2A672 EOC Practice Test

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| By A1c2a652

A1c2a652

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Quizzes Created: 1 | Total Attempts: 374

Questions: 90 | Attempts: 374 | Updated: Mar 22, 2023

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Questions and Answers

1.

When there are 8 electrons in the outer most shell of an atom, it is considered
- A.
  
  Complete
- B.
  
  Unstable
- C.
  
  Charged
- D.
  
  Stable
Correct Answer
D. Stable

Explanation
When an atom has 8 electrons in its outermost shell, it is considered stable. This is because the outermost shell, also known as the valence shell, is fully filled with electrons. According to the octet rule, atoms tend to gain, lose, or share electrons in order to achieve a stable configuration with 8 electrons in the valence shell. Therefore, having 8 electrons in the outermost shell indicates that the atom has achieved a stable electron configuration, making it stable.

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2.

In an atom, this electron contains the most energy.
- A.
  
  Stationary electrons
- B.
  
  Orbiting electrons
- C.
  
  Valence electrons
- D.
  
  K shell electrons
Correct Answer
C. Valence electrons

Explanation
Valence electrons are the electrons located in the outermost energy level of an atom. These electrons have the highest energy because they are farthest from the positively charged nucleus and experience less attraction. Valence electrons play a crucial role in chemical bonding and determining the reactivity of an element.

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3.

Atoms having more than 4 electrons, but less than 8 are known as
- A.
  
  Insulators
- B.
  
  Conductors
- C.
  
  Stable atoms
- D.
  
  Semiconductors
Correct Answer
A. Insulators

Explanation
Atoms having more than 4 electrons, but less than 8 are known as insulators. This is because insulators have a completely filled valence shell, which makes it difficult for electrons to move freely and conduct electricity. The outermost shell of these atoms is almost full, so they do not readily gain or lose electrons to form ions. Instead, they hold onto their electrons tightly, preventing the flow of electric current.

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4.

The electrostatic fields around a positive ion move
- A.
  
  Inward
- B.
  
  Outward
- C.
  
  Inward, then outward
- D.
  
  Outward, then inward
Correct Answer
B. Outward

Explanation
The electrostatic fields around a positive ion move outward. This is because positive ions have a surplus of protons, which creates an imbalance of positive charge. As a result, the positive charge is repelled and spreads outwards, creating an electrostatic field that extends away from the ion.

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5.

These factors affect the resistance of a material.
- A.
  
  Area, weight, and state of material
- B.
  
  Area, temperature, and type of material
- C.
  
  Temperature, weight, and state of material
- D.
  
  Temperature, type of material, and state of material
Correct Answer
B. Area, temperature, and type of material

Explanation
The resistance of a material is influenced by its area, temperature, and type of material. The area of a material affects its resistance because a larger area provides more paths for the current to flow, resulting in lower resistance. Temperature also affects resistance as an increase in temperature leads to an increase in resistance due to the increased collisions between the atoms or molecules in the material. Additionally, the type of material determines its resistivity, which is a measure of how strongly it resists the flow of electric current.

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6.

In a series-parallel circuit, the series current at I1 = 9 amps; in two parallel branches, I2 = 5 amps; and the value of I3 is not listed. Use Ohm's law to find the value of I3 and IT.
- A.
  
  I3 = 5 amps and IT = 14 amps
- B.
  
  I3 = 4 amps and IT = 9 amps
- C.
  
  I3 = 4 amps and IT = 18 amps
- D.
  
  Not enough information to solve
Correct Answer
B. I3 = 4 amps and IT = 9 amps

Explanation
In a series-parallel circuit, the total current (IT) is equal to the sum of the currents in the series branches. Since I1 = 9 amps and I2 = 5 amps, the total current IT can be calculated as 9 + 5 = 14 amps.

Since I3 is not listed, we need to use Ohm's law to find its value. In a parallel circuit, the voltage across each branch is the same. Therefore, we can use the current in one branch (I2 = 5 amps) and the total resistance of the parallel branches to find the voltage. Once we have the voltage, we can use Ohm's law again to find I3.

Since the question does not provide any information about the resistance values, we cannot calculate the value of I3. Therefore, the answer is "not enough information to solve".

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7.

This is relative motion between a conductor and a magnetic field that causes voltage to be induced.
- A.
  
  Magnetism
- B.
  
  Reluctance
- C.
  
  Direct current
- D.
  
  Electromagnetic induction
Correct Answer
D. Electromagnetic induction

Explanation
Electromagnetic induction is the process in which a voltage is induced in a conductor when it is moved relative to a magnetic field. This phenomenon is based on Faraday's law of electromagnetic induction, which states that a changing magnetic field induces an electric current in a conductor. Therefore, when there is relative motion between a conductor and a magnetic field, voltage is induced in the conductor through electromagnetic induction.

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8.

This is the basic principle of transformer operation.
- A.
  
  Mutual induction
- B.
  
  Magnetic induction
- C.
  
  Counter electromotive force
- D.
  
  Primary and secondary induction
Correct Answer
A. Mutual induction

Explanation
Mutual induction is the correct answer because it refers to the process by which a changing current in one coil induces a voltage in another coil that is in close proximity. This is the fundamental principle behind the operation of a transformer, where two coils are magnetically coupled and the voltage is transformed from one coil to another. Mutual induction allows for efficient transfer of electrical energy between the primary and secondary coils of a transformer.

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9.

This transformer winding acts as a conductor and provides the path for the voltage to be induced into.
- A.
  
  Field
- B.
  
  Primary
- C.
  
  Secondary
- D.
  
  Stationary
Correct Answer
C. Secondary

Explanation
The secondary winding of a transformer is responsible for transferring the induced voltage from the primary winding to the load. It acts as a conductor and provides the path for the voltage to be induced into. The primary winding, on the other hand, is connected to the power source and is responsible for creating the magnetic field that induces the voltage in the secondary winding. The stationary option does not make sense in this context as it does not describe the function of the winding. Therefore, the correct answer is secondary.

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10.

If the size of the plates of a capacitor is increased, how is capacitance affected?
- A.
  
  Capacitance increases
- B.
  
  Capacitance decreases
- C.
  
  Capacitance remains the same
- D.
  
  Capacitance increases only if the plate size doubles
Correct Answer
A. Capacitance increases

Explanation
When the size of the plates of a capacitor is increased, the distance between the plates decreases. This results in an increase in the capacitance of the capacitor. Capacitance is directly proportional to the surface area of the plates and inversely proportional to the distance between them. Therefore, when the plate size is increased, the capacitance increases.

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11.

This statement best describes a capacitive circuit.
- A.
  
  Current leads applied voltage by 90 degrees
- B.
  
  Applied voltage leads current by 90 degrees
- C.
  
  Has the ability to conduct in one direction and not the other
- D.
  
  Has the ability to conduct in all directions when gated or discharged
Correct Answer
A. Current leads applied voltage by 90 degrees

Explanation
A capacitive circuit is characterized by the fact that the current leads the applied voltage by 90 degrees. This means that the current reaches its peak value before the voltage does in a capacitive circuit. This behavior is due to the nature of capacitors, which store and release electrical energy in response to changes in voltage. As the voltage across a capacitor changes, the capacitor charges or discharges, causing the current to flow in the opposite direction. This phase shift of 90 degrees between current and voltage is a key characteristic of capacitive circuits.

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12.

This statement best describes a diode.
- A.
  
  It is a five-terminal device
- B.
  
  It is a three-terminal device
- C.
  
  It has the ability to conduct in one direction and not the other
- D.
  
  It has the ability to conduct in all directions when gated or discharged
Correct Answer
C. It has the ability to conduct in one direction and not the other

Explanation
A diode is a two-terminal device that allows current to flow in one direction and blocks it in the opposite direction. This property is known as rectification and is the main characteristic of a diode. It is commonly used in electronic circuits to convert alternating current (AC) to direct current (DC) by blocking the negative half of the AC waveform. Therefore, the statement "It has the ability to conduct in one direction and not the other" accurately describes a diode.

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13.

How many electrons does the valence band of an intrinsic semiconductor have?
- A.
  
  3
- B.
  
  4
- C.
  
  5
- D.
  
  6
Correct Answer
B. 4

Explanation
The valence band of an intrinsic semiconductor has 4 electrons. In an intrinsic semiconductor, the valence band is fully occupied by electrons at absolute zero temperature. The valence band represents the highest energy level that electrons can occupy in the valence shell of an atom. Since the valence band can accommodate a maximum of 8 electrons, and an intrinsic semiconductor is typically made up of atoms with 4 valence electrons, it means that each atom contributes 1 electron to the valence band, resulting in a total of 4 electrons.

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14.

This is the area of a semiconductor where P-type material is joined to N-type material.
- A.
  
  Dielectric region
- B.
  
  Depletion region
- C.
  
  Depletion field
- D.
  
  PN region
Correct Answer
B. Depletion region

Explanation
The correct answer is depletion region. In a semiconductor, the depletion region is formed when P-type material is joined to N-type material. This region is depleted of majority carriers and contains immobile ions. It acts as a barrier to the flow of current under reverse bias conditions and plays a crucial role in the operation of diodes and other semiconductor devices.

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15.

A bridge rectifier is installed in an alternating current (AC) circuit to
- A.
  
  Decrease direct current (DC) pulses
- B.
  
  Provide fullwave rectification
- C.
  
  Provide halfwave rectification
- D.
  
  Decrease ripple frequency
Correct Answer
B. Provide fullwave rectification

Explanation
A bridge rectifier is installed in an alternating current (AC) circuit to provide fullwave rectification. This means that it converts the AC voltage into a pulsating DC voltage that flows in the same direction. The bridge rectifier uses four diodes arranged in a bridge configuration to rectify both the positive and negative halves of the AC cycle, resulting in a smoother and more continuous output. This is different from halfwave rectification, where only one half of the AC cycle is rectified. Providing fullwave rectification allows for a more efficient conversion of AC to DC power.

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16.

In a circuit using a bridge rectifier, how many diodes are forward biased during the first cycle of alternating current (AC)?
- A.
  
  4
- B.
  
  3
- C.
  
  2
- D.
  
  1
Correct Answer
C. 2

Explanation
During the first cycle of alternating current (AC) in a circuit using a bridge rectifier, two diodes are forward biased. A bridge rectifier consists of four diodes arranged in a bridge configuration. During the positive half cycle of AC, two diodes conduct and become forward biased, allowing the current to flow through them. The other two diodes remain reverse biased and do not conduct. Therefore, the correct answer is 2.

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17.

This is how a zener diode is connected in a solid state circuit to regulate voltage.
- A.
  
  In parallel to the load
- B.
  
  In series with the load
- C.
  
  In parallel to the resistor
- D.
  
  In series with the resistor
Correct Answer
A. In parallel to the load

Explanation
A zener diode is connected in parallel to the load in a solid-state circuit to regulate voltage. When connected in parallel, the zener diode acts as a voltage regulator by maintaining a constant voltage across the load. It achieves this by allowing current to flow through it in the reverse direction when the voltage exceeds its breakdown voltage. This ensures that the voltage across the load remains constant, regardless of any variations in the input voltage. Connecting the zener diode in series with the load or resistor would not provide the desired voltage regulation.

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18.

This is how a zener diode is connected in a circuit to protect the load.
- A.
  
  In parallel to the resistor
- B.
  
  In series with the load
- C.
  
  In parallel to the load
- D.
  
  Forward biased
Correct Answer
C. In parallel to the load

Explanation
A zener diode is connected in parallel to the load in order to protect it. When the voltage across the load exceeds the breakdown voltage of the zener diode, it starts conducting and limits the voltage across the load to the breakdown voltage. This ensures that the load is protected from excessive voltage and prevents any damage to it.

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19.

A silicon-controlled rectifier (SCR) has this many layers.
- A.
  
  1
- B.
  
  2
- C.
  
  3
- D.
  
  4
Correct Answer
D. 4

Explanation
An SCR, also known as a thyristor, is a four-layer semiconductor device that acts as a switch. It consists of three P-N junctions and four layers of alternating P and N type materials. The four layers are the anode, cathode, P-type layer, and N-type layer. When a voltage is applied to the gate terminal, it triggers the SCR to conduct current from the anode to the cathode. Therefore, the correct answer is 4 layers.

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20.

In order to turn off a silicon-controlled rectifier (SCR), the current must drop below the
- A.
  
  Trigger current
- B.
  
  Holding current
- C.
  
  Variable current
- D.
  
  Breakdown current
Correct Answer
B. Holding current

Explanation
To turn off a silicon-controlled rectifier (SCR), the current must drop below the holding current. The holding current is the minimum current required to maintain the SCR in the on-state once it has been triggered. If the current drops below this threshold, the SCR will turn off and stop conducting current. The trigger current, on the other hand, is the minimum current required to initially turn on the SCR. Variable current and breakdown current are not relevant to turning off the SCR.

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21.

This is the major difference between a NPN and PNP transistor.
- A.
  
  A PNP transistor can only be used as a regulator
- B.
  
  An NPN transistor can only be used as a switch
- C.
  
  Direction of current flow
- D.
  
  Number of junctions
Correct Answer
C. Direction of current flow

Explanation
The major difference between a NPN and PNP transistor is the direction of current flow. In an NPN transistor, the current flows from the collector to the emitter, while in a PNP transistor, the current flows from the emitter to the collector. This difference in current flow direction determines the applications and functions of the transistors.

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22.

If the arrow in a bipolar transistor is pointing away from the base, which type of transistor is it?
- A.
  
  N-type
- B.
  
  P-type
- C.
  
  NPN
- D.
  
  PNP
Correct Answer
C. NPN

Explanation
If the arrow in a bipolar transistor is pointing away from the base, it indicates that the transistor is an NPN type. In an NPN transistor, the majority charge carriers are negative electrons, and the arrow represents the direction of the conventional current flow. The base region is P-type, and the emitter and collector regions are N-type.

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23.

This is the circuit in a bipolar transistor that carries 5 percent of the current flow.
- A.
  
  Base circuit
- B.
  
  Load circuit
- C.
  
  Control circuit
- D.
  
  Emitter-controller circuit
Correct Answer
C. Control circuit

Explanation
The correct answer is "control circuit". In a bipolar transistor, the control circuit is responsible for regulating the flow of current. It determines the amount of current that flows through the transistor by adjusting the voltage at the base terminal. The control circuit acts as a switch, allowing or blocking current flow between the emitter and collector terminals. In this scenario, the circuit in question carries only 5 percent of the total current flow, suggesting that it is controlling the current rather than being the main circuit for carrying it.

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24.

This is the purpose of a transistor amplifier.
- A.
  
  Controls current to the load
- B.
  
  Controls voltage to the load
- C.
  
  Controls resistance to the load
- D.
  
  Acts as a spike protector for the load
Correct Answer
A. Controls current to the load

Explanation
A transistor amplifier is designed to control the current flowing to the load. By varying the input signal, the transistor can regulate the amount of current that passes through it, thereby controlling the current to the load. This allows the amplifier to amplify or attenuate the signal as desired, providing the necessary current amplification to drive the load effectively.

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25.

These are the three leads of a unijunction transistor (UJT).
- A.
  
  Anode, cathode, and gate
- B.
  
  Emitter, base 1, and base 2
- C.
  
  Emitter, collector, and base
- D.
  
  Common emitter, common collector, and common base
Correct Answer
B. Emitter, base 1, and base 2

Explanation
The correct answer is emitter, base 1, and base 2. In a unijunction transistor (UJT), the emitter is the terminal through which the majority carriers (electrons) enter the device. Base 1 and base 2 are the two terminals that control the flow of current between the emitter and the other two terminals. The UJT operates by varying the resistance between base 1 and base 2, which in turn controls the current flow through the emitter.

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26.

The emitter in a unijunction transistor always points toward the
- A.
  
  Base 1 lead
- B.
  
  Collector
- C.
  
  Emitter
- D.
  
  Gate
Correct Answer
A. Base 1 lead

Explanation
In a unijunction transistor, the emitter is always connected to the base 1 lead. This is because the base 1 lead is responsible for controlling the flow of current in the transistor. By connecting the emitter to the base 1 lead, the transistor can regulate the current effectively. The collector, on the other hand, is responsible for collecting the current that flows through the transistor, while the gate is not applicable in a unijunction transistor. Therefore, the emitter always points towards the base 1 lead.

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27.

This controls the firing time of the unijunction transistor (UJT).
- A.
  
  Intrinsic standoff ratio
- B.
  
  Resistance in the circuit
- C.
  
  Capacitance in the circuit
- D.
  
  Resistance and capacitance in the circuit
Correct Answer
D. Resistance and capacitance in the circuit

Explanation
The firing time of the unijunction transistor (UJT) is controlled by the resistance and capacitance in the circuit. The resistance determines the rate at which the capacitor charges and discharges, while the capacitance determines the amount of time it takes for the capacitor to reach its threshold voltage. By adjusting the values of resistance and capacitance, the firing time of the UJT can be precisely controlled.

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28.

How many semiconductors make up a metal oxide varistor?
- A.
  
  2
- B.
  
  3
- C.
  
  4
- D.
  
  5
Correct Answer
A. 2

Explanation
A metal oxide varistor is made up of two semiconductors. These semiconductors are usually made of zinc oxide and are connected in parallel. When a voltage is applied to the varistor, the resistance of the semiconductors decreases, allowing the varistor to conduct electricity and protect against overvoltage. Therefore, the correct answer is 2.

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29.

This component of the voltage regulator compensates for losses in the power cable by sensing changes in current flow.
- A.
  
  Load rheostat
- B.
  
  No load rheostat
- C.
  
  Line drop switch
- D.
  
  Voltage adjustment rheostat
Correct Answer
A. Load rheostat

Explanation
The load rheostat is the correct answer because it compensates for losses in the power cable by sensing changes in current flow. It helps regulate the voltage by adjusting the resistance in the circuit, which in turn helps maintain a stable voltage level despite any losses in the power cable.

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30.

Refer to foldout 1. After performing an operational check of the -86, you proceed to shut the unit down. After the generator stops, you notice the engine ON light continues to be illuminated. Which is a probable cause of this trouble?
- A.
  
  S46 open
- B.
  
  S48 open
- C.
  
  S46 closed
- D.
  
  S48 closed
Correct Answer
D. S48 closed

Explanation
The probable cause of the engine ON light continuing to be illuminated after shutting down the generator is that S48 is closed. This suggests that there is a fault or malfunction in the circuitry or wiring associated with S48, which is preventing it from opening and interrupting the flow of electricity to the engine ON light.

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31.

Refer to foldout 1. During operation of the -86, you get no response when you place S13 in the GENERATE position. A check for voltage at J8, terminal N, shows 12 VDC. Which is the probable cause of this trouble?
- A.
  
  M4 is open
- B.
  
  S53 is open
- C.
  
  S46 is open
- D.
  
  K16 is open
Correct Answer
B. S53 is open

Explanation
The probable cause of the trouble is that S53 is open. This means that the switch S53, which is responsible for generating a response when placed in the GENERATE position, is not functioning properly. This could be due to a fault or damage in the switch, causing it to remain open and not allow the necessary response.

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32.

Refer to foldout 1. You are operating a -86 at governed speed, but voltage doesn't build up. Which is the probable cause of this trouble?
- A.
  
  S1 is in the automatic postition
- B.
  
  R61 is turned fully clockwise
- C.
  
  K16 contacts are closing
- D.
  
  K23 contacts are open
Correct Answer
D. K23 contacts are open

Explanation
The probable cause of the trouble is that the K23 contacts are open. This means that there is a break in the circuit, preventing the voltage from building up.

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33.

Refer to foldout 1. During an operational check of a -86, the shutdown solenoid energizes immediately after the engine run indicator illuminates. Which is a probable cause of this trouble?
- A.
  
  S48 open
- B.
  
  S46 open
- C.
  
  S49 shorted
- D.
  
  S22 stuck open
Correct Answer
C. S49 shorted

Explanation
The shutdown solenoid is responsible for shutting down the engine. In this scenario, the shutdown solenoid is energizing immediately after the engine run indicator illuminates. This indicates that there is a short circuit in the S49 component. A shorted S49 could be causing the solenoid to receive excessive power and activate prematurely.

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34.

Refer to foldout 1. During operation of a -86, the low coolant light (DS50) illuminates, but the generator set does not shut down. Which is a probable cause of this trouble?
- A.
  
  A2
- B.
  
  DS50
- C.
  
  S55 is closed
- D.
  
  S22 is closed
Correct Answer
A. A2

Explanation
The low coolant light (DS50) illuminating but the generator set not shutting down could be caused by a closed S55 or S22. The closed S55 indicates that the coolant level is low, triggering the low coolant light. However, the generator set does not shut down because S22, which is responsible for shutting down the generator set in case of low coolant, is closed as well. Therefore, even though the low coolant light is on, the generator set continues to operate.

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35.

Refer to foldout 1. Where is the best point to check voltage going to the -86 exciter field?
- A.
  
  J8, terminal D-F
- B.
  
  J8, terminal V-X
- C.
  
  VR1, terminal C-R
- D.
  
  Automatic-manual switch S1
Correct Answer
A. J8, terminal D-F

Explanation
The best point to check voltage going to the -86 exciter field is at J8, terminal D-F.

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36.

Refer to foldout 1. A -86 is operating and the AC voltmeter is reading 200 volts VAC on all three phases. Which do you do?
- A.
  
  Adjust VR1
- B.
  
  Adjust R61
- C.
  
  Adjust VR1 or R61
- D.
  
  Switch S15 to the L-N position
Correct Answer
D. Switch S15 to the L-N position

Explanation
Switching S15 to the L-N position will change the voltmeter from reading the voltage between phases to reading the voltage between line and neutral. This is necessary because the AC voltmeter is currently reading 200 volts VAC on all three phases, which indicates a problem with the voltage measurement. By switching S15 to the L-N position, the voltmeter will be able to accurately measure the voltage between line and neutral, providing a correct reading.

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37.

Refer to foldout 1. A -86 is sent to the shop on a Red X for "will not apply power to the aircraft". During the ops check, you place S5 in the closed position and the contactor light illuminates. When you release the switch, the contactor opens. Which is a probable cause of this trouble?
- A.
  
  S2 is open
- B.
  
  R46 is open
- C.
  
  K2 is closed
- D.
  
  K17 is closed
Correct Answer
B. R46 is open

Explanation
If R46 is open, it means that there is a break in the circuit. This would prevent the flow of current and cause the contactor to open when the switch is released. Therefore, R46 being open is a probable cause of the trouble described.

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38.

Refer to foldout 1. While operating a -86 at governed speed, you place S13 in the BUILD UP position and the UNDERVOLTAGE light comes on. Which is a probable cause of this trouble?
- A.
  
  Voltage regulator
- B.
  
  Plug interlock relay
- C.
  
  Memory time delay relay
- D.
  
  Overvoltage/undervoltage relay
Correct Answer
C. Memory time delay relay

Explanation
The probable cause of the trouble is the memory time delay relay. When the S13 switch is placed in the BUILD UP position, it triggers the memory time delay relay. However, in this scenario, the UNDERVOLTAGE light comes on, indicating that there might be an issue with the relay. The memory time delay relay is responsible for controlling the timing functions in the system, and if it malfunctions, it can cause the UNDERVOLTAGE light to come on.

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39.

Refer to foldout 1. The -86 is supplying 115 VAC to the aircraft and all of a sudden the AC contactor opens and there is no voltage indication on M2. Which is the probable cause of this trouble?
- A.
  
  Load contactor
- B.
  
  CR17 forward biased
- C.
  
  Overvoltage/undervoltage relay
- D.
  
  Memory time-delay relay energized
Correct Answer
D. Memory time-delay relay energized

Explanation
The probable cause of the trouble is that the memory time-delay relay is energized. This relay is responsible for introducing a time delay before allowing the AC contactor to close. If the relay is energized, it means that it is preventing the AC contactor from closing and supplying voltage to M2. This could be due to a malfunction or a fault in the relay, causing it to stay energized and not allowing the voltage to pass through.

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40.

Refer to foldout 1. You are driving on the flight line and notice a -86 with all the fault lights on. You try to reset S23, but the lights stay on. Which is a probable cause of this trouble?
- A.
  
  S30 is shorted
- B.
  
  S23 is stuck open
- C.
  
  K17 contacts are closed
- D.
  
  K23 contacts are closed
Correct Answer
A. S30 is shorted

Explanation
The probable cause of the trouble is that S30 is shorted. This means that there is a connection between the two terminals of S30, which is causing a fault in the system. This short circuit is preventing the reset of S23 from effectively turning off the fault lights.

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41.

When troubleshooting any electrical system, start by first finding the
- A.
  
  Common ground bus
- B.
  
  Main circuit breaker
- C.
  
  External power source
- D.
  
  Last known source of power
Correct Answer
D. Last known source of power

Explanation
When troubleshooting any electrical system, it is important to start by identifying the last known source of power. This means determining where the power was last flowing before the issue occurred. By doing this, one can narrow down the potential problem areas and focus their efforts on that specific section of the system. It helps in identifying any faults or disruptions in the power supply chain, which could be the cause of the problem.

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42.

To test the load contactor relay K1 using test probes, in which position must the automatic-manual voltage control switch be placed?
- A.
  
  AUTOMATIC
- B.
  
  MANUAL
- C.
  
  TEST
- D.
  
  OFF
Correct Answer
A. AUTOMATIC

Explanation
To test the load contactor relay K1 using test probes, the automatic-manual voltage control switch must be placed in the AUTOMATIC position. This is because the automatic position allows the relay to function based on the preset voltage control settings, enabling accurate testing of the load contactor relay. Placing the switch in any other position may disrupt the relay's operation or provide inaccurate results.

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43.

Which component on the B809 fuel system distributes and delivers an accurate amount of fuel to the engine cylinders?
- A.
  
  Injector pump
- B.
  
  Transfer pump
- C.
  
  Injector nozzles
- D.
  
  Throttle actuator
Correct Answer
A. Injector pump

Explanation
The injector pump is the component on the B809 fuel system that distributes and delivers an accurate amount of fuel to the engine cylinders. It is responsible for pressurizing the fuel and delivering it to the injectors at the correct time and in the correct quantity. The injector pump plays a crucial role in ensuring the engine receives the precise amount of fuel needed for optimal combustion and performance.

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44.

This B809 speed control system component produces a frequency pulse train for engine speed reference.
- A.
  
  Magnetic pick-up
- B.
  
  Engine speed governor
- C.
  
  Speed trim potentiometer
- D.
  
  Speed control potentiometer
Correct Answer
A. Magnetic pick-up

Explanation
The magnetic pick-up is a component of the B809 speed control system that generates a frequency pulse train. This pulse train is used as a reference for the engine speed. The magnetic pick-up detects the rotation of a gear or flywheel and converts it into an electrical signal, which is then used by the speed control system to regulate the engine speed.

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45.

Which contacts on the annunciator card of the B809 generator set control the AC input to the voltage regulator?
- A.
  
  Engine fault
- B.
  
  Regulator fault
- C.
  
  Generator fault
- D.
  
  Contactor fault
Correct Answer
C. Generator fault

Explanation
The contacts on the annunciator card of the B809 generator set that control the AC input to the voltage regulator are referred to as "generator fault." These contacts are responsible for indicating any faults or issues related to the generator, such as low voltage or overload conditions. By monitoring these contacts, the voltage regulator can receive the necessary input to regulate and control the AC input to the generator, ensuring proper functioning and protection of the system.

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46.

Which signal powers the regulator card output pulse sent to the exciter field of the B809?
- A.
  
  28.5 VDC
- B.
  
  110 VDC
- C.
  
  115 VAC
- D.
  
  200 VAC
Correct Answer
B. 110 VDC

Explanation
The regulator card output pulse sent to the exciter field of the B809 is powered by 110 VDC.

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47.

This action occurs when the B809 AC card senses an AC supply fault.
- A.
  
  Only generator output stops
- B.
  
  Only the AC contactor opens
- C.
  
  AC supply warning light illuminates
- D.
  
  AC contactor opens and generator output stops
Correct Answer
D. AC contactor opens and generator output stops

Explanation
When the B809 AC card senses an AC supply fault, it triggers the opening of the AC contactor and also stops the generator output. This means that both the AC contactor opens and the generator output stops simultaneously.

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48.

Refer to foldout 2. While operating a B809, which switch is closed to provide potential to the exciter field?
- A.
  
  S1, master switch
- B.
  
  S5, run/idle toggle switch
- C.
  
  S3, interlock toggle switch
- D.
  
  PB2, output control pushbutton switch
Correct Answer
B. S5, run/idle toggle switch

Explanation
The correct answer is S5, run/idle toggle switch. This switch is closed to provide potential to the exciter field while operating a B809.

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49.

Refer to foldout 2. During high voltage operation of the B809, what action occurs to prevent the DC contactors from closing?
- A.
  
  High sense relay (HSR) energizes
- B.
  
  Interlock (INT) relay energizes
- C.
  
  INT relay de-energizes
- D.
  
  HSR de-energizes
Correct Answer
D. HSR de-energizes

Explanation
During high voltage operation of the B809, the high sense relay (HSR) is energized. This means that the HSR is supplying power to a circuit or component. However, the question asks for an action that occurs to prevent the DC contactors from closing. If the HSR de-energizes, it means that the power supply to the circuit or component is cut off. Therefore, when the HSR de-energizes, it prevents the DC contactors from closing.

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50.

If there is a loss of residual magnetism in the exciter field poles
- A.
  
  Connect TB4-11 to 14 VDC power source
- B.
  
  Check the field transformer
- C.
  
  Field flash the generator
- D.
  
  Check the fault display
Correct Answer
C. Field flash the generator

Explanation
If there is a loss of residual magnetism in the exciter field poles, the generator can be field flashed to restore the magnetism. This can be done by connecting TB4-11 to a 14 VDC power source. It is important to check the field transformer and the fault display to identify any issues that may have caused the loss of residual magnetism.

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2A672 EOC Practice Test

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Refer to foldout 1. After performing an operational check of the -86, you proceed to shut the unit down. After the generator stops, you notice the engine ON light continues to be illuminated. Which is a probable cause of this trouble?

Refer to foldout 1. During operation of the -86, you get no response when you place S13 in the GENERATE position. A check for voltage at J8, terminal N, shows 12 VDC. Which is the probable cause of this trouble?

Refer to foldout 1. You are operating a -86 at governed speed, but voltage doesn't build up. Which is the probable cause of this trouble?

Refer to foldout 1. During an operational check of a -86, the shutdown solenoid energizes immediately after the engine run indicator illuminates. Which is a probable cause of this trouble?

Refer to foldout 1. During operation of a -86, the low coolant light (DS50) illuminates, but the generator set does not shut down. Which is a probable cause of this trouble?

Refer to foldout 1. Where is the best point to check voltage going to the -86 exciter field?

Refer to foldout 1. A -86 is operating and the AC voltmeter is reading 200 volts VAC on all three phases. Which do you do?

Refer to foldout 1. A -86 is sent to the shop on a Red X for "will not apply power to the aircraft". During the ops check, you place S5 in the closed position and the contactor light illuminates. When you release the switch, the contactor opens. Which is a probable cause of this trouble?

Refer to foldout 1. While operating a -86 at governed speed, you place S13 in the BUILD UP position and the UNDERVOLTAGE light comes on. Which is a probable cause of this trouble?

Refer to foldout 1. The -86 is supplying 115 VAC to the aircraft and all of a sudden the AC contactor opens and there is no voltage indication on M2. Which is the probable cause of this trouble?

Refer to foldout 1. You are driving on the flight line and notice a -86 with all the fault lights on. You try to reset S23, but the lights stay on. Which is a probable cause of this trouble?

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To test the load contactor relay K1 using test probes, in which position must the automatic-manual voltage control switch be placed?

Which component on the B809 fuel system distributes and delivers an accurate amount of fuel to the engine cylinders?

This B809 speed control system component produces a frequency pulse train for engine speed reference.

Which contacts on the annunciator card of the B809 generator set control the AC input to the voltage regulator?

Which signal powers the regulator card output pulse sent to the exciter field of the B809?

This action occurs when the B809 AC card senses an AC supply fault.

Refer to foldout 2. While operating a B809, which switch is closed to provide potential to the exciter field?

Refer to foldout 2. During high voltage operation of the B809, what action occurs to prevent the DC contactors from closing?

If there is a loss of residual magnetism in the exciter field poles