
Q

What does a rectifier do?

A

Changes alternating current into direct current

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31
Q

What type of instrument is used for measuring very high values of resistance?

A

Megohmmeter

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32
Q

When a diode is checked for an open circuit or a short circuit, it should be

A

disconnected from the circuit

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33
Q

When handling a high voltage capacitor in an electrical circuit, be sure it

A

is fully charged before removing it from circuit

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34
Q

Which of the following is most likely to cause thermal runaway in a nickel-cadmium battery?

A

Excessive current draw from the battery

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35
Q

How can it be determined if a transformer winding has some of its turns shorted together?

A

The transformer will get hot in normal operation

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36
Q

Which of the following are the major parts of a dc motor?

A

Armature assembly, field assembly, brush assembly and end frame

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37
Q

No.1 There are three basic types of DC motors; series shunt and compound
2. In the series motor, the field windings, consistings of relatively few turns of heavy wire, are connected in series with the armature winding

A

Both No.1 and No.2 are true

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38
Q

What is the appropriate method for installing pre-insulated terminal plugs and splices to electrical wires?

A

Using a crimping tool to secure the terminal lug

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39
Q

Which of the following factors must be taken into consideration when determining the wire size to use for an aircraft installation?

A

Allowable power loss, permissible voltage drop, current carrying capability of the conductor, type of load

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40
Q

When selecting hardware for attaching bonding connections to an aircraft structure, which of the following should be considered?

A

Mechanical strength, ease of installation, amount of current to be carried

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41
Q

How should the splices be arranged if several are to be located in an electrical wire bundle?

A

Staggered across the length of the bundle

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42
Q

What is the minimum bend radius for an electrcial wire bundle

A

Ten times the outside diameter of the bundle

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43
Q

When approved, splices may be used to repair manufactured harnesses or installed wiring. The maximum number of splices permitted between any two connectors is

A

one

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44
Q

Electrical connectors used in aircraft assemblies should meet which of the following specifications?

A

Military Specifications (MS)

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45
Q

The most common method of attaching a pin or socket to an individual wire in an MS electrical connector is by

A

crimping

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46
Q

The pin section of an AN/MS connector is normally installed on

A

the ground side of a circuit

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47
Q

The voltage output of an alternator may be regulated by controlling the

A

voltage output of the DC exciter

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48
Q

If several long lengths of electrical cable are to be installed in rigid conduit, the possibility of damage to the cable as it pulled through the conduit will be reduced by

A

dusting the cable powdered soapstone

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49
Q

Grounding is electrically connecting a conductive object to the primary structure. One purpose of grounding is to

A

prevent development of radio frequency potentials

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50
Q

What is normally used to bond non-continuous stainless steel aircraft components

A

Copper jumpers

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51
Q

Aircraft fuse capacity id rated in

A

amperes

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52
Q

When adding a rheostat to a light circuit to control the light intensity; it should be connected in

A

series with the light

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53
Q

Circuits that must be operated only in an emergency or whose inadvertent activation could endanger a system frequently employ

A

guarded switches

54
Q

If one switch is used to control all navigation lights, the lights are most likely connected

A

parallel to each other and in series with the switch

55
Q

Oil canning of the sides of aluminum of steel electrical junction boxes is considered to be

A

a shorting hazard

56
Q

Electric wiring installed in aircraft without special enclosing means (open wiring) offers the advantage of ease of installation, simple maintenance and reduced weight. When bundling open wiring, the bundles should

A

be limited as to the number of cables to minimize damage from a single electrical fault

57
Q

During inspection of the terminal strips of an aircraft electrical system, it should be determined that

A

the terminal studs are anchored against rotation

58
Q

What protection to wires and cables does conduit provide when used in aircraft installations?

A

Mechanical

59
Q

Which of the following should be accomplished in the installation of aircraft wiring?

A

Locate the bundle above flammable fluid and securely clamp to structure

60
Q

If the (+) terminal of a voltmeter is connected to the (-) terminal of the source voltage and the (-) terminal of the meter is connected to the (+) terminal of the source voltage, the voltmeter will read

A

backwards

61
Q

When using the voltage drop method of checking circuit resistance, the

A

input voltage must be maintained at a constant value

62
Q

The nominal rating of electrical switches refers to continuous

A

current rating with the contact closed

63
Q

Aircraft electrical junction boxes located in a fire zone are usually constructed of

A

stainless steel

64
Q

To help minimize radio interference in a capacitor will largely eliminate and provide a steady direct current if the capacitor is connected to the generator in

A

parallel

65
Q

The primary considerations when selecting electric cable size are

A

current carrying capacity and allowable voltage drop

66
Q

The navigation lights of some aircraft of some aircraft consist of single circuit controlled by a single switch which has as ON and OFF position, with no additional position possible. This switch is referred to as a

A

single pole, single throw (SPST), two position switch

67
Q

Electric circuits are protected from over heating by

A

fuses

68
Q

How should co axial cable be routed?

A

As directly as possible

69
Q

Which of the following copper electrical cable sizes should be selected to replace a No.6 aluminum electrical cable?

A

No. 6

70
Q

In installations where the ammeter is in the generator or alternator lead, and the regulator system does not limit the maximum current that the generator or alternator can deliver, the ammeter can be redlined at what percent of the generator or alternator rating?

A

100%

71
Q

Which statement rating relating to electrical wiring is true?

A

When attaching a terminal to the end of an electric cable, it should be determined that the strength of the cable to terminal joint is at least to the tensile strength of the cable itself

72
Q

Bonding connections should be tested for

A

resistance value

73
Q

What kind of switch should you install in a single wire circuit that required the switch to be manually held in the ON position?

A

Single pole, single throw (SPST) two position normally open

74
Q

A circuit breaker is installed in an aircraft electrical system to primarily to protect the

A

circuit and should be located as close to the source as possible

75
Q

How should a voltmeter be connected?

A

In parallel with a load

76
Q

A circuit protection device called a current limiter is essentially a slow blow fuse and is designed to be used in

A

heavy power circuits

77
Q

If it is necessary to use an electrical connector where it may be exposed to moisture, the mechanic should

A

use a special moisture proof type

78
Q

Which of the following are considered circuit protective devices that are used in aircraft electrical systems?

A

Circuit breakers, fuses and current limiters

79
Q

If a wire is installed so that it comes into contact with some moving parts, what protection should be given to the wire?

A

Pass through conduit

80
Q

In the American Wire Gauge (AWG) system of numbers, used to designate electrical wire sizes, the number assigned to a size is related to its

A

cross-sectional area

81
Q

What is the allowable voltage drop for a No. 18 copper wire 50 feet long to carry 12.5 amps, continuous operation?
Use formula VD=RLA
VD = Voltage drop
R = Resistance per ft = .00644
L = Length of wire
A = Amperes

A

4V

82
Q

What is the purpose of the selection of derated switches for known continuous load current applications?

A

To obtain reasonable switch efficiency and service life

83
Q

What is the advantage of a circuit breakers compared to a fuse?

A

It is resettable and resusble

84
Q

What is the advantage of a current limiter?

A

It will take overload for a short period

85
Q

What should be used to protect wires from chafing when they must pass through bulkheads, firewalls, ribs, etc?

A

Suitable grommet

86
Q

In aircraft electrical system, automatic circuit breakers

A

should not be used as circuit protective devices

87
Q

When considering an alteration, the criteria upon which the selection of electric cable size should be based are

A

current-carrying capacity and allowable voltage drop

88
Q

What is an important factor in selecting aircraft fuses?

A

Capacity matches the needs of the circuit

89
Q

The circuit breaker in the instrument lighting system protects the

A

wiring from too much current

90
Q

One advantage of using AC electrical power in aircraft is

A

greater ease in stopping voltage going up or down

91
Q

Why are the iron cores of most induction coils laminated?

A

To reduce the effects of eddy currents

92
Q

Certain transport aircraft us AC power for all normal operation and battery furnished DC electrical power for standby emergency use. In aircraft of this type that operate no DC generators, the batteries are kept charged by

A

rectifiers which use the aircrafts AC generators as a source of power

93
Q

The voltage in an AC transformer secondary that contains twice as many loops as the primary will be

A

greater and the amperage less than in the primary

94
Q

If the positive field lead between a generator and a generator control panel breaks and is shorted while the engine is running, a voltmeter connected to generator out-put would indicate

A

residual voltage

95
Q

What is a method used for restoring generator field residual magnetism?

A

Flash the fields

96
Q

The major advantages of alternating currents (AC) over direct current is the fact that its current and voltage can be easily be increased and decreased

A

by means of a transformer

97
Q

Which of the following must be accomplished when installing an anti collision light?

A

Install a switch independent of the position light switch

98
Q

The inductor type inverter output voltage is controlled by the

A

DC stator field current

99
Q

When using an ohmmeter to check the continuity of a generator field coil, the coil should

A

show very low resistance if it is a series field coil

100
Q

The strength of the core of an electromagnet depends upon the material from which it is constructed and which of the following?

A

The numbers of turn of wire in the coil and the amount of current (amps) passing through the coil

101
Q

A voltage regulator controls generator voltage by changing the

A

resistance of the generator field circuit

102
Q

The overvoltage control automatically protects the generator system when excessive voltage is present by

A

opening the shunt field circuit

103
Q

When DC generators are operated in parallel and to supply power for a single load, their controls include an equalizer circuit to assure that all generators share the load equally. The equaliser circuit operates by

A

increasing the output of the low generator and decreasing the output of the high generator until they are equal

104
Q

What is the maximum amount of time a circuit can be in operation and still be an intermittent duty circuit?

A

Two minutes

105
Q

The most common method of regulating the voltage output of a compound DC generator is to vary the

A

current flowing through the shunt field coils

106
Q

If any one generator in a 24 volt DC system shows low voltage, the most likely cause is

A

an out of adjustment voltage regulator

107
Q

How can the direction of rotation of a DC electric motor be changed?

A

Reverse the electrical connections to either the field or armature windings

108
Q

Static inverters are electronic devices that change DC to AC with the

A

use of an oscillator

109
Q

Aircraft which operate only AC generators (alternators) as a primary source of electrical power normally provide current suitable for battery charging through the use of

A

a step down transformer and rectifier

110
Q

During inspection of an anti collision light for condition and proper operation, it should be determined that

A

the anti-collision light can be operated independently of the position light

111
Q

Major adjustments on equipment such as regulators, contactors and inverters are best accomplished outside the airplane on test benches with necessary instruments and equipment. Adjustment procedure should be outlined by

A

the equipment manufacturer

112
Q

A battery generator system provides direct current. On installations requiring alternating current from the battery generator system, it is necessary to have

A

an inverter

113
Q

An aircraft electrical circuit control relay is

A

an electrically operated switch

114
Q

A relay is

A

a magnetically operated switch

115
Q

The purpose of a rectifier in an electrical system is to change

A

alternating current to direct current

116
Q

What is the ratio of turns between the primary coil winding and the secondary coil winding of a transformer designed to triple its input voltage?

A

Primary will have one third as many turns as its secondary

117
Q

In an AC circuit with no phase lead or lag, which is true?

A

Real power equals apparent power

118
Q

How are generators rated?

A

Amperes at rated voltage

119
Q

How is a shunt-wound DC generator connected?

A

Both fields are shunted across the armature

120
Q

The poles of a generator are laminated to

A

reduce eddy current losses

121
Q

What is the frequency of an alternator dependent upon

A

RPM

122
Q

Where is the generator rating and performance data located?

A

reduce eddy current losses

123
Q

Residual voltage is a result of magnetism in the

A

fieldn shoes

124
Q

In troubleshooting an electrical circuit, if an ohmmeter is properly connected across a circuit component and some value of resistance is read

A

the component has continuity and is not open

125
Q

CSD generators are usually cooled by

A

oil spray

126
Q

A CSD unit drives a generator through the use of

A

a variable hydraulic pump and hydraulic motor

127
Q

Integrated drive generators (IDG) employ a type of high output AC generator that utilizes

A

a brushless system to produce current

128
Q

If the Integrated Drive Generators (IDG) scavenge filter is contaminated with pieces of metal you should

A

remove and replace the IDG

129
Q

When necessary during operation, CSD disconnect is usually accomplished by

A

a switch in the cockpit

130
Q

A CSD unit that is disconnected in flight, due to malfunction such as over temp may be reconnected

A

only on the ground by maintenance personnel

A&P - Airframe (18 decks)

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