1.
It is important to raise the air temperature in a jet engine to
Correct Answer
A. Increase its energy
Explanation
Raising the air temperature in a jet engine increases its energy because it allows for better combustion of fuel. When the air temperature is increased, the fuel burns more efficiently, resulting in a higher energy output. This increase in energy improves the overall performance of the jet engine, allowing it to generate more thrust and power. Therefore, increasing the air temperature is crucial for maximizing the energy output of the engine.
2.
In a jet engine, the velocity of the air is decreased by the
Correct Answer
A. Diffuser
Explanation
The correct answer is diffuser. A diffuser is a component in a jet engine that is responsible for decreasing the velocity of the air. It does this by expanding the air and slowing it down before it enters the combustion chamber. This is important because it allows the air to mix properly with fuel and ensures efficient combustion. By reducing the velocity, the diffuser helps to increase the pressure of the air, which is necessary for the engine to function effectively.
3.
An aircraft taxiing at a constant speed is an example of
Correct Answer
B. Newton's First Law of Motion
Explanation
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 at rest or moving at a constant velocity will continue to do so unless acted upon by an external force. In this case, the aircraft maintains its speed and direction without any changes because there is no net force acting on it.
4.
Foot-pounds and inch-pounds are units of measure for
Correct Answer
A. Work
Explanation
Foot-pounds and inch-pounds are units of measure commonly used to quantify work. Work is defined as the transfer of energy that occurs when a force is applied to an object and it moves in the direction of the force. The units of foot-pounds and inch-pounds represent the amount of work done when a force of one pound is applied over a distance of one foot or one inch, respectively. Therefore, these units are specifically used to measure the amount of work done in mechanical systems.
5.
The resistance of an object to change its motion is a property of matter called
Correct Answer
B. Inertia
Explanation
Inertia is the property of matter that describes its resistance to change in motion. It is the tendency of an object to remain in its current state of motion, whether it is at rest or moving at a constant velocity. This resistance to change in motion is a fundamental characteristic of matter and is not related to energy, friction, or potential.
6.
The ability to do work is the definition of
Correct Answer
A. Energy
Explanation
Energy is defined as the ability to do work. It is a scalar quantity that is associated with objects and systems and is measured in joules. Energy can exist in various forms such as kinetic energy, potential energy, thermal energy, and so on. It is the capacity of a system to perform work or transfer heat. In the context of this question, the correct answer is energy as it aligns with the definition provided.
7.
In a jet engine, fuel is metered for combustion by the
Correct Answer
C. Fuel control
Explanation
The fuel control in a jet engine is responsible for metering the fuel for combustion. It regulates the flow of fuel to ensure the optimal fuel-air mixture is achieved for efficient combustion. The fuel control takes into account various factors such as engine speed, altitude, and power demand to adjust the fuel flow accordingly. It plays a crucial role in maintaining engine performance and fuel efficiency.
8.
The average percentage of a jet engine's energy required to maintain engine operation is
Correct Answer
B. 60
Explanation
The correct answer is 60. This means that, on average, 60% of a jet engine's energy is needed to maintain engine operation. This suggests that a significant portion of the engine's power is used to keep it running efficiently, leaving the remaining energy to propel the aircraft forward.
9.
What effect does the divergent design of a jet engine diffuser have on pressure?
Correct Answer
A. Increases pressure
Explanation
The divergent design of a jet engine diffuser increases pressure. This is because a divergent design gradually increases the cross-sectional area of the flow path, allowing the air to expand and slow down. As the air slows down, its kinetic energy is converted into pressure energy, resulting in an increase in pressure.
10.
The required velocity for air and gases flowing through a jet engine is
Correct Answer
D. Greater velocity exiting than entering
Explanation
The correct answer is "greater velocity exiting than entering" because in a jet engine, the air and gases need to be accelerated to create thrust. This acceleration is achieved by increasing the velocity of the gases as they pass through the engine. As a result, the velocity of the gases exiting the engine is greater than the velocity at which they entered. This increase in velocity creates a force that propels the aircraft forward.
11.
The velocity of the stream of air that flows through a jet engine reaches its highest point at the
Correct Answer
D. Ejector nozzle
Explanation
The correct answer is the ejector nozzle. In a jet engine, the velocity of the stream of air reaches its highest point at the ejector nozzle. The ejector nozzle is responsible for accelerating the exhaust gases and expelling them at high speeds, creating thrust. This high velocity is achieved through the design and shape of the ejector nozzle, which allows for efficient propulsion of the aircraft.
12.
When two or more turbine wheels are used in a jet engine, what is placed directly in front of each turbine wheel?
Correct Answer
D. Nozzle diapHragm
Explanation
In a jet engine, when two or more turbine wheels are used, 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 section, directing the gases onto the turbine blades for maximum efficiency and power generation. It acts as a guide for the exhaust gases, ensuring that they are properly directed towards the turbine blades to drive the engine.
13.
A jet engine derives its name from the fact that
Correct Answer
D. It uses a exhaust-gas-driven turbine wheel to drive its compressor
Explanation
A jet engine derives its name from the fact that it uses an exhaust-gas-driven turbine wheel to drive its compressor. This means that the engine uses the force of the exhaust gases to spin a turbine, which in turn powers the compressor. The compressor then compresses incoming air, which is mixed with fuel and ignited to create a high-pressure, high-velocity jet of exhaust gases. This jet of gases propels the aircraft forward, providing thrust. Therefore, the name "jet engine" is derived from the use of the exhaust gases to drive the turbine and compressor, which is the key mechanism of the engine.
14.
The three major sections of all jet engines are compressor, combustion, and
Correct Answer
B. Turbine
Explanation
The three major sections of all jet engines are the compressor, combustion, and turbine. The compressor is responsible for compressing incoming air, the combustion section mixes fuel with compressed air and ignites it to produce high-pressure and high-temperature gases, and the turbine extracts energy from the high-pressure gases to drive the compressor and other engine accessories. The exhaust section comes after the turbine and is responsible for expelling the exhaust gases. The diffuser is not one of the major sections of a jet engine.
15.
The condition that rapidly reduces the efficiency of a centrifugal jet engine compressor would be
Correct Answer
C. Pressure pulsations
Explanation
Pressure pulsations can rapidly reduce the efficiency of a centrifugal jet engine compressor. These pressure fluctuations can cause disturbances in the flow of air, leading to turbulence and inefficiencies in the compressor's operation. This can result in decreased performance and increased energy consumption. Therefore, pressure pulsations are a critical factor to consider in maintaining the efficiency of a centrifugal jet engine compressor.
16.
The type of engine that is cheaper to manufacture is the
Correct Answer
D. Centrifugal because of fewer parts
Explanation
The correct answer is centrifugal because of fewer parts. Centrifugal engines have a simpler design compared to axial-flow engines, which require a larger number of components. This complexity in the axial-flow engine's structure increases the manufacturing cost. On the other hand, centrifugal engines have a more straightforward construction, resulting in a lower number of parts needed for their production. Consequently, centrifugal engines are cheaper to manufacture due to their reduced complexity and fewer components.
17.
The percentage of combustion efficiency of a gas turbine is usually between
Correct Answer
D. 95 and 100
Explanation
The percentage of combustion efficiency of a gas turbine is usually between 95 and 100. This means that the turbine is able to convert a high percentage of the fuel's energy into useful work, with minimal energy losses through combustion. A combustion efficiency in this range indicates that the turbine is operating at a high level of efficiency and is effectively utilizing the fuel to generate power.
18.
The term "combustion range" is defined as a jet engine's
Correct Answer
D. Operating temperature zone
Explanation
The term "combustion range" refers to the operating temperature zone of a jet engine. This is the range of temperatures at which the engine is designed to operate efficiently and effectively. It is important for the engine to maintain a specific temperature range in order to ensure proper combustion and performance. This temperature range is carefully controlled and monitored to prevent overheating or damage to the engine components.
19.
The most chemically correct ratio for burning fuel in a combustion chamber is
Correct Answer
C. 15:1
Explanation
The most chemically correct ratio for burning fuel in a combustion chamber is 15:1. This ratio indicates that for every 15 units of air, 1 unit of fuel is required for complete combustion. This ratio ensures that there is enough oxygen present to fully oxidize the fuel, resulting in efficient and clean combustion. A higher fuel-to-air ratio would result in a fuel-rich mixture, leading to incomplete combustion and the release of pollutants. Conversely, a lower ratio would result in excess air, reducing the efficiency of combustion. Therefore, a ratio of 15:1 strikes the right balance for optimal combustion.
20.
The inner and outer surfaces of an annular-type combustion chamber are formed by
Correct Answer
A. Interlocking stainless steel bands
Explanation
The correct answer is interlocking stainless steel bands. The use of interlocking stainless steel bands for the inner and outer surfaces of an annular-type combustion chamber provides a strong and secure construction. The interlocking design ensures that the bands fit together tightly, creating a durable and reliable structure. Stainless steel is chosen for its high strength and heat resistance properties, making it suitable for withstanding the extreme conditions of a combustion chamber. This design allows for efficient combustion and containment of the combustion process within the chamber.
21.
The most common type of fuel nozzle system is the
Correct Answer
A. Pressure-atomizing
Explanation
The most common type of fuel nozzle system is the pressure-atomizing system. This system uses high pressure to atomize the fuel into small particles, allowing for efficient combustion. It is commonly used in applications such as gas turbines and industrial burners. The pressure-atomizing system ensures proper fuel distribution and combustion, resulting in optimal performance and reduced emissions.
22.
Swirl-type fuel nozzles are usually used to provide what type of flame speed?
Correct Answer
B. High
Explanation
Swirl-type fuel nozzles are designed to provide a high flame speed. The swirling motion of the fuel and air mixture inside the nozzle enhances the mixing and combustion process, resulting in a faster and more efficient flame propagation. This high flame speed is beneficial in applications where quick and intense combustion is required, such as in certain industrial processes or high-performance engines.
23.
The three design types of turbines used in jet engines are
Correct Answer
C. Impulse, reaction, and reaction-impulse
Explanation
The correct answer is "impulse, reaction, and reaction-impulse." This answer accurately identifies the three design types of turbines used in jet engines. Impulse turbines are primarily used for low-pressure applications, while reaction turbines are used for high-pressure applications. Reaction-impulse turbines combine both impulse and reaction principles to optimize efficiency and power output.
24.
On some jet engines, the turbine bucket is secured in place by
Correct Answer
D. Lock strips
Explanation
Lock strips are used to secure the turbine bucket in place on some jet engines. This method involves using strips that are tightly fitted and locked into position, preventing the bucket from moving or becoming dislodged during operation. Unlike screws, cables, or lockwire, lock strips provide a more secure and reliable means of fastening the turbine bucket.
25.
The purpose of the exhaust duct is to
Correct Answer
D. Straighten exhaust gas-flow
Explanation
The purpose of the exhaust duct is to straighten the exhaust gas-flow. This means that it is designed to remove any turbulence or irregularities in the flow of exhaust gases, ensuring that they flow in a straight and smooth manner. This is important for efficient and effective exhaust system operation, as straightening the flow helps to reduce back pressure and improve overall performance. Straightening the exhaust gas-flow also helps to minimize noise and improve the overall aesthetics of the exhaust system.
26.
When trimming the exhaust gas temperature (EGT) of some jet engines, the nozzle area is changed by
Correct Answer
A. Mice
27.
One common type of variable-area orifice used on augmenters is the
Correct Answer
C. Segmented flap
Explanation
A common type of variable-area orifice used on augmenters is a segmented flap. This type of orifice consists of multiple flaps that can be adjusted to control the flow of a fluid or gas. By manipulating the position of the flaps, the area of the orifice can be increased or decreased, allowing for precise control over the flow rate. This design is often used in applications where a variable flow rate is required, such as in aircraft engines or industrial processes.
28.
The augmenter component that creates local turbulence and reduces gas velocity is the
Correct Answer
B. Flameholder
Explanation
The flameholder is the component that creates local turbulence and reduces gas velocity. It is designed to stabilize the flame in a combustion system by creating recirculation zones and promoting fuel-air mixing. By disrupting the flow of gases, the flameholder helps to maintain a stable and efficient combustion process.
29.
The Hamilton Standard 54H60-91 propeller is a
Correct Answer
C. Four-bladed, reversible-pitch propeller; 13.5 feet in diameter
Explanation
The correct answer is "four-bladed, reversible-pitch propeller; 13.5 feet in diameter." This is because the Hamilton Standard 54H60-91 propeller is described as having four blades and a reversible-pitch mechanism, meaning the angle of the propeller blades can be adjusted to control the aircraft's thrust. Additionally, the propeller has a diameter of 13.5 feet, which refers to the length of the circular path traced by the propeller blades.
30.
A method of de-icing a propeller is to use
Correct Answer
C. Electrically heated elements
Explanation
Electrically heated elements are used as a method of de-icing a propeller. These elements are designed to generate heat when an electric current passes through them, which is then used to melt any ice or frost that has formed on the propeller blades. This method is effective in quickly and efficiently removing ice and ensuring safe operation of the propeller. Bleed air, de-icing solution, and exhaust air from the H-1 heater are not mentioned as methods of de-icing a propeller in the given options.
31.
The type of fuel control that uses items such as thermocouples, relays, amplifiers, and solenoids, to help control the engine is
Correct Answer
D. Electrohydromechanical
Explanation
Electrohydromechanical fuel control is the type of fuel control that utilizes various components such as thermocouples, relays, amplifiers, and solenoids to regulate and manage the engine. This type of system combines electrical and hydraulic mechanisms to achieve precise fuel control and optimize engine performance.
32.
Pressurization of the engine fuel system is controlled by the
Correct Answer
D. Pressurizing and dump (P&D) valve
Explanation
The pressurization of the engine fuel system is controlled by the pressurizing and dump (P&D) valve. This valve is responsible for regulating the pressure of the fuel system by increasing or decreasing the flow of fuel. It ensures that the fuel is delivered to the engine at the correct pressure for optimal performance. The P&D valve also allows for the dumping of excess fuel from the system, preventing over-pressurization and potential damage to the engine.
33.
During a visual inspection, how can you tell when a fuel filter is clogged?
Correct Answer
C. A differential pressure indicator is actuated
Explanation
A differential pressure indicator is actuated when a fuel filter is clogged. This means that the pressure difference between the inlet and outlet of the filter becomes significant, triggering the indicator. This is a clear indication that the filter is obstructed and needs to be cleaned or replaced. It provides a visual or audible signal to alert the user that the filter is no longer functioning properly and requires attention.
34.
Classified as to structure, which of the following is not a type of oil pump?
Correct Answer
C. Rotogear
Explanation
The question asks for a type of oil pump that is not classified based on structure. The options provided are gear, gerotor, rotogear, and sliding vane. Gear and gerotor are both types of oil pumps that are classified based on structure. Sliding vane is another type of oil pump that is also classified based on structure. However, "rotogear" is not a recognized type of oil pump, and therefore does not fit into any classification based on structure.
35.
Structurally, the most common type of oil pump in use is the
Correct Answer
D. Gear
Explanation
The most common type of oil pump in use is the gear pump. This type of pump uses two meshing gears to create suction and move the oil through the pump. The gears rotate and create a seal, trapping the oil between the teeth of the gears and the pump housing. As the gears rotate, the oil is carried from the suction side to the discharge side of the pump. Gear pumps are known for their reliability, efficiency, and ability to handle high pressures.
36.
The valve that permits jet engine oil flow in only one direction is the
Correct Answer
B. Check
Explanation
The valve that permits jet engine oil flow in only one direction is the check valve. A check valve allows fluid to flow in one direction and prevents backflow. In the context of a jet engine, it ensures that oil flows in the correct direction to lubricate the engine components and prevents any reverse flow that could lead to damage or malfunction.
37.
The oil cooler that operates on the same principle as an automotive radiator is the
Correct Answer
A. Air/oil
Explanation
The correct answer is air/oil because an air/oil cooler operates on the same principle as an automotive radiator. In this type of cooler, air is used to cool the oil, similar to how air is used to cool the coolant in a car radiator. The air/oil cooler consists of fins or tubes that allow the oil to flow through them while air passes over them, dissipating the heat from the oil. This helps to maintain the optimal temperature of the oil and prevent overheating.
38.
The purpose of an oil-temperature control valve used with air/oil coolers is to
Correct Answer
D. Direct oil around or through cooler
Explanation
The purpose of an oil-temperature control valve used with air/oil coolers is to direct oil around or through the cooler. This valve helps regulate the temperature of the oil by controlling its flow. By directing the oil either around or through the cooler, the valve ensures that the oil reaches the desired temperature for optimal performance and efficiency.
39.
To create a static seal between two stationary parts in the oil system, use
Correct Answer
C. A gasket
Explanation
A gasket is used to create a static seal between two stationary parts in the oil system. It is a mechanical seal that fills the gap between the two parts, preventing leakage of fluids or gases. Gaskets are typically made of materials such as rubber, metal, or composite materials that can withstand the pressure and temperature of the oil system. They are designed to provide a reliable and long-lasting seal, ensuring the proper functioning of the oil system.
40.
The air turbine (impingement) starter used on jet engines
Correct Answer
C. Has the advantages of less weight and fewer moving parts than other starters
Explanation
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 it is lighter and simpler in design compared to alternative starters. This can be beneficial for aircraft as it reduces the overall weight and complexity of the engine system. Additionally, having fewer moving parts can potentially improve reliability and reduce maintenance requirements.
41.
The unit of a jet engine alternating current (AC) ignition system that develops 20,000 volts, delivered to the igniter plugs, is the
Correct Answer
D. Transformer
Explanation
The correct answer is transformer. A transformer is a device that transfers electrical energy between two or more circuits through electromagnetic induction. In the case of a jet engine's AC ignition system, the transformer is responsible for stepping up the voltage from the power source to a high level, such as 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.
42.
A simple direct current (DC) ignition system consists of
Correct Answer
D. Vibrator, igniter plugs, and transformer
Explanation
A simple direct current (DC) ignition system consists of a vibrator, igniter plugs, and a transformer. The vibrator is responsible for creating the alternating current (AC) which is then converted to DC by the AC-to-DC converter. The transformer is used to step up the voltage from the DC source to a higher voltage required for ignition. Finally, the igniter plugs are used to create a spark to ignite the fuel-air mixture in the engine.
43.
An advantage of the high-energy capacitor type jet engine ignition system is it
Correct Answer
D. Makes starting possible when the igniter plugs are fouled
Explanation
The advantage of the high-energy capacitor type jet engine ignition system is that it makes starting possible when the igniter plugs are fouled. This means that even if the igniter plugs become dirty or clogged, the high-energy capacitor type ignition system can still ignite the fuel and start the engine. This is beneficial because it ensures that the engine can still be started even in less than ideal conditions, improving the reliability and performance of the jet engine.
44.
Aircraft engine indicating instruments must
Correct Answer
C. Be light in weight, small in size, and easy to read
Explanation
Aircraft engine indicating instruments need to be light in weight and small in size in order to minimize the overall weight and size of the aircraft, which is crucial for efficient and safe flight. Additionally, the instruments must be easy to read to ensure that pilots can quickly and accurately interpret the information provided by the instruments.
45.
Exhaust gas temperature (EGT) indicators indicate the engine EGT in
Correct Answer
D. Degrees Celcius
Explanation
The exhaust gas temperature (EGT) indicators are used to measure the temperature of the engine's exhaust gases. The temperature is typically measured in degrees Celsius, as indicated by the answer. This measurement is important for monitoring the engine's performance and ensuring that it is operating within safe temperature ranges. The use of degrees Celsius is a common unit of measurement for temperature in many industries, including automotive and engineering.
46.
The three benefits of the Joint Oil Analysis Program (JOAP) are improved safety, reduced maintenance cost, and
Correct Answer
C. Increased equipment availability
Explanation
The Joint Oil Analysis Program (JOAP) provides three benefits, one of which is increased equipment availability. This means that by participating in JOAP, organizations can ensure that their equipment is readily available for use, minimizing downtime and maximizing productivity. This benefit is crucial in industries where equipment downtime can result in significant financial losses. By monitoring oil analysis through JOAP, organizations can identify potential issues or failures in equipment early on, allowing for timely maintenance and repairs, thus increasing equipment availability.
47.
You should not use mouth-suction to take jet engine oil samples because
Correct Answer
A. This could cause paralysis or death
Explanation
Using mouth-suction to take jet engine oil samples is dangerous because it could cause paralysis or death. This method involves sucking the oil into the mouth, which can lead to the ingestion of harmful chemicals or substances present in the oil. These substances can cause severe health problems or even be fatal. Therefore, it is important to use proper sampling techniques and equipment to ensure the safety of the individual collecting the sample.
48.
The most common contamination found in lubricant systems is
Correct Answer
A. Dirt and sand
Explanation
The most common contamination found in lubricant systems is dirt and sand. These particles can enter the system through various means such as air, water, or external sources. Dirt and sand can cause abrasion and wear on the components of the lubricant system, leading to reduced efficiency and potential damage. Regular maintenance and filtration are necessary to remove these contaminants and ensure the proper functioning of the lubricant system.
49.
A well-designed aircraft fuel system will ensure
Correct Answer
D. Positive and reliable fuel-flow under all conditions
Explanation
A well-designed aircraft fuel system should ensure a positive and reliable fuel-flow under all conditions. This means that the system should consistently deliver fuel to the engine in a reliable manner, regardless of the operating conditions or any potential issues that may arise. It is important for the fuel system to maintain a positive flow of fuel to ensure that the engine receives the necessary fuel for proper operation. Additionally, the fuel-flow should be reliable to avoid any interruptions or failures in the fuel supply, which could lead to engine malfunctions or loss of power.
50.
The three types of shutoff valves used in the crossfeed fuel system are the
Correct Answer
C. Sliding gate, rotary plug, and disc
Explanation
The correct answer is sliding gate, rotary plug, and disc. These three types of shutoff valves are commonly used in the crossfeed fuel system. The sliding gate valve is designed to regulate the flow of fuel by sliding a gate across the fuel passage. The rotary plug valve uses a rotating plug to control the fuel flow. The disc valve, on the other hand, utilizes a disc that can be rotated to open or close the fuel passage. Together, these three types of valves provide effective control and regulation of fuel flow in the crossfeed fuel system.