2A672 EOC Practice Test

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.

When the load time of -16 load bank is reached, the load is automatically removed and the cooling cycle begins. This indicates that the load bank is designed to operate within a specific time limit, and once that limit is reached, it initiates the cooling process to prevent overheating or any potential damage. The load test will not start over again, the load bank will not automatically shut down, and the display will not show the results of the load test.

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.

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.

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.

The deswirl ring on a gas turbine compressor is designed to smooth turbulent air flow. Turbulence in the air flow can cause inefficiencies and reduce the overall performance of the compressor. The deswirl ring helps to eliminate or reduce turbulence by redirecting and controlling the flow of air, resulting in a smoother and more efficient airflow. This allows for better compression of the air and improves the overall performance of the gas turbine compressor.

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.

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.

The given correct answer, "turbine start," suggests that the switch on the -95 is responsible for initiating the automatic starting cycle of the turbine. This switch likely activates the necessary mechanisms and processes that are required to start the turbine.

The -16 load bank is designed to test both alternating current (AC) and direct current (DC) loads. It is capable of simulating various electrical loads to assess the performance and capacity of power systems that utilize both AC and DC currents. Additionally, the load bank can also be used to test generator exciters, which are responsible for providing the necessary current to the generator field winding.

The air inlets on the EPU-6/E frequency converter need to be inspected prior to use to ensure that they are not blocked. If the air inlets are blocked, it can restrict the airflow and cause overheating of the converter, potentially leading to damage or malfunction. Inspecting the air inlets for blockage is important to ensure proper ventilation and efficient operation of the frequency converter.

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.

The torsion shaft is designed to break if the engine locks up in order to protect the rest of the engine components from damage. When the engine locks up, it creates a sudden increase in torque and rotational force. The torsion shaft is designed to absorb and distribute this force, but if it exceeds a certain threshold, the shaft will break. This prevents further damage to the engine and allows for a controlled shutdown.

The correct answer is air separator membranes (ASM). Air separator membranes are components that are used to separate nitrogen from oxygen in a nitrogen generator system. These membranes selectively allow oxygen molecules to pass through while blocking nitrogen molecules, resulting in the production of nitrogen gas. This process is based on the principle of selective permeation, where the membrane material allows for the separation of different gases based on their molecular size and properties. Therefore, air separator membranes are crucial in the nitrogen separation process.

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.

The correct answer states that no action needs to be taken because this is normal operation. The blower clutch will only engage at the governed speed, which means that it will not engage at 1,250 RPM. Therefore, there is no need to replace any parts or check any switches.

Frosting of a refrigeration system line or component indicates a blockage. When there is a blockage in the system, the flow of refrigerant is restricted, causing the temperature to drop and leading to the formation of frost. This can occur due to various reasons such as debris, ice buildup, or a malfunctioning component. Identifying and resolving the blockage is important to ensure proper functioning and efficiency of the refrigeration system.

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.

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.

During the operation of the EPU-6/E frequency converter, it has been determined that the E and F pin voltage is not required for the aircraft. Therefore, the loop/bypass/28 V to aircraft switch should be placed in the BYPASS position.

The probable cause for the excessively high exhaust gas temperature during the operation of a -60 is the pneumatic thermostat. The pneumatic thermostat is responsible for regulating the temperature of the engine by controlling the flow of air and fuel. If the pneumatic thermostat is malfunctioning or not functioning properly, it can result in an imbalance in the air-fuel mixture, leading to higher exhaust gas temperatures.

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.

The speed of the SGNSC's nitrogen booster compressor is determined by the programmable logic controller (PLC) circuit. The PLC circuit is responsible for controlling and regulating the operation of various components in the system, including the compressor. It receives input signals, processes them according to a programmed logic, and generates output signals to control the speed and operation of the compressor. By adjusting the parameters and logic within the PLC circuit, the speed of the compressor can be effectively controlled to meet the desired requirements of the system.

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.

When the main tanks are 3/4 full, fuel transfer to the main tanks stops. This means that once the main tanks reach 75% capacity, the fuel transfer from the auxiliary tank to the main tanks is halted. This is likely done to prevent overfilling of the main tanks and to ensure that there is enough fuel remaining in the auxiliary tank for future use.

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

The -16 load bank requires the use of both verification and resistance check boards for maintenance and troubleshooting. These boards are essential for ensuring that the load bank is functioning properly and that the resistance values are within acceptable limits. The verification board helps to verify the overall performance and functionality of the load bank, while the resistance check board is specifically used to check and measure the resistance values of the load elements. Using both boards together allows for a comprehensive assessment of the load bank's condition and helps in identifying any issues or faults that may need to be addressed.

The correct answer is "Never, the load bank automatically performs calibrations when input values are outside acceptable tolerances." This means that the load bank will automatically calibrate itself when the input values deviate from the acceptable range. Therefore, there is no need to manually perform a current or voltage calibration on the load bank.

The correct answer is "rate control" because it is the component in the -60 gas turbine engine load control valve assembly that controls the opening time of the butterfly valve. It regulates the rate at which the valve opens, allowing for precise control of the engine's load.

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".

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.

The oil pressure relief valve controls the output of the main oil pump by bypassing excess oil back to the main pump inlet. This means that when the oil pressure exceeds a certain level, the relief valve opens and diverts the excess oil back to the inlet of the main pump, preventing damage to the system. This helps regulate the oil pressure and ensures that it remains within the desired range for optimal engine lubrication.

When the butterfly valve is closed on a -95, chambers 1, 3, and 4 are pressurized.

The probable cause of the DC voltmeter on a -60 failing to indicate during operation is that TR1 is defective. TR1 is a component that could be responsible for the malfunction of the voltmeter, causing it to fail to indicate the correct readings.

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

The correct answer is every 6 months because the question is asking for the minimum interval at which the input and output terminals of the EPU-6/E are inspected. This means that the terminals need to be inspected at least once every 6 months to ensure proper functioning and maintenance of the EPU-6/E.

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.

When a -60 is started, the ignition unit de-energizes when the engine reaches 95 percent of its speed. This is because the ignition unit is responsible for providing the spark that ignites the fuel-air mixture in the engine cylinders. Once the engine reaches 95 percent of its speed, the ignition unit is no longer needed as the combustion process is self-sustaining. Therefore, it is de-energized to conserve energy and prevent any potential damage to the engine.

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.

The torus assembly is the correct answer because it is the engine component that accelerates hot expanding gases and directs them into the nozzle ring. The torus assembly is designed to efficiently channel and control the flow of gases, ensuring optimal performance and thrust generation in the engine.

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.

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.

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.

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.

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.

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.

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.

When the output air temperature of the MA-3D air conditioner is too high, setting the temperature control to maximum cooling is done to decrease the temperature. In this scenario, the temperature controller sends a signal to B7, which steps open to meter refrigerant into the evaporator. This means that B7 opens up to allow a controlled amount of refrigerant to enter the evaporator, which helps in the cooling process.

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.

When K25 is energized during the operation of a -60, it does not cause any negative effects or disruptions. The unit continues to operate normally without any issues.