2AX5X Volume 3

A centrifugal pump with an electrically driven, direct current (DC), series-wound motor must have a fuel- and vapor-proof housing because it is used to pump fuel. This type of pump is commonly used in automotive applications and needs to be able to handle fuel and prevent any leakage or vapor escape, which could be dangerous. A fuel- and vapor-proof housing ensures that the pump operates safely and efficiently without any risk of fuel leakage or vapor emissions.

Expansion joints in bleed air systems are best used for a short run of ducting. This is because expansion joints are designed to absorb thermal expansion and contraction in the ducting system. In a short run of ducting, there is less distance for the expansion and contraction to occur, so an expansion joint can effectively accommodate the movement without causing stress or damage to the system. In a long run of ducting, the expansion and contraction may be more significant, requiring additional expansion joints or alternative solutions. Therefore, a short run of ducting is the most appropriate application for expansion joints in bleed air systems.

The correct answer is butterfly. A disc type valve in a fuel system is commonly referred to as a butterfly valve. This type of valve consists of a disc or plate that rotates to control the flow of fuel. The disc is positioned in the middle of the pipe and resembles the shape of a butterfly, hence the name. It is designed to open and close smoothly, allowing precise regulation of the fuel flow. The other options mentioned, such as swivel vane, sliding gate, and swinging disc, do not accurately describe the specific type of valve commonly used in fuel systems.

In a fixed-isobaric, single-differential pressurization system, the action of the outflow valve is controlled by regulating control chamber pressure. This means that the pressure in the control chamber is adjusted to control the opening and closing of the outflow valve, which in turn regulates the cabin pressure. By adjusting the control chamber pressure, the system can maintain a constant cabin pressure regardless of changes in altitude or external conditions.

Jet engine tachometer gauges are calibrated in percent of maximum RPM because the tachometer measures the rotational speed of the engine. By calibrating it in percent of maximum RPM, it allows pilots and mechanics to easily monitor and control the engine's speed within safe operating limits. This calibration provides a reference point for determining if the engine is operating at its optimal speed or if any adjustments need to be made to maintain its performance.

Directing air around the plug electrode helps prevent igniter plug fouling by ensuring that there is sufficient airflow to keep the electrode clean. This airflow helps to remove any deposits or contaminants that may accumulate on the electrode, which can hinder the spark and cause fouling. By directing air around the plug electrode, the design promotes better combustion and prevents fouling, leading to improved engine performance.

Lock strips are used to secure the turbine bucket in place on some jet engines. These strips provide a strong and reliable method of holding the turbine bucket securely, preventing any movement or dislodgement during operation. Screws, cables, and lockwire are not typically used for this purpose.

The purpose of the engine bleed air (EBA) check valves is to prevent the loss of compressed bleed air. These valves ensure that the air being bled from the engine for various purposes, such as cabin pressurization and air conditioning, remains within the system and does not escape. By preventing the loss of compressed bleed air, the check valves help maintain the efficiency and effectiveness of the aircraft's systems that rely on this air supply.

A centrifugal-type aircraft fuel pump may be used for boost, transfer, or air refueling operations because it is capable of delivering fuel at high pressure and flow rates, which are necessary for these operations. The centrifugal design of the pump allows it to generate the required pressure by using centrifugal force to push the fuel outward. Additionally, the absence of moving parts in the pump reduces the risk of mechanical failure, making it suitable for use in various operational scenarios.

A dual-impeller centrifugal pump is used when a fuel supply is required during periods of negative gravity conditions. This type of pump is designed with two impellers that work together to provide a continuous flow of fuel even in situations where gravity is working against the flow. The dual-impeller design allows for efficient pumping and ensures a reliable fuel supply in challenging conditions.

Movable inlet and exit doors control the flow of ram air through the primary heat exchangers in an aircraft air conditioning system. These doors can be adjusted to regulate the amount of air entering and exiting the heat exchangers, allowing for proper cooling or heating of the air before it is distributed throughout the aircraft. By controlling the flow of ram air, the movable inlet and exit doors help maintain the desired temperature and comfort level inside the aircraft cabin.

The question asks about the size of specks or granules of sediment in fuel that can be seen with the naked eye. The correct answer is 40 microns because it is the closest option to being visible to the naked eye. Microns are a unit of measurement for small particles, and 40 microns is large enough to be seen without the aid of a microscope.

Inertia is the property of matter that describes its resistance to change in motion. It is the tendency of an object to stay at rest or continue moving with a constant velocity unless acted upon by an external force. Energy is not the correct answer as it is the ability to do work or cause a change. Friction is the force that opposes motion, but it is not the property of matter being referred to in the question. Potential is a measure of stored energy, but it is not directly related to the resistance of an object to change its motion.

The correct answer is degrees Celsius because exhaust gas temperature indicators are used to measure the temperature of the engine's exhaust gases. Celsius is the standard unit of temperature measurement in most countries, including the metric system used in the automotive industry. Therefore, EGT indicators would typically display the temperature in degrees Celsius.

An inlet screen prevents foreign objects from holding the bypass valve open in a dual-impeller fuel pump. This screen acts as a filter, allowing only fuel to pass through while blocking any debris or foreign objects that could potentially interfere with the bypass valve. By keeping the bypass valve free from obstruction, the inlet screen ensures proper functioning of the fuel pump and prevents any potential damage or malfunction caused by foreign objects.

Vent holes prevent fiberglass fabric ducts from swelling when the aircraft climbs to high altitudes. As the aircraft ascends, the air pressure decreases, causing a potential for the air trapped within the ducts to expand. However, the presence of vent holes allows the air to escape, preventing the ducts from swelling or becoming damaged. This ensures the proper functioning and integrity of the duct system during high altitude flights.

The correct answer is without draining the fuel lines or tanks. This means that the rotary plug valve can be removed and replaced without the need to empty or drain the fuel lines or tanks. This suggests that the valve is designed in a way that allows for easy removal and replacement without causing any fuel spillage or leakage.

The two types of jet engine compressors are centrifugal and axial-flow. Centrifugal compressors work by using centrifugal force to increase the pressure of the air, while axial-flow compressors use a series of rotating and stationary blades to compress the air. These two types of compressors are commonly used in different types of jet engines, with centrifugal compressors typically found in smaller engines and axial-flow compressors used in larger engines for higher efficiency.

The molecular sieve oxygen generating system (MSOGS) concentrator supplies the OXYGEN regulator control panel with 93 percent oxygen-enriched gas. This means that the gas being supplied has a higher concentration of oxygen compared to the surrounding air, which is typically around 21 percent oxygen. The MSOGS concentrator uses a molecular sieve to selectively remove nitrogen and other gases from the air, resulting in a higher concentration of oxygen in the output gas. This oxygen-enriched gas can then be used for various applications, such as medical purposes or in aircraft systems.

The handle on a manually operated buildup and vent valve is designed to prevent the filler access door from closing in the vent position. This means that when the valve is in the vent position, the handle ensures that the filler access door remains open, allowing for the rapid venting of system pressure. This is important to prevent any potential pressure buildup and ensure the safe operation of the liquid oxygen (LOX) system.

A compressible flange is a type of high-pressure/high-temperature ducting that does not require a gasket. This type of flange uses a compressible material, such as rubber or elastomer, to create a seal between the two mating surfaces. When the flange is tightened, the compressible material is compressed, creating a tight and secure seal without the need for a gasket. This design is often used in applications where a gasket may not be suitable or where a more flexible seal is required.

A compensator is a component in a capacitance-type, fuel-indicating system that allows for changes in fuel density. It is designed to adjust the capacitance measurement to account for variations in the density of the fuel being measured. This is important because the density of fuel can vary due to factors such as temperature and composition. By using a compensator, the fuel-indicating system can provide accurate and reliable measurements of fuel levels regardless of changes in fuel density.

The purpose of the pneumatic relay in a cabin pressurization system is to ensure that both outflow valves operate at the same time. This is important for maintaining the desired cabin pressure. If the outflow valves do not operate simultaneously, it can lead to an imbalance in cabin pressure, causing discomfort or potential safety issues for passengers and crew. The pneumatic relay helps to synchronize the operation of the outflow valves, ensuring that they open and close together to maintain the desired pressure in the cabin.

The temperature and pressure of the aircraft engine in relation to the bleed air system are influenced by the engine throttle setting and the ambient temperature. The engine throttle setting determines the amount of fuel and air mixture being supplied to the engine, which affects the temperature and pressure. Meanwhile, the ambient temperature refers to the temperature of the surrounding environment, which can also impact the engine temperature and pressure. Therefore, both factors play a role in determining the temperature and pressure of the aircraft engine in the bleed air system.

Bearings in an air refueling pump depend on fuel for lubrication. Bearings are components that support the rotating parts of the pump, allowing them to move smoothly. In this case, the bearings rely on the fuel to provide lubrication, reducing friction and preventing damage to the pump's moving parts. The other components mentioned, such as rotors, stators, and impellers, may also be present in an air refueling pump, but they do not specifically require fuel for lubrication.

The air-refueling receptacle is operated by hydraulic power, meaning that it uses hydraulic pressure to control its movements. However, the control of the receptacle is done electrically, meaning that electrical signals are used to activate and control the hydraulic system.

The correct answer is that a jet engine uses an exhaust-gas-driven turbine wheel to drive its compressor. This is because a jet engine operates by taking in air, compressing it with a turbine-driven compressor, and then mixing it with fuel and igniting it to create high-speed exhaust gases. These exhaust gases then pass through a turbine wheel, which is connected to the compressor, causing it to spin and continue the cycle. This exhaust-gas-driven turbine wheel is what drives the compressor and allows the jet engine to maintain power.

In a fire warning system, the normal connection for thermal switches is in parallel with each other and with the warning light. This means that all the thermal switches are connected to each other in a parallel circuit, and this parallel circuit is also connected in parallel with the warning light. This configuration ensures that if any of the thermal switches detect a rise in temperature, the circuit will be completed and the warning light will be activated, indicating a fire hazard.

The frangible disc is the component of a liquid-agent fire extinguisher container that holds both the liquid agent and the nitrogen charge. A frangible disc is a thin, breakable disk that is designed to rupture when the extinguisher is activated, allowing the agent and charge to be released. It acts as a barrier between the liquid agent and the nitrogen charge, ensuring that they are kept separate until needed.

Float switches are the most likely control mechanism for automatically shutting off a pump when all fuel is depleted from a fuel tank. Float switches are commonly used in fuel tanks to detect the level of liquid. When the fuel level drops below a certain point, the float switch will activate and send a signal to shut off the pump, preventing it from running dry and potentially causing damage.

The torque supplied by the jet fuel starter (JFS) is transmitted to the engine gearbox through the power takeoff (PTO) shaft. The PTO shaft acts as a mechanical connection between the JFS and the engine gearbox, allowing the torque to be transferred effectively. It is designed to handle the power and rotational forces generated by the JFS, ensuring a smooth and efficient transmission of torque to the engine gearbox.

The inner and outer surfaces of an annular-type combustion chamber are formed by interlocking stainless steel bands. These bands provide structural integrity and prevent the escape of hot gases during the combustion process. The interlocking design ensures a tight seal and helps maintain the efficiency and safety of the combustion chamber.

During the early years of jet engine design, the most basic turbine engine design used was the turbojet. Turbojets operate by sucking in air, compressing it, and then burning fuel in the compressed air to produce thrust. The exhaust gases from the burning fuel are then expelled at high velocity, creating forward propulsion. This design was widely used in the early development of jet engines and served as the foundation for further advancements in turbine engine technology.

The primary function of a hydromechanical fuel control on a jet engine is to meter the fuel, making certain that the engine gets the correct quantity for combustion at all times. This means that the fuel control regulates the flow of fuel to the engine, ensuring that the engine receives the appropriate amount of fuel for efficient combustion. This is important for maintaining the engine's performance, preventing issues such as hot starts, overtemperatures, engine overspeeding, and flameouts. By accurately metering the fuel, the fuel control helps to optimize the engine's operation and prevent any potential damage or malfunctions.

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The secondary heat exchanger removes most of the increased temperature in the air cycle machine. As bleed air enters the compressor, its pressure is increased, leading to an increase in temperature. The secondary heat exchanger is responsible for transferring this excess heat to the surrounding environment, allowing the air cycle machine to maintain its efficiency and prevent overheating.

An aircraft taxiing at a constant speed is an example of Newton's First Law of Motion, also known as the law of inertia. According to this law, an object in motion will continue to move at a constant velocity unless acted upon by an external force. In this case, the aircraft is moving at a constant speed, indicating that no external force is acting on it to change its velocity. This aligns with Newton's First Law, making it the correct answer.

When the turbine wheel absorbs the fuel energy, a certain percentage of it is used for accessories. However, the remaining energy is returned to the compressor. This is important because the compressor needs a continuous flow of energy to function properly and maintain the necessary air pressure for the engine. By returning the energy to the compressor, it ensures that the engine operates efficiently and effectively.

The correct answer is "The movement of a float in the tanks." In a direct current (DC), liquid-level fuel indicating system, the wiper contact on the resistance strip is positioned by the movement of a float in the tanks. As the float moves up or down with the changing fuel level, it adjusts the position of the wiper contact on the resistance strip, which in turn affects the electrical signal sent to the indicator circuit. This allows for accurate measurement and indication of the fuel level in the tanks.

The fuel control in a jet engine is responsible for metering the fuel for combustion. It regulates the flow of fuel to ensure the correct fuel-to-air ratio is maintained for efficient combustion. By controlling the fuel flow, the fuel control helps in maintaining the engine's performance, fuel efficiency, and overall operation.

The shutoff valve is the component that prevents loss of air through the engine when it is shutdown. This valve is designed to close off the flow of bleed air, ensuring that it does not escape from the engine. By closing the shutoff valve, the bleed air is effectively contained within the engine, preventing any loss or leakage. This helps to maintain the integrity of the air system and ensures that the bleed air is available for use when the engine is started up again.

The third law of motion, also known as Newton's law of action and reaction, states that for every action, there is an equal and opposite reaction. In the case of an operating jet engine, the forward thrust is generated by the engine expelling a high-speed stream of gases in one direction (action), which in turn pushes the engine and the aircraft forward (reaction). This is a perfect example of Newton's third law, where the action of expelling gases backward results in the reaction of the aircraft moving forward.

A turbofan engine with a bypass ratio of 3:1 is classified as a medium bypass. The bypass ratio refers to the amount of air that bypasses the core of the engine compared to the amount of air that goes through the core. In this case, with a bypass ratio of 3:1, it means that for every 3 units of air that bypasses the core, 1 unit of air goes through the core. This ratio falls within the range of a medium bypass engine.

A check valve is a type of valve that allows the flow of fluid (in this case, gaseous oxygen) in only one direction. It prevents backflow, ensuring that oxygen does not flow back into the system and cause a complete loss. Therefore, a check valve is the correct valve type to prevent a complete loss of oxygen in a gaseous oxygen (GOX) system.

The N2 compressor rotations per minute (RPM) of a dual-spool jet engine compressor is determined by the fuel control. The fuel control regulates the amount of fuel being supplied to the engine, which in turn affects the speed at which the compressor rotates. By adjusting the fuel flow, the fuel control can increase or decrease the RPM of the compressor, allowing for precise control over the engine's performance.

A gerotor is a type of jet engine oil pump that consists of a gear and rotor within a housing. This design allows for efficient and reliable oil pumping in jet engines. The gear and rotor work together to create a positive displacement pumping action, which ensures a steady and consistent flow of oil throughout the engine. The gerotor design is commonly used in jet engines due to its compact size, high efficiency, and ability to handle high pressure and temperature conditions.

A flameholder is a component that creates local turbulence and reduces gas velocity in a combustion system. It is designed to stabilize the flame by creating recirculation zones that enhance fuel-air mixing and promote combustion efficiency. By slowing down the gas velocity, the flameholder prevents flame blowout and ensures a stable and continuous combustion process. The other options, such as spraybar, screech liner, and fuel manifold, do not have the specific function of creating turbulence and reducing gas velocity.

The correct answer is impulse, reaction, and reaction-impulse. These three turbine designs are commonly used in jet engines. The impulse turbine operates on the principle of the change in momentum of the fluid, while the reaction turbine operates on the principle of the change in momentum and pressure of the fluid. The reaction-impulse turbine combines both principles to achieve efficient power generation.

The correct answer is transformer. A transformer is a device that can increase or decrease the voltage of an alternating current (AC) signal. In the context of a jet engine ignition system, a transformer is used to step up the voltage from a lower level to 20,000 volts, which is then delivered to the igniter plugs. This high voltage is necessary to create a spark and ignite the fuel-air mixture in the engine. In contrast, an inverter is used to convert DC to AC, a capacitor stores electrical energy, and a generator produces electricity.

The correct answer is "air pressure, and pump". This means that the two methods of transferring fuel are using air pressure and using a pump. Air pressure can be used to push the fuel through a system, while a pump can be used to actively move the fuel from one place to another.

The purpose of a front-mounted fan in an axial-flow jet engine compressor is to increase thrust and send air through the compressor core rotor. The fan helps to draw in a large amount of air, which is then accelerated and directed towards the compressor core rotor. This increases the mass flow rate through the engine, resulting in higher thrust. Additionally, the fan also helps to compress the incoming air, increasing the pressure and temperature before it enters the combustion chamber, which further improves the engine's performance.

The spring aids piston closure and prevents fuel from entering the tank in a piston-type, fuel level control valve. The spring exerts force on the piston, helping to keep it closed and preventing any fuel from flowing back into the tank. This ensures that the fuel level remains controlled and regulated within the valve system.

The purpose of the jet engine pressure ratio (EPR) indicating system is to provide a reference for the engine's available thrust output. The EPR is a measure of the pressure ratio across the engine's compressor, which directly affects the amount of thrust the engine can produce. By monitoring the EPR, pilots and engineers can determine the engine's performance and make adjustments as necessary to optimize thrust output. Therefore, the EPR indicating system serves the purpose of indicating the engine's available thrust output.

A segmented flap is a common type of variable-area orifice used on augmenters. This type of flap is divided into segments, allowing for precise control of the flow area. By adjusting the position of the segments, the area of the orifice can be increased or decreased, thereby regulating the flow of fluid or gas. This design is often used in augmenters to optimize performance and achieve desired output.

If the dual-differential cabin pressure regulator fails during flight, the outflow valves would maintain the pressure. These valves are responsible for regulating the airflow in and out of the cabin, ensuring that the pressure remains at a safe and comfortable level. By adjusting the position of the outflow valves, the cabin pressure can be controlled even if the regulator fails.

The correct answer is cabin pressure controller fails. In an isobaric pressurization system, the cabin pressure controller is responsible for maintaining a constant pressure inside the aircraft cabin. If the cabin pressure controller fails, it means that it is no longer able to regulate the cabin pressure. In such a scenario, the manual control valve can be used as an alternate to manually control the cabin pressure and ensure the safety of the passengers and crew onboard.

The components of the differential section of the cabin pressure regulator are a diaphragm, spring, and metering valve. The diaphragm is responsible for sensing the pressure difference and initiating the necessary adjustments. The spring provides the necessary force for the diaphragm to function properly. The metering valve controls the flow of air to maintain the desired cabin pressure. This combination of components allows for the regulation and control of the cabin pressure in an aircraft.

The divergent design of a jet engine diffuser increases pressure. This is because the divergent shape of the diffuser allows the airflow to expand, which causes the velocity of the air to decrease and the pressure to increase. As the air flows through the divergent diffuser, it is gradually slowed down and compressed, resulting in an increase in pressure.

A simple direct current (DC) ignition system consists of a vibrator, which is responsible for creating the high voltage pulses needed for ignition. The igniter plugs are used to ignite the fuel-air mixture in the engine cylinders. The transformer is used to step up the voltage from the vibrator to a level sufficient for ignition. The AC-to-DC converter is not necessary in this system as it is designed to convert alternating current to direct current, which is not required for the DC ignition system. Therefore, the correct answer is vibrator, igniter plugs, and transformer.

The compressor must be rotated to a predetermined speed in order for a jet engine starter to be considered effective. The compressor is responsible for compressing incoming air, which is then mixed with fuel and ignited in the combustion chamber to produce thrust. By rotating the compressor, it ensures that there is sufficient air intake and compression for the engine to start and operate efficiently.

The correct answer is that the air turbine (impingement) starter used on jet engines has the advantages of less weight and fewer moving parts than other starters. This means that the air turbine starter is more efficient and reliable compared to other types of starters. It is designed to be lightweight and have fewer components, which reduces the chances of failure and increases the overall performance of the starter. This makes it a preferred choice for jet engines where weight and reliability are crucial factors.

The question asks for a type of oil pump that is not classified according to structure. The options provided are Gear, Gerotor, Rotogear, and Sliding vane. Gear and Gerotor are both types of oil pumps classified according to structure. Sliding vane is also a type of oil pump classified according to structure. Therefore, the correct answer is Rotogear, as it is not a recognized type of oil pump when classified according to structure.

A pressure-loaded fuel system check valve is used when gravity flow through the valve is undesirable. This means that the valve is designed to prevent fuel from flowing back due to gravity when it is not desired. This could be the case when the fuel needs to be directed to a specific location or when the fuel flow needs to be regulated in a certain way. The valve ensures that the fuel only flows in the desired direction and prevents any backflow caused by gravity.

The secondary seal sleeve is the part of the rotary plug valve that rotates and seals off the passage of fuel during plug valve removal. This means that when the plug valve is being removed, the secondary seal sleeve ensures that the fuel flow is completely sealed off, preventing any leakage or spillage. The other options, such as the initial seal, diaphragm seal, and primary seal sleeve, do not specifically rotate and seal off the passage of fuel during plug valve removal.

A check valve is designed to allow the flow of fluid in one direction only, preventing backflow. In this case, the low-level shutoff valve is preventing the reverse flow of fuel through the valve. A check valve achieves this by using a mechanism that closes automatically when the flow direction changes, such as a swinging disc or a ball. This ensures that the fuel can only flow in the desired direction and prevents any potential damage or safety hazards that could occur from reverse flow.

The correct answer is "leak category and fuel type." This means that the limits for leaks are determined by both the category of the leak (i.e., the severity or type of leak) and the type of fuel being leaked. This suggests that different types of fuel may have different allowable leak limits, and that the severity of the leak may also impact the permissible limits.

The cartridge-pneumatic starter is a gas-driven turbine wheel that is connected to the engine through a reduction gear system and a power takeoff (PTO) shaft. The purpose of the overrunning clutch is to allow the turbine wheel to spin freely when the engine is running at a higher speed than the starter, preventing damage to the starter. This allows for smooth engagement and disengagement of the starter from the engine, ensuring proper functioning of the starter system.

When automatic data systems are not available, the form that must be used to document fuel leaks in addition to the Air Force Technical Order (AFTO) Form 781A or AFTO Form 781K is AFTO Form 427. This form is specifically designed for documenting fuel leaks and is used when automatic data systems are not accessible. It allows for the proper recording and tracking of fuel leaks, ensuring that they are documented and addressed appropriately.

When a jet engine uses two or more turbine wheels, a nozzle diaphragm is placed directly in front of each turbine wheel. The nozzle diaphragm helps to control the flow of exhaust gases from the combustion chamber into the turbine, ensuring efficient power transfer and optimal performance of the turbine wheels.

The rotor is the component in an air refueling pump that removes fuel vapors caused by the centrifugal force of the impellers. The impellers create the centrifugal force, which pushes the fuel towards the outer edges of the pump. The rotor then captures and removes any fuel vapors that are generated during this process. This helps to ensure that the fuel being transferred is free from any vapors, which could potentially cause issues during the refueling process.

Spring-loaded relief valves are fuel system components that prevent excessive pressure from building up in trapped lines or within the valve body. These valves are designed with a spring mechanism that opens when the pressure exceeds a certain threshold, allowing the excess pressure to be released and preventing damage to the system. Unlike thermal-relief valves, pressure-relief valves, and one-way check valves, spring-loaded relief valves are specifically designed to handle and regulate pressure in fuel systems.

The exhaust duct connects the turbine outlet to the jet nozzle. The jet nozzle is responsible for accelerating and directing the exhaust gases out of the engine, generating thrust. Therefore, it makes sense for the exhaust duct to connect to the jet nozzle in order to efficiently transfer the exhaust gases and produce propulsion.

The correct answer is sliding gate, rotary plug, and disc. This means that the three types of shutoff valves used in the crossfeed fuel system are the sliding gate valve, the rotary plug valve, and the disc valve. These valves are used to control the flow of fuel and to shut off the fuel supply when necessary.