ACM-170 KING QUESTIONS Flashcards
(303 cards)
1
Q
What kind of wire can be substituted for aluminum wire?
A
Copper
2
Q
What does substituting copper wire for aluminum wire allow you to do?
A
Decrease the wire size by 2 sizes.
(increase gauge wire)
3
Q
What copper electrical cable size should be used to replace a #6 aluminum electrical cable?
A
Copper #8
4
Q
What is the smallest size of aluminum wire allowed to be used in aircraft?
A
6 gauge
5
Q
What are the primary considerations when selecting cable size?
A
- Current carrying capability of the conductor
- Type of load (continuous / intermittent)
- Allowable power loss
- Permissible voltage drop
6
Q
What is the allowable voltage drop for a #18 copper wire 50’ long to carry 12.5 amperes, continuous operation?
VD = Voltage Drop
R = Resistance p/ft. = 00644
L = Length of wire
A = Amperes
A
VD = RLA
0.00644 X 50 ft. 12.5 amps
VD = 4 volts
7
Q
8841
Which of the following factors must be taken into consideration when determining the wire size to use for an aircraft installation?
1. Mechanical strength
2. Allowable power loss
3. East of installation
4. Resistance of current return path through the aircraft structure
5. Permissible voltage drop
6. Current carrying capability of the conductor
7. Type of load (continuous or intermittent)
A. 2, 5, 6, 7
B. 1, 2, 4, 5
C. 2, 4, 6, 7
A
A
8
Q
8871
Which of the following copper electrical cable sizes should be selected to replace a #6 aluminum electrical cable?
A. #4
B. #6
C. #8
A
C
9
Q
8882
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. Combined resistance and current-carrying capacity
B. Current-carrying capacity
C. Cross-sectional Area
A
C
10
Q
8883
What is the allowable voltage drop for a #18 copper wire 50’ long to carry 12.5 amperes, continuous operation?
Use the formula VD = RLA
VD = Voltage Drop
R = Resistance per ft. = .00644
L = Length of wire
A = Amperes
A. 1/2v
B. 1v
C. 4v
A
C
11
Q
8890
When considering an alteration, the criteria upon which the selction of electric cable size should be based are:
A. Applied voltage and allowable voltage drop.
B. Current-carrying capacity and allowable voltage drop.
C. Current-carrying capacity and applied voltage.
A
B
12
Q
What are the advantages of open wiring?
A
- Ease of installation
- Simple maintenance
- Reduced weight
13
Q
The number of cables in a bundle is limited by _____.
A
The number of cables
14
Q
When installing electrical wiring near flammable fluid lines, what precautions should be taken?
A
- Above the flammable fluid lines
- Securely clamp them to the structure
15
Q
When splices in wires in approved, what is the rule?
A
Only 1 splice is allowed between any 2 connectors.
16
Q
What is the rule when you have several splices in an electrical bundle?
A
Splices should be staggereed along the length of the bundle.
17
Q
What is the minimum bend radii of a bundle?
A
10 times the outside diameter of the bundle.
18
Q
If an electrical cable in installed through a hole in a bulkhead, firewall, etc how should the wires be protected from chaffing?
A
By using a rubber grommet
19
Q
What are the rules when installing coaxial cable?
A
- Should be secured at 2 ft. intervals.
- Route the cable as directly as possible.
20
Q
8666
When installing coaxial cable, it should be secured firmly along its entire length:
A. At 1ft intervals
B. Wherever the cable sags
C. At 2 ft intervals
A
C
21
Q
8821
Aluminum wire must be stripped very carefully because:
A. High resistance will develop in stripping nicks
B. Stripping nicks can cause short circuits
C. Individual strands will break easily after being nicked.
A
C
22
Q
8843
How should the splices be arranged if several are to be located in an electrical wire?
A. Staggered along the length of the bundle.
B. Grouped together to facilitate inspection.
C. Enclosed in a conduit.
A
A
23
Q
8844
What is the minimum bend radius for an electrical wire bundle?
A. 10 times the outside diameter of the bundle.
B. 5 times the outside diameter of the bundle.
C. 15 times the outside diameter of the bundle.
A
A
24
Q
88455
When approved, splices may be used to repair manufactured harnesses or installed wiring. The maximum numbrer of splices permitted between any 2 connectors is:
A. 1
B. 2
C. 3
A
A
25
8858
Electrical wiring installed in aircraft without special enclosing means (open wiring) offers the advantages of ease of installation, simple maintenance, 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.
B. Include at least one shielded cable to provide good bonding of the bundle to the airframe.
C. Be limited to a minimum bend radius of 5 timest the bundle diameter to avoid excessive stresses on the cable insulation.
A
26
8861
Which of the following should be accomplished in the installation of aircraft wiring?
A. Support the bundle to structure and/or solid fluid lines to prevent chafing damage.
B. Provide adequate slack in the wire bundle to compensate for large changes in temperature.
C. Locate the bundle above flammable fluid lines and securely clamp to structure.
C
27
8867
The primary considerations when selecting electric cable size are:
A. Current-carrying capacity and allowable voltage drop.
B. The voltage and amperage of the load it must carry.
C. The system voltage and cable length.
A
28
8870
How does the routing of coaxial cables differ from the routing of electrical wiring?
A. coaxial cables are routed parallel with stringers or ribs.
B. Coaxial cables are routed at right angles to stringers or ribs.
C. Coaxial cables are routed as directly as possible.
C
29
8887
Where elctric cables must pass through holes in bulkheads, formers, rib, firewalls, etc., the wires should be protected from chafing by:
A. Wrapping with electrical tape.
B. Using a suitable grommet.
C. Wrapping with plastic
B
30
If a wire is installed so that it comes in contact with moving parts, what needs to be done?
Pass the wire through a conduit
31
What is one reason to have a conduit?
To provide mechanical protection
32
If multiple cables are being installed in a rigid conduit how should it be accomplished?
Dust the cable with powdered soapstone to reduce possibility of damaging the cable as it is pulled through the conduit.
33
What is powdered soapstone?
A lubricant for electrical cables
34
What is the strengh requirement for a cable-to-terminal joint?
At least equal to the tensile strength of the cable itself.
35
What is the accepted method of attaching a terminal to a wire?
crimping
36
When inspecting terminal tips of an electrical inspection, what must you determine?
The terminal studs must be anchored against rotation.
37
8805
Electric wire terminals for most aircraft applications must be what type?
A. Slotted
B. Hook
C. Ring
C
38
8820
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
B. For uncomplicated and rapid circuit connection and disconnection
C. For permanent connection to the circuit
A
39
88440
For general electrical used in aircraft, the acceptable method of attaching a terminal to a wire is by:
A. Crimping
B. Soldering
C. Crimping and soldering
A
40
8850
If several long lengths of electrical cable are to be installed in rigid conduit, the possibility of damage to the cable as it is pulled through the conduit will be reduced by:
A. Dusting the cable with powdered graphite
B. Dusting the cable with powdered soapstone
C. Applying a light coat of dielectric grease
B
41
8859
During inspection of the terminal strips of an aircraft electrical system, it should be determined that:
A. Only locknuts have been used for terminal attachment to the studs.
B. The terminal studs are anchored against rotation
C. Only plain nuts and lockwashers have been used for terminal attachment to the studs.
B
42
8860
What protection to wires and cables does conduit provide when used in aircraft installations?
A. Electromagnetic
B. Mechanical
C. Structural
B
43
8873
Which statement relating to electric 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 twice the tensile strength of the cable.
B. 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 equal to the tensile ostrength of the cable itself.
C. All electric cable splices should be covered with soft insulating tubing (spaghetti) for mechanical protection against external abrasion.
B
44
8881
If a wire is installed so that it comes in contact with some moving parts, what protection should be given the wire?
A. Wrap with soft wire solder into a shield
B. Wrap with friction tape
C. Pass through conduit
C
45
What are AN/MS connectors?
Electrical connectors specifically designed to meet military specifications.
46
The PIN section of an AN/MS circuit is installed so the pins are on the ____ side of the circuit?
Ground
47
What is the preferred method to attach a pin or connector to a circuit?
crimping
48
If an electrical connector is exposed to moisture what precaution should be taken?
Use a special moisture-proof type of connector
49
8846
AN/MS electrical connectors are specifically designed to meet:
A. Technical Standard Order (TSO) specificaions
B. Military specificaions
C. International Civil Aviation Organization (ICAO) standards
B
50
8847
The most common method of attaching a pin or socket to an individual wire in an MS electrical connector is by:
A. crimping
B. soldering
C. crimping and soldering
A
51
8848
The pin section of an AN/MS connector is normally installed on:
A. The power supply side of a circuit
B. The ground side of a circuit
C. Either side of a circuit (makes no difference).
B
52
8879
If it is necessary to use an electrical connector where it may be exposed to moisute, the mechanic should:
A. Coat the connector with grease
B. Use a special moisture-proof type
C. Spray the connector with varnish or zinc-chromate
B
53
What is grounding?
Electrically connecting a conductive object to the primary structure.
54
What does grounding accomplish?
Prevents development of radio frequency potential
55
Why are aircraft components bonded?
To allow electrical charges to move through the aircraft structure without causing sparks.
56
Why is radio equipment grounded to the aircraft?
To provide low-impedance ground to minimize radio interference
57
When selecting hardware for attaching bonding connections to an aircraft structure what needs to be considered?
1. Mechanical strength
2. Ease of installation
3. Amount of current to be carried
58
What are copper jumpers used for?
To bond noncontinuous stanless steel aircraft components
59
When attaching copper jumpers, avoid the use of _____.
Solder
60
8662
1.). Use solder to attach bonding jumpers on radio equipment
2.Radio equipment is bonded to the aircraft in order to provide a low-impedence ground and to minimize radio interference from static electrical chages.
Regarding the above statements,
A. Only. #1 is true
B. Both #1 and #2 are true
C. Only #2 is true
C
61
8842
When selecting hardware for attaching bonding connections to an aircraft structure, which of the following should be considered?
1. Mechanical strength
2. Allowable power loss
3. Ease of installation
4. Permissible voltage drop
5. Amount of current to be carried
6. Type of load (continuous or intermittent)
A. 1, 3, 5
B. 4, 5, 6
C. 1, 2, 3
A
62
8851
Grounding is electrically connecting a conductive object to the primary structure. One purpose of grounding is to:
A. Prevent current return paths
B. Allow static charge accumulation
C. Prevent development of radio frequency potentials
C
63
8852
What is normally used to bond noncontinuous stainless steel aircraft components?
A. Stainless steel jumpers
B. Copper jumpers
C. Aluminum jumpers
B
64
8874
Bonding connections should be tested for:
A. Resistance value
B. Amperage value
C. Reactance
A
65
If a junction box is in a fire zone what would it be constructed of?
stainless steel
66
What is the purpose of preventing oil canning?
To prevent internal short circuits
67
What are 3 kinds of protection devices?
1. Fuses
2. Circuit breakers
3. Current limiters
68
What is the job of a fuse?
To protect circuits from overheating
69
The capaticy of fuses is rated in ____.
Amperes
70
What is an important factor in selecting aircraft fuses?
Matching the capacity to the needs of the circuit
71
What are the 2 most commonly used fuse holders
1. Plug in type
2. Clip type
72
What is the purpose of a circuit breaker?
To protect the circuit
73
Where should a circuit breaker be located?
As close to the source as possible
74
What is the advantage of a circuit breaker compared to a fuse.
A circuit breaker is resettable and reusable
75
What is the purpose of a circuit breaker in the instrument lighting system?
To protect the wiring from too much current
76
Automatic reset circuit breakers ____ (should / should not) be used in aircraft electrical systems as circuit protective devices
should not
77
What is a current limiter?
Slow-blow fuse used in heavy power circuits
78
What is the advantage of a current limiter?
It will take an overload for a short period of time without blowing.
79
8853
Aircraft fuse capacity is rated in:
A. Volts
B. Ohms
C. Amperes
C
80
8857
Oil canning of the sides of aluminum or steel electrical junction boxes is considered to be:
A. Normal operation in vibration prone areas
B. A shorting hazard
C. Acceptable operation
B
81
8865
Aircraft electrical junction boxes located in a fire zone are usually constructred of:
A. Asbestos
B. Cadmium-plated steel
C. Stainless steel
C
82
8869
Electrical circuits are protected from overheating by means of:
A. Thermocouples
B. Shunts
C. Fuses
C
83
8876
A circuit breaker is installed in an aircraft electrical system primarily to protect the:
A. Circuit and should be located as close to the source as possible.
B. Circuit and should be located as close to the unit as possible
C. Electrical unit in the circuit and should be located as close to the source as possible.
A
84
8878
A circuit protection device called a curent limiter is essentially a slow-blow fuse and is designed to be used in:
A. 400 cycle AC circuits
B. Heavy power circuits
C. Starter-generator circuits
B
85
8880
The 3 kinds of circuit-protection devices used most commonly in aircraft circuits are:
A. Circuit breakers, resistors, and current limiters
B. Circuit breakers, fuses, and current limiters
C. Circuit breakers, capacitors, and current limiter plug-ins mechanical reset types.
B
86
8885
What is the advantage of a circuit breaker when compared to a fuse?
A. never needs replacing
B. Always eliminates the need of a switch
C. Resettable and reusable
C
87
8886
What is the advantage of a current limiter?
A. It breaks circuit quickly
B. It can be reset easily
C. It will take overload for a short period
C
88
8888
In aircraft electrical systems, automatic reset circuit breakers:
A. Should not be used as circuit protective devices.
B. Are useful where only temporary overloads are normally encountered.
C. Must be used in all circuits essential to safe operation of the aircraft.
A
89
8891
What is an important factor in selecting aircraft fuses?
A. The current exceeds a predetermined value.
B. The voltage rating should be lower than the maximum circuit voltage.
C. Capacity matches the needs of the circuit.
C
90
8892
The circuit breaker in the instrument lighting system protects the:
A. lights from too much current
B. Wiring from too much current
C. Wiring from too much voltage
B
91
What is the nominal rating of an electrical switch?
The continuous current rating with the contacts closed.
92
Why should you use derated switches?
Provides reasonable switch efficiency and service life.
93
What does the switch pole indicate?
How many switches per control
94
What does the switch throws indicate?
directions
95
What is a normally Open (NO) switch?
A switch that if released reverts back to the previous position.
(must be held open)
96
What does a single pole / double throw switch mean?
Throw = number of circuits each pole can complete
97
What is a relay?
Magnetically operated switch
98
What is a micro switch used for?
As a limit switch to control electrical units automatically
99
How should a rheostat be connected?
In series with the light
100
8854
When adding a rheostat to a light circuit to control the light intensity, it should be connected in:
A. Parallel with the light
B. Series with the light
C. Series parallel with the light switch
B
101
8855
Circuits that must be operated only in an emergency or whose inadvertent activation could endanger a system frequently emply:
A. Guarded switches
B. Push-pull-type circuit breakers only (no switches)
C. Spring-loaded to off toggle or rocker switches
A
102
8864
The nominal rating of electrical switches reffers to continuous:
A. Current rating with the contacts open
B. Voltage rating with the contacts closed
C. Current rating with the contacts closed.
C
103
8868
The navigation lights of some aircraft consist of a single circuit controlled by a single switch which has an ON position and an OFF position, with no additional positions possible. This switch is referred to as a:
A. Double-pole, single-throw (DPST), two-position switch
B. Single-pole, double-throw (SPDT), two-position switch
C. Single-pole, single-throw (SPST), two-position switch
C
104
8875
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 (NO).
B. Single-pole, single-throw (SPST), single-position
C. Single-pole, double-throw (SPDT), sincle-position normally open (NO).
A
105
8884
What is the purpose of the selection of derated switches for known continuious load current applications?
A. To calculate the voltage drop across the circuit.
B. To prevent short circuits in the motor field windings.
C. To obtain reasonable switch efficiency and service life.
C
106
8889
A certain swtich is described as a single-pole, double-throw switch (SPDT). The throw of a switch indicates the number of:
A. Circuits each pole can complete through the switch.
B. Terminals at which current can enter or leave the switch.
C. Places at which the operating device (toggle, plunger, etc.) will come to rest and at the same time open or close a circuit.
A
107
8917
A relay is:
A. A magnetically operated switch
B. A device which converts electrical energy to kinetic energy.
C. Any conductor which receives electrical energy and passes it on with little or no resistance.
A
108
8966
Microswitches are used primarily as limit switches to:
A. Limit generator output
B. Control electrical units automatically
C. Prevent overcharging of a battery
B
109
What is shielding?
The process of applying a metallic covering to wiring and equipment to eliminate electromagnetic interference. (EMI).
110
How is EMI caused?
When electromagnetic fields (radio waves) induce high frequency (HF) voltages in a wire or component causing inaccuracies or failure.
111
What is the recommended shielding percentage?
85% or greater.
112
10064
What is the process of applying a metallic covering to wiring and equipment to eliminate electromagnetic interference (EMI)?
A. Shielding
B. Wrapping
C. Diverting
A
113
10065
What is the purpose of using external power?
A. To protect against lighting strikes
B. To start the engine or perform maintenance activities on the aircraft without discharging the battery.
C. To discharge the battery for routine testing.
B
114
What is the most accurate type of frequency measuring instrument?
Integrated circuit chip having a clock circuit
115
What does an ammeter indicate in a charging system?
rate of current used to charge the battery
116
If the ammeter will not limit the maximum amount of current what should be done?
Put a redline at 100% of the generator or alternating current.
117
What does a thermocoupler type ammeter do?
measures radio frequency alternating current
(current heats the wire, then the wire temperature indicates the current.)
118
How is a voltmeter connected when testing a circuit?
In parallel with the load
119
When troubleshooting an electrical circuit with an ohmmeter, and you receive a value of resistance that is read, what does it mean?
component has continuity and is NOT open
120
What will happen if a voltmeter is connected backwards?
Voltmeter will ready negative current
121
When checking continuity of a generator field coil with an ohmmeter, the coil should show very low resistance if it is what type of coil?
Why?
series
When in series the generator field coil carries the entire output
122
What should the ohmmeter show when used to determine the condition of an electrolytic capacitor?
very low resistance, then high resistance.
123
What is a megohmmeter used to measure?
Very high values of resistance
124
8823
An ammeter in a battery charging system is for the purpose of indicating the:
A. Amperage available for use.
B. Total amperes being used in the airplane.
C. Rate of current used to charge the battery.
C
125
8830
What is the most accurate type of frequency-measuring instrument?
A. Integrated circuit chip having a clock circuit.
B. electrodynamoeters using electromagnetic fields.
C. Electromagnets using one peranent magnet.
A
126
8833
What type of instrument is used for measuring very high values of resistance?
A. Megohmmeter
B. Shunt-type ohmmeter
C. Multimeter
A
127
8862
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. Correctly
B. Low voltage
C. Backwards
C
128
8872
In installations where the ammeter is in the genertor or alternator lead, and the regulator systems 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. 50
B. 75
C. 100
C
129
8877
How should a voltmeter be connected?
A. In series with the source
B. In parallel with the load
C. In series with the load
B
130
8902
When using an ohmmeter to check the continuity of a generator field coil, the coil should:
A. Be removed from the generator housing.
B. Show high resistance when the meter prods are connected to the terminals of the coil.
C. Show very low resistance if it is a series field coil.
C
131
8927
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 open
B. Either the component or the circuit is shorted
C. The component has continuity and is not open
C
132
The strength of the core (electromagnetic field) is depends on:
1. Type of material from which the core is constructed.
2. The number of turns of wire in the coil.
3. The amount of current (amps) passing through the coil.
133
What is the purpose of a transormer?
To change the voltage of alternating current
134
What would be the relationship of the primary and secondary coil in a transformer if you want to triple the input voltage?
Secondary coil will have 3 times as many turns as the primary coil.
135
If you have twice as many loops in the secondary coil of a transformer what will be the result?
Voltage will be greater and the amperage will be less than the primary.
136
If a transform winding has some of its turns shorted together, what will happen?
Transformer will get hot due to excessive current
137
The iron core of most transformers are laminated for what reason?
To reduce the effects of eddy currents (induced current).
138
8837
How can it be determined if a transormer winding has some of its turns shorted together?
A. Measure the input voltage with an ohmmeter
B. The output voltage will be high
C. the transformer will get hot in normal operation
C
139
8894
Why are the iron cores of most induction coils laminated?
A. To reduce the core reluctance
B. To increase the core permeability
C. To reduce the effects of eddy currents
C
140
8896
The voltage in an AC transofrmer secondary that contains twice as many loops as the primary will be:
A. Greater and the amperate less than in the primary
B. Greater and the amperage than in the primary
C. Less and the amperage greater than in the primary
A
141
8903
The strength of the core of an electromagnet depends upon the material from which it is constructed and which of the following?
A. The number of turns of wire in the coil and the applied voltage.
B. The number of turns of wire in the coil and the amount of current (amperes) passing through the coil.
C. The size (cross section) and the number of turns of wire in the coil and the applied voltage.
B
142
8919
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.
B. Primary will have twice as many turns as its secondary.
C. Primary will have 3 times as many turns as its secondary.
A
143
What is the behavior of current in a DC circuit
remains constant
144
How do you determine resistance in a series circuit?
Determine the voltage drop at each of the resistors
145
When checking the voltage drop across resistance, what does the input voltage need to be?
constant
146
When connecting batteries in series, what happens to the voltage?
It is added together
147
When connecting batteries in parallel what happens to the voltage?
remains current
148
When a NI-CAD battery gets hot what happens?
The internal resistance goes down and even more current is delivered causing thermal runaway.
149
What causes thermal runway
Excessive current draw
150
8836
Which of the following is most likely to cause thermal runway in a nickel-cadmium battery?
A. A high internal resistance condition.
B. Excessive current draw from the battery.
C. Constant current charging of the battery to more than 100% of its capacity.
B
151
8863
When using the voltage drop method of checking circuit resistance, the:
A. Input voltage must be maintained at a constant value.
B. Output voltage must be maintained at a constant value.
C. Input voltage must be varied.
A
152
8909
Which of the batteries are connected together incorrectly?
A. 1
B. 2
C. 3
C
153
10066
What action can result in excessive cell temperatures leading to electrolyte boiling, rapid deterioration of the cells, and battery failure?
A. Improper cleaning
B. Operating batteries beyond their ambient temperature or charging voltage.
C. Insufficient cooling
B
154
10067
What solution should be applied to lead-acid battery electrolyte spills?
A. Sodium bicarbonate
B. Isopropyl Alcohol
C. Acetic Acid
A
155
What is the advantage of AC?
1. Can be transmitted at a high voltage with a low power loss.
2. Voltage can be easily changed (stepped up / down)
156
What is the result in an AC circuit with no phase lead or lag?
Real power equals apparant power
157
What precaution needs to be taken when handling a high voltage capacitor?
Be sure it is fully discharged before removing it from the circuit
158
What is one way to minimize radio interference?
Insall a capacitor in parallel
159
What does a diode do?
Allows current to only flow in one direction
160
What is the procedure when checking a diode for an open or short circuit?
1. Disconnect it from the circuit
2. Check it in each direction
161
8834
When a diode is checked for an open circuit or a short circuit, it should be:
A. In the circuit
B. Checked with a milliamp ammeter
C. Disconnected from the circuit
C
162
8835
When handling a high voltage capacitor in an electrical circuit, be sure it:
A. Has a full charge before removing it from the circuit
B. Has at least a residual charge before removing it from the circuit
C. Is fully discharged before removing it from the circuit
C
163
8866
To help minimize radio interference a capacitor will largely eliminate and provide a steady direct current if the capacitor is connected to the generator in:
A. Parallel
B. Series
C. Series/parallel
A
164
8893
One advantage of using ac electrical power in aircraft is:
A. That AC electrical motors can be reversed while DC motors cannot.
B. Greater ease in stepping the voltage up or down.
C. The effective voltage is 1.41 times the maximum instantaneous voltage: therefore, less power input is required.
B
165
8899
The major advantages of AC current over DC current is the fact that its current and voltage can easily be increased or decreased.
A. By means of an inverter
B. By means of a rectifier
C. By means of a transformer
C
166
8920
In an AC circuit with no phase lead or lad, which is true?
A. Real power is zero
B. Real power is greater than apparent power
C. Real power equals apparent power
C
167
How are generators rated?
1. Amperes
2. Rated voltage
168
Where is the generator rating normally found?
Stamped on the generator
169
What are the main parts of a DC motor?
1. Armature assembly
2. Field Assembly
3. Brush Assembly
4. End frame
170
If you rotate a coil of wire around an electromagnet what will happen?
You will induce a current in the coil of wire
171
If you induce a current in a coil of wire what will happen?
The 2 magnets will either attract or repel each other and it will become a motor.
172
What is the purpose of the brushes?
To transfer the electrical energy from the rotating parts
173
What does the end frame do?
Holds everything in place
174
What is the purpose magnetic break in an armature assembly?
To stop the rotation of electric motor armature.
Keeps motor from continuing to run
(retracting landing light)
175
What is the purpose of a growler?
To test the armature
176
How do you test a generator or motor armature windings for opens?
* Place in growler
* Connect 110v test light on adjacent segments
* Light should light
177
How do you test a generator or motor armature windings for shorts?
* Connect 110v test light on segment and center post.
* Light should NOT light
178
8804
One purpose of a growler test is to determine the presence of:
A. An out-of-round commutator
B. A broken field lead
C. A shorted armature
C
179
8811
Which motor would be most likely to have an armature brake?
A. Starter motor
B. Landing light ratraction motor
C. Inverter drive motor
B
180
8817
How does the magnetic brake used to stop roatation of an electric motor armature operate?
A. Centrifugal force releases a rotating brake cog from a stationary notch when the armature reaches a certain speed and magnetic force re-engages the cog when the electrical power is turned off.
B. A friction brake is applied by a magnet and released by a spring.
C. A fricetion brake is applied by a spring and released by a magnet.
C
181
8825
To test generator or motor armature windings for opens,
A. Place armature in a growler and connect a 110v test light on adjactent segments; light should light.
B. Check adjacent segments on commutator with an ohmmeter on the high resistance scale.
C. Use a 12/24v test light between the armature core segments and the shaft.
A
182
8838
Which of the following are the major parts of a DC motor?
1. Armature assembly
2. Field assembly
3. Brush assembly
4. Commutator
5. Pole piece
6. Rheostat
7. End frame
A. 1, 2, 3, 7
B. 2, 3, 4, 5
C. 3, 5, 6, 7
A
183
8921
How are generators rated?
A. Watts at rated voltage
B. Amperes at rated voltage
C. The impedance at rated voltage
B
184
8925
The generator rating is usually found stamped on the:
A. Firewall
B. Generator
C. Engine
B
185
What does a regulator do?
Varies the strength of the magnetic field in a generator.
186
What is residual voltage?
Result of magnetism in the field shoes
187
If the positive field lead between the generator and a generator controlled panel breaks (no generator field current) and is shorted while the engine is running, a voltmeter connected to the generator output would indicate what?
residual voltage
188
How can the direction rotation of a DC motor be changed?
By reversing the electrical connections to either the field or armature windings
189
What are the pole pieces or shoes used in an DC generator?
Part of the field assembly
190
Why are the poles in a generator laminated?
To reduce eddy current losses
191
What is a method used to restore generator field residual magnetism?
Flash the fields
192
8803
Some electric motors have 2 sets of ield windings wound in opposite directions so that the:
A. Speed of the motor can be more closely controlled.
B. Power output of the motor can be more closely controlled
C. Motor can be operated in either direction.
C
193
8813
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
B. Number of conductors in the armature
C. Speed at which the armature rotates
A
194
8814
The pole pieces or shoes used in a DC generator are a part of the:
A. armature assembly
B. Field assembly
C. Brush assembly
B
195
8897
If the positive field lead between a generator and a generator control panel breaks and is shorted while the engine is running, a voltemter connected to generator output would indicate:
A. Zero voltage
B. Residual voltage
C. Normal voltage
B
196
8898
What is a method used for restoring generator field residual magnetism?
A. Flash the fields
B. Reseat the brushes
C. Energize the armature
A
197
8912
How can the direction of rotation of a DC electric motor be changed?
A. Interchange the wires which connect the motor to the external power source.
B. Reverse the electrical connections to either the field or armature windings.
C. Rotate the positive brush one commutator segment.
B
198
8923
The poles of a generator are laminated to:
A. Reduce flux losses
B. Increase flux concentration
C. Reduce eddy current losses
C
199
8926
Residual voltage is a result of magnetism in the:
A. Field windings
B. Field shoes
C. Armature
B
200
Brush arcing is low in a generator due to ____?
low spring tension
201
What does the brush pigtail do?
eliminates sparking to brush guides
202
What is the purpose of a commutator in a DC motor?
reverses the current in the coil when the coil becomes parallel to the lines of force.
## Footnote
creates constant DC current to keep it from being AC
203
What is the MICA insulation between the commutator bars of a DC generator and how much should they be undercut?
equal to the width of the MICA
204
8808
What is a cause of generator brush arcing?
A. Seating brushes with No 000 sandpaper
B. Carbon dust particles
C. Low spring tension
C
205
8818
In a generator, what eliminates any possible sparking to the brush guides caused by th emovement of the brushes within the holder?
A. The brush pigtail
B. Brush spring tension
C. Undercutting the mica on the commutator
A
206
8822
The commutator of a generator:
A. Changes direct current produced in the armature into alternatirng current as it is taken from the armature.
B. Changes alternating current produced in the armature into direct current as it is taken from the armature.
C. Reverses the current in the field coils at the proper time in order to produce direct current.
B
207
8827
To what depth is the mica insulation between the commutator bars of a DC generator undercut?
A. 1/2 the width of the mica
B. Equal to twice the width of the mica
C. Equal to the widthof the mica
C
208
What are the 3 basic types of DC motors?
1. Series wound
2. Shunt wound
3. Compound wound
209
What type of generator is not used as an airplane generator?
Series wound
210
What is characteristic of a series wound motor?
field windings are connected in series with the armature winding
211
A series wound DC motor will require ____ (more / less) current at low RPM than high RPM?
more
212
The starting current of a series wound DC motor produces _____.
high starting torque
213
What kind of motor is used for landing gear?
split field series-wound
214
How does the current flow in a Shunt wound motor?
in parallel between the armature and the fields
215
How is a shunt wound DC generator connected?
by shunting both fields across the armature
216
What is a compound wound generator?
combination of series wound and shunt wound windings
217
How do you regulate the voltage output of a compound wound DC generator?
Vary the current flowing through the shunt field coils
218
8373
An electric motor used to raise and lower a landing gear would most likely be a:
A. Shunt field series-wound motor
B. Split field shund-wound motor
C. Split field series-wound motor
C
219
8806
What is the principal advantage of the series-wound DC motor?
A. High starting torque
B. Suitable for constant speed use
C. Low starting torque
A
220
8810
The starting current of a series-wound DC motor, in passing through both the field and armature windings, produces a:
A. Low starting torque
B. speed slightly higher when unloaded
C. high starting torque
C
221
8819
A series-wound Dc electric motor will normally require:
A. more current at high RPM than at low RPM
B. approximately the same current throughout its operating range of speed.
C. more current at low RPM than at high RPM
C
222
8829
Which type of DC generator is not used as an airplane generator?
A. Externally grounded
B. series wound
C. compound wound
B
223
8839
1. There are 3 basic types of DC motors; series, shunt, and compound
2. In the series motor, the field windings, consisting of relatively few turns of heavy wire, are connected in series with the armature winding.
Regarding the above statements:
A. Only #1 is true
B. Only #2 is true
C. Both #1 and #2 are true
C
224
8908
The most common method of regulating the voltage output of a compound DC generator is to very the:
A. current flow through the shunt field coils.
B. Total effective field strength by changing the reluctance of the magnetic circuit.
C. Resistance of the series field circuit.
A
225
8922
How is a shunt-wound DC generator connected?
A. one field is shunted across the other.
B. both fields are shunted across the armature
C. The field and armature are shunted with a capacitor
B
226
What is armature reaction?
Shifting of the magnetic field in the generator motor due to a field set up by the armatur itself.
227
What is the effect of armature reaction?
Proportional to the load on the generator
228
What is the purpose of interpoles?
To overcome the effect of armature reaction
229
What is NOT one of the purposes of the interpoles in a generator?
Reducing field strength
230
How does a voltage regulator control generator output voltage?
by changing the resistance of the generator field circuit which varies the current flow to the generator field coil.
231
On a vibrator-type voltage regulator the actual time the points remain open depends on _____.
the load carried by the generator
232
If a short occurs between the positive armature lead and the field lead of a shunt generator which has the voltage regulator on the positive side of the field circuit the generator voltage will _____.
increase
233
If the reverse current cutout relay contact fails to open after the generator output has dropped below battery potential, what will happen?
current will flow through the generator armature opposite the normal direction and through the shunt field in the normal direction.
(converts the generator into a motor.)
234
How does the overvoltage control automatically protect the generator system?
By opening the shunt field circuit controlling the voltage of the generator.
235
What is the most likely cause if any one generator shows low voltage on a twin engine aircraft?
out-of-adjustment voltage regulator
236
8807
If a generator is equipped with a vibrator-type voltage regulator, the actual time the voltage regulator points remain open.
A. Depends on the load carried by the generator.
B. Is controlled by the reverse-current cutout relay point clearance.
C. Is increased when the external load is greater than the generator output.
A
237
8812
The method most often used in overcoming the effect of armature reaction is through the use of:
A. interpoles
B. shaded poles
C. drum-wound armatures in combination with a negatively connected series field.
A
238
8816
If the reverse current cutout relay contact points fail to open after the generator output has dropped below battery potential, current will flow through the generator armature.
A. In the normal direction and through the shunt field opposite the normal direction.
B. And the shunt field opposite the normal direction.
C. Opposite the normal direction and through the shunt field in the normal direction.
C
239
8824
Which of the following is not one of the purposes of interpoles in a generator?
A. Reduce field strength
B. Overcome armature reaction
C. Reduce arcing at the brushes
A
240
8828
A voltage regulator controls generator output by:
A. introducing a resistance in generator-to-batteyr lead in the event of overload.
B. shorting out field coil in the event of overload.
C. varying current flow to generator field coil.
C
241
8904
A voltage regulator controls generator voltage by changing the:
A. resistance in the generator output circuit
B. current in the generator output circuit
C. resistance of the generator field circuit
C
242
8905
The overvoltage control automatically protects the generator system when excessive voltage is present by:
A. opening the shunt field circuit
B. Opening and resetting the field control relay
C. breaking a circuit to the trip coil of the field control relay.
A
243
8911
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
B. shorted or grounded wiring
C. a defective reverse current cutout relay
A
244
What does an equalizer circuit do?
assure that all generators share the load equally
245
How does an equalizer operate?
increasing the output of low generator & decreasing the output of the high generator.
246
The frequency of an alternator is dependant on _____.
RPM
247
When AC generators are operated in parallel what must happen to frequency and voltage?
They must both be equal
248
2 Types of AC motors used in aircraft.
1. Induction
2. Synchronous
249
How many cycles are produced by a 6 pole alternator of the revolving field type for each revolution of the rotor?
3
250
How is voltage output of an alternator regulated?
by controlling the voltage output of the DC exciter
251
How is a DC battery charged with an AC alternator?
by a transformer and rectifier
252
How do you cool a starter generator during ground operation?
By an integral fan
253
8809
When AC generators are operated in parallel, the:
A. amperes and frequency must both be equal
B. frequency and voltage must both be equal
C. amperes and voltage must both be equal
B
254
8815
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. 4
B. 3
C. 6
B
255
8831
During ground operation, aircraft generator cooling is usually. accomplished by:
A. Auxiliary air cooled through an air/fuel heat exchanger
B. An integral fan
C. An external motor-driven fan
B
256
8849
The voltage output of an alternator may be regulated by controlling the:
A. speed of the alternator
B. voltage output of the DC exciter
C. resistance in the rotor windings
B
257
8906
When DC generators are operated in parallel to supply power for a single load, their controls include an equalizer circuit to assure that all generators share the load equally. The equalizer circuit operates by:
A. Increasing the output of the low generator to equal the outpot of the high generator.
B. Decreasing the output of the high generator to equal the output of the low generator.
C. Increasing the output of the low generator and decreasing the output of the high generator until they are equal.
C
258
8913
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 stepdown transformer and a rectifier
B. an inverter and a voltage-dropping resistor
C. a dynamotor with a half-wave DC output
A
259
8924
What is the frequency of an alternator dependent upon?
A. Voltage
B. RPM
C. Current
RPM
260
How does an AC Generator provide a stable AC generator frequency?
Through a governor controlled variable delivery hydraulic pump and a hydralic motor to maintain a constant output RPM
261
How is a constant speed drive cooled?
by oil spray
262
How is a Constant Speed Drive (CSD) disconnected in the event of overheating?
Can it be reconnected?
switch in the cockpit.
Can only be reconnected on the ground.
263
What does an integrated drive generator (IDG) do?
Combines the CSD and generator into a single package.
264
How does an IDG produce current?
With a high output AC generator and brushless system
265
What must be done if the IDG is contaminated?
Must be replaced
266
8928
CSD driven generators are usually cooled by:
A. oil spray
B. an integral fan
C. both ram air and an integral fan
A
267
8929
A CSD unit drives a generator through the use of:
A. a synchronous electric motor
B. An infinitely variable mechanical gearing system
C. A variable hydraulic pump and hydraulic motor
C
268
8930
Integrated drive generator must be replaced if:
A. the KVA has been exceeded by 10%
B. The unit has an overspeed of 10% of its design operational speed.
C. The pressure differential button is extended.
C
269
8931
If the IDG scavenge oil filter is contaminated with chunks or pieces of metal:
A. change the oil at 25 hour intervals
B. Remove and replace the IDG
C. Replace the oil and filter at 25 hour intervals
B
270
8932
When necessary during opertion, CDS disconnect is usually accomplished by:
A. A switch in the cockpit
B. Circuit breaker activation
C. A shear section in the input shaft
A
271
8933
A CSD unit that is disconnected in flight, due to a malfunction such as overtemperature, may be reconnected:
A. Automatically if the temperature falls back into the normal operating range.
B. Manually by the flightcrew
C. Only on the ground by maintenance personnel.
C
272
9030
Integrated drive generators (IDG) emply a type of high output AC generator that utilizes:
A. brushes and slip rings to carry generated DC exciter current to the rotating field.
B. Battery current to excite the field.
C. A brushless system to produce current.
C
273
10068
Which circuit is used to control electrical power between the aircraft and generator and the distribution bus?
A. Generator Circuit
B. Alternator Circuit
C. Split-parallel System
A
274
10069
What is the aircraft battery used for?
A. Emergency power
B. Emergency power and engine starting
C. continued operation
B
275
10070
Which statement is true concerning power distribution on multiengine aircraft?
A. Power distribution systems on modern multiengine aircraft contain a single bus to supply power.
B. Dual-feed buses receive power from one generator bus, either the left or right bus.
C. Critical electrical loads are supplied from more than one bus.
C
276
10071
What is an advantage of a parallel system?
A. Simpler design
B. In the event of a generator failure, the buses are already connected and the defective generator need only be isolated from the system.
C. Maintenance requirements for parallel systems are less than split-bus systems.
B
277
What does a rectifier do?
Converts AC current into DC.
278
What does an inverter do?
Provides Alternating current from battery-generator (DC) systems
279
What is the inductor inverter controlled by?
DC stator field current
280
8294
When overhauling electrical equipment, all necessary information should be obtained from:
A. Aircraft maintenance manual
B. Maintenance instructions published by the aircraft and / or equipment.
C. Illustrated parts manual for the aircraft.
B
281
8832
What does a rectifier do?
A. Changes direct current into alternating current
B. Changes alternating current into direct current
C. Reduces voltage
B
282
8895
Certain transport aircrart use AC electrical power for all normal operation and battery furnished DC electrical power for standby emergency use. In aircraft of this type that operate no DC generatros, the batteries are kept charged by:
A. inverters which use the aircraft's AC generators as a source of power.
B. Alternators which use the aircraft's generators as a source of power.
C. Rectifiers which use the aircraft's AC generators as a source of power.
C
283
8901
The inductor-type inverter output voltage is controlled by the:
A. number of poles and speed of the motor.
B. voltage regulator
C. DC stator field current
C
284
8915
Major adjustments on equipment such as regulators, contactors, and inverters are best accomplished outside the airplane on test benches with necessary instruments and equipment. Adjustement procedure should be as outlined by:
A. the equipment manufacturer
B. FAA
C. aircraft technical orders
A
285
8916
A battery-generator system provides direct current. On installations requiring alternating current from the battery-generator system, it is necessary to have:
A. transformer
B. inverter
C. variable resistor between the battery and generator
B
286
8918
The purpose of a rectifier in an electrical system is to change:
A. frequency of alternating current
B. direct current ot alternating current
C. Alternating current to direct current
C
287
Position lights much meet what minimum requirements?
Specified by the FARs
288
If one switch controls all navigation lights, how are they connected?
* Parrallel to each other
* In series with the switch
289
How should the anti-collision light be installed?
independently of the NAV lights
290
A landing light is an intermittent duty circuit.
What is the maximum amount of time a circuit can be in operation and still be considered an intermittent duty circuit?
2 minutes or less
291
8826
What is the color and orientation of the position lights for navigation on civil airplane?
A. Left side - green, right side - red, rear aft - white
B. Left side - red, right side - green, rear aft - white
C. Left side - white, right side - green, rear aft - red
B
292
8856
If one switch is used to control all navigation lights, the lights are most likely connected:
A. in series with each other and parallel to the switch
B. in series with each other and in series with the switch
C. Parallel to each other and in series with the switch
C
293
8900
Which of the following must be accomplished when installing an anticollision light?
A. Install a switch independent of the position light switch
B. Use shielded electrical cable ot assure fail safe operation
C. Connect the anticollision light to the aircraft postition light switch
A
294
8907
What is the maximum amount of time a circuit can be in operation and still be an intermittent duty circuit?
A. 3 minutes
B. 2 minutes
C. 1 minute
B
295
8914
During inspection of an anticollision light installation for condition and proper opertion, it should be determined that:
A. Electrical or mechanical interconnections are provided so that the anticollision light will operate at all times that the position light switch is in the ON position.
B. An appropriately rated fuse is in position at the light to protect the connecting wiring against electrical faults.
C. The anticollision light can be operated independently of the position lights.
C
296
8910
Upon completion of the landing gear extension cycle, the green light illuminated and the red light remained lit. What is the probably cause?
A. short in the down limit switch
B. short in the gear safety switch
C. short in the up limit switch
C
297
298
8951
What is the indication of the red landing gear position light under the following conditions?
Aircraft on jacks
Landing gear in transit
Warning horn sounding
A. extinguished
B. flashing
C. illuminated
A
299
8952
Which repair should be made if the gear switch was placed in the UP position and the gear does not retract?
A. Replace wire #15
B. Replace the down limit switch
C. Replace wire #12
C
300
8954
What will illuminate the amber indicator light?
A. Closing the nosewheel gear full retract switch.
B. Retarding 1 throttle and closing the left wheel gear locked down switch.
C. Closing the nose, left and right wheel gear full retract switches.
C
301
8955
What is the minimum circumstance that will cause the landing gear warning horn to indicate an unsafe condition?
A. All gears up and 1 throttle retarded
B. Any gear up and both throttles retarded
C. Any gear not down and locked, and 1 throttle retarded
C
302
10072
What are 2 types of soldering?
A. soft soldering and hard soldering
B. Brazing and soft soldering
C. welding and tacking
B
303
