2A551 Practice Test Volume 2

Phase is the term used to express a condition in which two moving objects are changing in or out of step. In the context of electricity or waveforms, phase refers to the relationship between two or more waveforms. When two waveforms are in phase, their peaks and troughs align, resulting in constructive interference. When they are out of phase, their peaks and troughs do not align, resulting in destructive interference. Therefore, phase is the correct answer to describe the condition of two moving objects changing in or out of step.

The correct answer is 150F to 280F. This is because the H-1 heater has an adjustable heat output that can be set anywhere between 150F and 280F. This range allows the user to choose the desired temperature for their heating needs.

Stringers are structural members that are used to give shape to the aircraft and provide a means for attaching the skin to the structure. They run longitudinally along the fuselage and wings, providing support and rigidity to the overall structure. Longerons are also structural members that run longitudinally, but their chief use is to carry the primary loads of the aircraft. Bulkheads are vertical partitions that provide structural support and divide the fuselage into compartments. Frames are horizontal or vertical structural members that provide support and shape to the aircraft structure. Therefore, the correct answer is stringers.

When making a right turn, the relative position of the ailerons is up, left aileron down. This means that the right aileron is raised or moved upwards, while the left aileron is lowered or moved downwards. This configuration helps to increase the lift on the right wing and decrease the lift on the left wing, causing the aircraft to roll to the right and initiate the turn.

A fowler flap is a type of flap that is commonly used on bomber and cargo aircraft. It is designed to increase the wing area and provide additional lift during takeoff and landing. The fowler flap extends both downwards and backwards, increasing the wing surface area and allowing for better control at low speeds. This type of flap is especially useful for larger aircraft that require high lift capabilities.

The Stratopower variable-volume pump uses a nutating plate to hold the pistons in contact with the cam plate. A nutating plate is a disc-shaped component that moves in a circular motion while maintaining contact with the pistons. This design ensures that the pistons are properly aligned and can move smoothly along the cam plate, allowing for efficient pumping action. The nutating plate acts as a stabilizing element, preventing any misalignment or displacement of the pistons during operation.

A pneudraulic system component that uses a double-acting balanced actuating cylinder is the nosewheel steering. This component allows for controlled steering of the aircraft's nosewheel. The double-acting cylinder ensures that the steering can be actuated in both directions, providing balanced and precise control over the nosewheel.

The term "craking pressure" refers to the pressure at which the relief valve ball is slightly unseated. This means that the valve opens slightly to release excess pressure from the system. The other options, normal system pressure, full flow pressure, and reseating pressure, do not accurately describe this specific pressure point at which the relief valve begins to open.

The correct answer is "supply, pressure, return, and auxiliary." In a basic hydraulic system, the supply section is responsible for providing the fluid required for operation. The pressure section controls the flow and pressure of the fluid. The return section allows the fluid to return to the reservoir after it has been used. The auxiliary section consists of additional components such as filters, valves, and accumulators that enhance the system's performance.

A relief valve is installed in a variable volume hydraulic pump to relieve pressure if the pump compensator fails. The pump compensator is responsible for regulating the pressure of the hydraulic system. If the compensator fails, it can lead to excessive pressure buildup within the system, which can be dangerous and potentially cause damage. The relief valve acts as a safety mechanism by opening up and allowing excess pressure to be released, thus preventing any potential damage or hazards.

A 24 volt nickel cadmium battery typically has 19 cells. Each cell in a nickel cadmium battery produces around 1.2 volts, so to achieve a total voltage of 24 volts, 19 cells would be required.

According to the principle of fluid dynamics, as fluid enters the narrow portion of a venturi, it accelerates. This is because the narrow portion creates a constriction in the flow, causing the fluid to speed up in order to maintain the same flow rate. This acceleration leads to a decrease in pressure according to Bernoulli's principle. Therefore, the correct answer is "it accelerates."

The hollow end of the accumulator's piston should be installed toward the air side of the accumulator. This allows the piston to move freely and create a seal with the air side, preventing any air from entering the fluid side. If the hollow end was installed toward the fluid side, it would not create an effective seal and could cause air to mix with the fluid, reducing the accumulator's efficiency. Installing the piston with the drilled passage toward the air side would also not create a proper seal and could result in air leakage.

A filter rated at microns nominal means that it is designed to filter out particles of a certain size, but it may not be able to capture all particles exactly at that size. Therefore, it may allow some particles that are 10 microns or larger to pass through, while still effectively filtering out smaller particles.

The correct answer is 365 hz. The underspeed switch (USS) on the 60/80 kilovolt ampere (KVA) generator constant speed drive (CSD) actuates at 365 hz. This means that if the frequency of the generator drops below 365 hz, the underspeed switch will be activated. This is an important safety feature as it helps to prevent damage to the generator by shutting it down if it is running at a dangerously low speed.

The hydraulic systems on the MK-3A-1 hydraulic test stand are designated as No 1 and No 2. This means that there are two separate hydraulic systems on the test stand, each labeled as No 1 and No 2. This labeling system helps to differentiate and identify the different hydraulic systems and their components on the test stand.

The correct answer is lateral. The axis that extends crosswise from wingtip to wingtip is called the lateral axis. This axis is responsible for the rolling motion of an aircraft, allowing it to tilt from side to side. The lateral axis is perpendicular to the longitudinal axis, which runs from the nose to the tail of the aircraft, and the vertical axis, which runs from top to bottom.

The term "power control cylinders" is used by some aircraft manufacturers to refer to tandem actuators. Tandem actuators are hydraulic or pneumatic devices that provide control and actuation of various aircraft systems. They are designed to work in tandem, meaning they operate together to provide a higher level of force or control. These actuators are commonly used in aircraft control surfaces, landing gear systems, and other critical flight control systems.

In most hydraulic subsystems, the actuating units are connected in parallel. This means that the actuating units are connected side by side, allowing them to operate independently of each other. This configuration enables each actuating unit to perform its function simultaneously, resulting in increased efficiency and faster operation of the hydraulic system. Additionally, connecting the units in parallel provides redundancy, as if one unit fails, the others can still continue to operate.

Deboosters are used to reduce braking pressure. They are hydraulic devices that work by decreasing the force applied to the brake pedal, resulting in a decrease in the pressure exerted on the braking system. This is particularly useful in situations where the braking force needs to be controlled or reduced, such as when driving on slippery surfaces or when a lighter touch is required for braking. By reducing the braking pressure, deboosters help to prevent wheel lock-up and provide a smoother and more controlled braking experience.

The internal component of a battery that is a grid or framework, which supports the active chemical materials, is the plate. The plate acts as a conductor and provides a surface for the chemical reactions to occur, allowing the battery to generate and store electrical energy. The plate is typically made of a material such as lead or lithium, depending on the type of battery.

The MD-4 is the correct answer because it is a stationary, skid-mounted power unit specifically designed to produce aircraft electrical power for use in shops and hangars. The other options (A/M32A-95, MK-3A, and MB-2) do not fit the description of a stationary, skid-mounted power unit for aircraft electrical power.

The left hand rule for conductors is used to determine the direction a current carrying conductor will move in a magnetic field. According to this rule, if the thumb of the left hand points in the direction of the current flow and the fingers point in the direction of the magnetic field, then the palm will indicate the direction in which the conductor will move. This rule is based on the principle of Fleming's left-hand rule and is commonly used in physics and electrical engineering to understand the interaction between magnetic fields and electric currents.

When the nickel-cadmium battery cells are partially discharged, the electrolyte will appear to be low. This is because as the battery discharges, the electrolyte reacts with the active materials in the cells, causing a decrease in the electrolyte level. This can give the false impression that the battery is running out of electrolyte, when in reality it is just partially discharged. It is important to note that this is a characteristic of nickel-cadmium batteries and not necessarily applicable to other types of batteries.

The correct answer is reservoir, pump, actuator, and manual shutoff valve. In a hydraulic hand pump system, the reservoir stores the hydraulic fluid, the pump is responsible for creating pressure by pumping the fluid, the actuator converts the pressure into mechanical force, and the manual shutoff valve controls the flow of fluid. The shut off and metering valve mentioned in one of the options are not typically considered as basic units in a hydraulic hand pump system.

The landing gear control lever is connected to the selector valve using a cable system. This means that when the lever is moved, it pulls or pushes on the cable, which in turn moves the selector valve. This allows for precise control and reliable transmission of the motion from the lever to the valve.

The explanation for the given answer is that the reservoir supplies hydraulic fluid to the hand pump by gravity and the suction effect of the pump. Gravity helps in creating a flow of fluid from the reservoir to the pump, while the suction effect of the pump aids in drawing the fluid from the reservoir. Together, these two factors ensure a continuous supply of hydraulic fluid to the hand pump.

Torsion links are responsible for actuating the landing gear safety switches. These links are designed to absorb and distribute the forces and vibrations encountered during landing and takeoff. When the landing gear is engaged or retracted, the torsion links move and trigger the safety switches, ensuring that the gear is securely locked in place. Therefore, torsion links play a crucial role in the safe operation of landing gear systems.

Hook's Law states that the distortion of any elastic body is proportional to the distorting force. This means that when a force is applied to an elastic body, such as stretching or compressing a spring, the amount of deformation or change in length is directly proportional to the force applied. In other words, the more force applied, the more the elastic body will deform. This law is commonly used in physics and engineering to understand and predict the behavior of elastic materials.

The correct answer is hydraulic and pneumatic. Hydraulic brake systems use fluid pressure to transmit force from the brake pedal to the brakes, while pneumatic brake systems use compressed air. Both systems are commonly used in emergency brake systems due to their ability to generate and transmit large amounts of force quickly, making them reliable and effective in emergency situations.

A pneudraulic system is a combination of pneumatic and hydraulic systems. In this context, a single-acting actuating cylinder refers to a cylinder that can only generate force in one direction. Among the given options, the brake assembly is the most suitable component that uses a single-acting actuating cylinder. When the brake pedal is pressed, the pneudraulic system applies hydraulic pressure to the brake assembly, causing the brake pads to clamp onto the brake disc or drum, thus slowing down or stopping the vehicle.

The term "ply rating" refers to the index of tire casing strength. Ply rating is a measure of the strength and durability of a tire's casing. It indicates the number of layers of reinforcing fabric, or plies, that are used in the construction of the tire. A higher ply rating typically indicates a stronger and more robust tire that is capable of handling heavier loads and higher speeds.

The correct answer is 0-350, 350-3600. This means that the NSU-L75 nitrogen servicing unit has a low pressure capability of 0-350 PSI and a high pressure capability of 350-3600 PSI.

The category III equipment is used for life support and crew comfort. This category includes equipment that is essential for maintaining the health and well-being of the crew members, such as oxygen systems, environmental control systems, and waste management systems. These equipment are crucial for providing a safe and comfortable environment for the crew during their mission.

When measuring resistance on a multimeter, the letter OL indicates infinity. This means that the resistance being measured is too high for the range of the multimeter. It could be due to an open circuit or a component with extremely high resistance. The multimeter is unable to measure such high resistance values, so it displays OL to indicate an infinite resistance.

The correct answer is piston and vane. Shimmy dampers are used in nose wheel steering to prevent shimmy, which is an oscillation of the wheel. The piston and vane type of shimmy damper consists of a piston that moves within a cylinder filled with hydraulic fluid. As the wheel oscillates, the piston moves back and forth, causing the fluid to flow through the vane, which helps dampen the oscillations and stabilize the wheel. This type of shimmy damper is commonly used in aircraft nose wheel steering systems.

The bearing cone of an aircraft wheel bearing is called the inner race. The inner race is the part of the bearing that rotates with the shaft and holds the rolling elements (such as rollers or balls) in place. It is typically located inside the outer race, which is the stationary part of the bearing. The inner race is responsible for transmitting the load from the rotating shaft to the rolling elements, allowing for smooth and efficient rotation of the wheel.

Brinelling refers to the indentation of a surface caused by the application of a heavy load. It can occur in two different ways: true brinelling and false brinelling. True brinelling happens when the load is stationary and causes permanent deformation of the surface, resulting in visible indentations. On the other hand, false brinelling occurs when there is relative motion between the load and the surface, causing fretting and wear but without leaving permanent indentations. Therefore, the correct answer is "true and false" as it accurately describes the two types of brinelling.

Pascal's Law states that when a fluid is confined and at rest, the pressure is transmitted equally in all directions. This means that if pressure is applied to a confined fluid, it will be transmitted undiminished to all parts of the fluid and the walls of the container. Therefore, the correct answer is "confined fluids at rest" because Pascal's Law specifically applies to this scenario.

A servo valve is a type of valve that is specifically designed to control the flow of fluid. It is electrically operated, meaning that it can be controlled remotely using an electrical signal. On the other hand, a selector valve is a type of valve that has four parts and is more complex in design. While it may also control fluid flow, the main difference between the two is that a servo valve is specifically designed for this purpose, whereas a selector valve may have other functions as well.

The high pressure pump is responsible for pressurizing the hydraulic filler unit. The question asks for the maximum pressure provided by the pump. Among the given options, the highest pressure mentioned is 3000 PSI. Therefore, the correct answer is 3000 PSI.

The correct answer is engine oil and blast air. Brushless AC generators require cooling to prevent overheating. Engine oil is used to cool the generator's internal components, such as the rotor and stator, which generate heat during operation. The oil absorbs the heat and carries it away, helping to maintain a safe operating temperature. Blast air is also used to cool the generator by blowing air over the external surfaces, dissipating heat and preventing the buildup of hot air around the generator. This combination of engine oil and blast air cooling ensures efficient and effective cooling for brushless AC generators.

Corrosive and mechanical pittings are the types of pittings that affect bearings. Corrosive pittings occur when the bearing is exposed to corrosive substances, such as acids or chemicals, which gradually erode the surface of the bearing. On the other hand, mechanical pittings happen due to excessive loads, vibrations, or friction, causing localized damage on the bearing surface. Both corrosive and mechanical pittings can lead to reduced bearing performance, increased wear, and potential failure if not addressed promptly.

The correct answer is elevator. The elevator is the flight control located on the longitudinal control surface of an aircraft. It is responsible for controlling the pitch or the up and down movement of the aircraft. By changing the elevator's position, the pilot can adjust the aircraft's attitude and control its climb or descent. The rudder controls the yaw or the left and right movement, the ailerons control the roll or the tilting movement, and the wing flaps control the lift and drag during takeoff and landing.

Boyle was among the first to study the compressibility of gases. He is known for Boyle's Law, which states that the volume of a gas is inversely proportional to its pressure, assuming the temperature remains constant. Through his experiments, Boyle made significant contributions to the understanding of gas behavior and laid the foundation for the development of the field of gas laws.

The MC-2A air compressor is capable of delivering air at a maximum pressure of 200 PSI.

Bernoulli's principle states that as the velocity of a gas or liquid increases, the pressure decreases. This principle is based on the conservation of energy, stating that as the speed of a fluid increases, its potential energy decreases, resulting in a decrease in pressure. This principle is commonly observed in various phenomena, such as the lift force on an airplane wing and the flow of fluids through pipes. Therefore, Bernoulli's principle is the correct explanation for the given statement.

The usable pressure range of the MC-1A air compressor is 0-3200 PSI. This means that the compressor is capable of producing a minimum pressure of 0 PSI and a maximum pressure of 3200 PSI. This range allows the compressor to be used for a variety of applications that require different levels of pressure, providing versatility and flexibility in its use.

Charles is the correct answer because he discovered Charles's Law, which states that gases expand and contract in direct proportion to the change in temperature, provided the pressure remains constant. This law is also known as the law of volumes and is an important principle in the study of thermodynamics.

Atmospheric pressure at sea level is 29.92 PSI. This is the standard atmospheric pressure at sea level, also known as one atmosphere of pressure. It is the average pressure exerted by the Earth's atmosphere on a surface at sea level. This value is commonly used as a reference point for measuring pressure in various applications, such as weather forecasting, aviation, and scuba diving.