# 2A651 Volume 2 Ure's

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2a651 Volume 2 ure's

• 1.

### An aircraft taxiing at a steady speed can be used to demonstrate?

• A.

Bernoulli's principle

• B.

Newton's first law of motion

• C.

Newton's second law of motion

• D.

Newton's third law of motion

B. Newton's first law of motion
Explanation
An aircraft taxiing at a steady speed can be used to demonstrate Newton's first law of motion. Newton's first law states that an object at rest will stay at rest, and an object in motion will stay in motion with the same speed and in the same direction unless acted upon by an external force. In this case, the aircraft is in motion and continues to move at a steady speed unless a force, such as friction or wind resistance, acts upon it.

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• 2.

### Which law may you sum up with two words: action and reaction?

• A.

Bernoulli's principle

• B.

Newton's first law of motion

• C.

Newton's second law of motion

• D.

Newton's third law of motion

D. Newton's third law of motion
Explanation
Newton's third law of motion states that for every action, there is an equal and opposite reaction. This means that any force exerted on an object will result in an equal force exerted in the opposite direction. In other words, if an object pushes or pulls on another object, the second object will push or pull back with the same amount of force. This law can be summed up with the words "action" and "reaction" because it describes the relationship between the two forces.

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• 3.

### Which type of duct would decrease the velocity and increase the pressure of a gas as it passes through?

• A.

Elbow

• B.

Straight

• C.

Divergent

• D.

Convergent

C. Divergent
Explanation
A divergent duct would decrease the velocity and increase the pressure of a gas as it passes through. This is because a divergent duct gradually increases in size, causing the gas to spread out and slow down. As the gas slows down, its pressure increases. Therefore, a divergent duct is designed to decrease velocity and increase pressure.

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• 4.

### The ability to do work is the definition of?

• A.

Energy

• B.

Inertia

• C.

Friction

• D.

Velocity

A. Energy
Explanation
Energy is defined as the ability to do work. It is a fundamental concept in physics and refers to the capacity of a system or object to perform work or transfer heat. In other words, energy is what allows objects to exert force and cause changes in their surroundings. In this context, inertia, friction, and velocity are not the correct definitions of the ability to do work.

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• 5.

### What does fuel for an engine represent?

• A.

Thrust produced

• B.

Efficieny ratio

• C.

Potential energy

• D.

Availble horsepower

C. Potential energy
Explanation
Fuel for an engine represents potential energy. Potential energy is the stored energy within a system that can be converted into other forms of energy, such as kinetic energy or thermal energy. In the case of an engine, fuel contains potential energy that is released through combustion, converting it into mechanical energy to power the engine. This potential energy is harnessed and utilized to generate thrust, efficiency, and available horsepower, making it the most appropriate choice among the given options.

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• 6.

### The temperature of compressed air in a jet engine must be raised to?

• A.

Increase energy

• B.

Decrease energy

• C.

Increase volume

• D.

Decrease volume

A. Increase energy
Explanation
The temperature of compressed air in a jet engine must be raised to increase energy. This is because increasing the temperature of the air increases its kinetic energy, which in turn increases the energy available for propulsion. By raising the temperature, the air molecules move faster and collide with more force, resulting in a greater thrust produced by the engine. This increase in energy is essential for the efficient functioning of the jet engine and to generate the necessary power for the aircraft to take off and maintain flight.

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• 7.

### Which section of a jet engine introduction and burns fuel?

• A.

Turbine

• B.

Diffuser

• C.

Compressor

• D.

Combustion

D. Combustion
Explanation
The correct answer is combustion. In a jet engine, the combustion section is responsible for burning the fuel. This is where the fuel is mixed with air and ignited, producing a high-temperature and high-pressure gas that expands and provides the necessary thrust to propel the aircraft forward. The combustion process is essential in converting the chemical energy of the fuel into mechanical energy, which powers the engine and enables flight.

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• 8.

### Which method of producing thrust does a turboprop engine use?

• A.

Using only the energy expended through the exhaust nozzle to propel the aircraft forward

• B.

Using the same working fluid for propulsive force as that used within the engine

• C.

Accelerating a large mass of air through a small velocity change

• D.

Moving a small quantity of air through a large velocity change

C. Accelerating a large mass of air through a small velocity change
Explanation
A turboprop engine uses the method of accelerating a large mass of air through a small velocity change to produce thrust. This means that the engine uses a propeller to move a large amount of air at a relatively low speed, resulting in a small change in velocity but a significant amount of thrust. This method is efficient for aircraft that operate at lower speeds and require a high level of fuel efficiency.

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• 9.

### Which type of horsepower is delivered to the propeller for useful work?

• A.

Brake

• B.

Indicated

• C.

Frictional

• D.

Equivalent shaft

A. Brake
Explanation
The type of horsepower that is delivered to the propeller for useful work is brake horsepower. Brake horsepower refers to the actual power output of an engine or motor, measured at the output shaft. It represents the power available for doing useful work, such as turning the propeller in this case, after accounting for losses due to friction and other factors.

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• 10.

### Which type of horsepower determines the performance of the engine-propeller combination?

• A.

Brake

• B.

Indicated

• C.

Frictional

• D.

Equivalent shaft

D. Equivalent shaft
Explanation
The type of horsepower that determines the performance of the engine-propeller combination is the equivalent shaft horsepower. This measure takes into account the power output of the engine and how efficiently it is transferred to the propeller. It considers factors such as mechanical losses and the efficiency of the propeller in converting the power into thrust. By using equivalent shaft horsepower, one can accurately assess the overall performance of the engine-propeller combination.

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• 11.

### The two fluids combined to make up common jet fuel are?

• A.

Gasoline and oil

• B.

Kerosene and oil

• C.

Gasoline and water

• D.

Kerosene and gasoline

D. Kerosene and gasoline
Explanation
Jet fuel is a specific type of fuel used in aircraft engines. It is a mixture of kerosene and gasoline. Kerosene provides the necessary energy and stability for the engine, while gasoline helps to improve the fuel's performance in extreme temperatures. This combination ensures that the fuel can withstand the high temperatures and pressures inside the aircraft engine, allowing for efficient and safe operation during flight.

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• 12.

### Which is not a method of heat transfer?

• A.

• B.

Convection

• C.

Penetration

• D.

Conduction

C. Penetration
Explanation
Penetration is not a method of heat transfer. Radiation, convection, and conduction are the three main methods of heat transfer. Radiation refers to the transfer of heat through electromagnetic waves, such as the heat we receive from the sun. Convection is the transfer of heat through the movement of fluids or gases, like the way heat is transferred in boiling water. Conduction is the transfer of heat through direct contact between objects, such as when a metal spoon becomes hot when placed in a hot liquid. Penetration, on the other hand, is not a recognized method of heat transfer.

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• 13.

### The air temperature of a jet engine gradually rises across the compressor to the diffuser outlet as a result of?

• A.

Compression

• B.

Fuel expansion

• C.

Turbine discharge

• D.

Ambient temperature increase

A. Compression
Explanation
The correct answer is compression. As the air passes through the compressor of a jet engine, it is compressed, which causes an increase in temperature. This compression is achieved by using rotating blades to increase the pressure of the air, leading to a rise in temperature. Therefore, the air temperature gradually rises across the compressor to the diffuser outlet as a result of compression.

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• 14.

### Where is the highest point of temperature reached in an engine?

• A.

Tailpipe

• B.

Exhaust cone

• C.

Turbine section

• D.

Combustion section

D. Combustion section
Explanation
The highest point of temperature is reached in the combustion section of an engine. This is where the fuel and air mixture is ignited and combustion occurs, generating a high amount of heat and energy. The combustion section is designed to withstand and control these high temperatures, ensuring efficient combustion and power generation in the engine.

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• 15.

### Which engine component meters fuel for combustion?

• A.

P&D valve

• B.

Fuel pump

• C.

Fuel control

• D.

Fuel nozzles

C. Fuel control
Explanation
The fuel control is responsible for metering fuel for combustion in an engine. It regulates the flow of fuel to ensure the correct amount is delivered to the combustion chamber. This component plays a crucial role in maintaining the proper fuel-to-air ratio for efficient combustion and optimal engine performance. The other options listed, such as the P&D valve, fuel pump, and fuel nozzles, are not directly involved in metering fuel for combustion.

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• 16.

### What happens to the energy that is absorbed by the turbine wheel?

• A.

50 percent is used for accessories

• B.

60 percent is used for accessories

• C.

The energy operates the anti-ice system

• D.

The energy is returned to the compressor

D. The energy is returned to the compressor
Explanation
The energy that is absorbed by the turbine wheel is returned to the compressor. This means that the energy is not lost or wasted, but rather recycled back into the system to be used again. By returning the energy to the compressor, it can be used to continue the cycle of generating power and driving the turbine. This ensures maximum efficiency and utilization of the energy in the system.

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• 17.

### On an average, what percent of all the energy produced by the fuel is required to maintain the engine operating cycle?

• A.

50

• B.

60

• C.

70

• D.

80

B. 60
Explanation
The correct answer is 60. This means that, on average, 60% of all the energy produced by the fuel is required to maintain the engine operating cycle. This suggests that a significant amount of energy is needed to keep the engine running efficiently and effectively.

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• 18.

### What directs the gases onto the first-stage turbine wheel blades in a jet engine?

• A.

• B.

Combustion chamber

• C.

Turbine stator

• D.

Flameholder

C. Turbine stator
Explanation
The turbine stator directs the gases onto the first-stage turbine wheel blades in a jet engine. The stator is a stationary component that is located between the combustion chamber and the turbine wheel. Its purpose is to guide and direct the flow of hot gases from the combustion chamber onto the turbine blades. By controlling the flow of gases, the stator helps to optimize the efficiency and performance of the turbine, ultimately contributing to the overall operation of the jet engine.

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• 19.

### A jet engine derives its name from its design in that it uses?

• A.

Turbo-superchargers within the engine

• B.

A turbine-type compressor to maintain power

• C.

Nozzles which are called jets within the engine

• D.

A gas-driven turbine wheel to drive its compressor

D. A gas-driven turbine wheel to drive its compressor
Explanation
A jet engine uses a gas-driven turbine wheel to drive its compressor. This means that the engine has a turbine wheel that is powered by the flow of hot gases, which in turn drives the compressor. The compressor then compresses the incoming air, which is mixed with fuel and ignited, creating the necessary thrust for the jet engine to propel an aircraft forward. This design allows the engine to generate the power needed for flight by utilizing the energy from the gas-driven turbine wheel.

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• 20.

### Vane-type fuel pumps used in jet engines are similar to?

• A.

Sliding-vane air compressors

• B.

Piston pump air compressors

• C.

Roots air compressors

• D.

Turbo-superchargers

A. Sliding-vane air compressors
Explanation
Vane-type fuel pumps used in jet engines are similar to sliding-vane air compressors. Both types of pumps use a set of vanes that slide in and out of slots in a rotor to create a pumping action. This design allows for a smooth and continuous flow of fuel or air, making it efficient and reliable. The sliding-vane mechanism also helps to reduce noise and vibration, making it suitable for use in jet engines where precision and quiet operation are crucial.

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• 21.

### Which condition reduces the efficiency of a centrifugal compressor?

• A.

Resultant velocity

• B.

Tangential velocity

• C.

Pressure pulsations

• D.

Air mass leaving the impeller at great velocities

C. Pressure pulsations
Explanation
Pressure pulsations can reduce the efficiency of a centrifugal compressor. These pulsations occur when there are fluctuations in the pressure of the compressed air, causing uneven flow and turbulence within the compressor. This can lead to increased energy losses and decreased overall efficiency of the compressor.

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• 22.

### Stationary vanes positioned between rotor discs in a compressor are used to?

• A.

Direct air and increase pressure

• B.

Direct hot gases rearward

• C.

Increase backup pressure

• D.

Prolong compressor life

A. Direct air and increase pressure
Explanation
Stationary vanes positioned between rotor discs in a compressor are used to direct air and increase pressure. These vanes act as a guide for the airflow, ensuring that it flows in the desired direction and is compressed effectively. By directing the air, the vanes help to increase the pressure within the compressor, which is essential for efficient operation. This allows the compressor to generate higher pressure levels, which are often necessary for various industrial processes and applications.

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• 23.

### The jet engine compressor that is cheaper to manufacture is the?

• A.

Axial-flow type, because of its size

• B.

Centrifugal type, because of its size

• C.

Axial-flow type, because of its fewer parts.

• D.

Centrifugal type, because of its fewer parts

D. Centrifugal type, because of its fewer parts
Explanation
The correct answer is centrifugal type, because of its fewer parts. The centrifugal type of jet engine compressor is cheaper to manufacture because it has fewer parts compared to the axial-flow type. This means that there are fewer components that need to be manufactured, assembled, and maintained, resulting in lower production costs. Additionally, the simplicity of the centrifugal compressor design allows for easier manufacturing processes, further reducing costs.

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• 24.

### The precentage of combustion efficiency of a gas turbine is usually between?

• A.

60 and 70

• B.

65 and 75

• C.

75 and 95

• D.

95 and 100

D. 95 and 100
Explanation
Gas turbine combustion efficiency refers to the ratio of the heat energy produced by the combustion process to the energy input from the fuel. A high combustion efficiency indicates that a greater percentage of the fuel's energy is being converted into useful work. Therefore, a gas turbine's combustion efficiency is typically expected to be between 95 and 100 percent, as this range represents a highly efficient and effective combustion process.

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• 25.

### What is the most probable cuase of a flameout of a jet engine flying at 40,000 feet with a constant engine rpm of 50 percent?

• A.

The rpm is too low

• B.

A decrease in barometric pressure

• C.

The failure of the breather pressurizing valve

• D.

Excessive ducting of air from the compressor into the combustion chamber

A. The rpm is too low
Explanation
The most probable cause of a flameout of a jet engine flying at 40,000 feet with a constant engine rpm of 50 percent is that the rpm is too low. When the engine rpm is too low, there may not be enough fuel-air mixture in the combustion chamber for the engine to sustain combustion, leading to a flameout.

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• 26.

### Carbon monoxide gas is poisonous and odorless, and has

• A.

A reddish color

• B.

A greenish color

• C.

A yellowish color

• D.

no color

D. no color
Explanation
Carbon monoxide gas is poisonous and odorless, which means it cannot be detected by smell. Additionally, it does not have any color, making it difficult to visually identify. This lack of color is one of the reasons why carbon monoxide can be so dangerous, as it can go unnoticed and easily be inhaled without any warning signs.

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• 27.

### What is the most chemically correct ratio for burning fuel in a combustion chamber?

• A.

10:1

• B.

10:4

• C.

15:1

• D.

15:4

C. 15:1
Explanation
The most chemically correct ratio for burning fuel in a combustion chamber is 15:1. This means that for every 15 parts of air, there is 1 part of fuel. This ratio ensures that there is enough oxygen present to completely burn the fuel, resulting in efficient combustion and minimal emissions. A ratio of 15:1 provides the ideal balance between fuel and air, maximizing energy release while maintaining a stable and controlled combustion process.

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• 28.

### The inner and outer surfaces of an annular-type combustion chamber are formed by?

• A.

Interlocking stainless-steel bands

• B.

The inner and outer diffuser case

• C.

A forged steel casing

• D.

Solid sheet metal

A. Interlocking stainless-steel bands
Explanation
The correct answer is interlocking stainless-steel bands. In an annular-type combustion chamber, the inner and outer surfaces are formed by interlocking stainless-steel bands. This design allows for better heat resistance and structural integrity, as the interlocking bands provide support and prevent the combustion chamber from expanding or deforming under high temperatures and pressures. The use of stainless steel also ensures corrosion resistance and durability, making it suitable for the harsh conditions of a combustion chamber.

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• 29.

### Fuel that accumulates after a failed start is?

• A.

Returned to the fuel control

• B.

Drained overboard by a drain system

• C.

Burned on the next start attempt

• D.

Allowed to evaporate

B. Drained overboard by a drain system
Explanation
After a failed start, the fuel that accumulates needs to be removed from the system to prevent any potential issues. This is done by draining the fuel overboard using a drain system. This ensures that any excess fuel is safely removed from the aircraft and does not interfere with the next start attempt or cause any damage to the fuel control system.

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• 30.

### The parts on a can-annular combustion section must be removed in a specific order because of the?

• A.

Fuel nozzle

• B.

Transition liner

• C.

Combustion chamber outer cases

• D.

Combustion chamber crossover tubes

D. Combustion chamber crossover tubes
Explanation
The combustion chamber crossover tubes must be removed in a specific order because they connect the different combustion chambers within the can-annular combustion section. Removing them in the wrong order could disrupt the flow of fuel and air, leading to inefficient combustion and potential damage to the engine.

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• 31.

### What is the most common type of fuel nozzle system?

• A.

Pressure-atomizing

• B.

Fuel-blasting

• C.

Fuel ejector

• D.

Fuel tube

A. Pressure-atomizing
Explanation
The most common type of fuel nozzle system is the pressure-atomizing system. In this system, fuel is forced through a small nozzle at high pressure, which breaks it up into fine droplets. This allows for efficient combustion and better fuel atomization, resulting in improved fuel efficiency and reduced emissions. The pressure-atomizing system is widely used in various applications, including automotive engines, industrial burners, and aircraft engines.

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• 32.

### What type of flame speed are swirl-type fuel nozzles normally used to provide?

• A.

High

• B.

Low

• C.

Medium

• D.

Medium-high

A. High
Explanation
Swirl-type fuel nozzles are typically used to provide a high flame speed. The swirling motion created by these nozzles helps in better fuel-air mixing, resulting in a more efficient combustion process. This increased flame speed leads to a higher heat release rate, which is beneficial in applications where rapid and intense combustion is required, such as in industrial furnaces or certain types of engines.

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• 33.

### What is placed in front of the rotating blades in a multiple-stage turbine engine?

• A.

Rotating vanes

• B.

Inlet guide vanes

• C.

Turbine rotating nozzles

• D.

Turbine nozzle vane assembly

D. Turbine nozzle vane assembly
Explanation
The turbine nozzle vane assembly is placed in front of the rotating blades in a multiple-stage turbine engine. This assembly helps to control the flow of gases and directs them onto the rotating blades, increasing the efficiency of the turbine. The vanes in the assembly are designed to guide the gases and optimize their energy transfer to the blades, resulting in enhanced power output.

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• 34.

### The "fir tree" method of attaching turbine blades (buckets) to the turbine rotor disc is preferred because?

• A.

Of the temperature differential between the turbine rotor disc and the blades

• B.

It aids in preventing horizontal movement of the blades

• C.

There is more blade tip shake during engine operation

• D.

It aids in preventing axial movement of the bucket

A. Of the temperature differential between the turbine rotor disc and the blades
Explanation
The "fir tree" method of attaching turbine blades to the turbine rotor disc is preferred because of the temperature differential between the turbine rotor disc and the blades. This method allows for a secure and tight fit between the blades and the disc, preventing any movement or loosening of the blades due to the expansion and contraction caused by the temperature difference. This ensures the efficient and safe operation of the turbine.

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• 35.

### Which method of attaching the turbine blades (buckets) to the turbine rotor disc is used most frequently?

• A.

Turbine blades fitted solidly into the rim of the rotor disc

• B.

Rivet placed in a hole through the base of the turbine blade

• C.

Close-fitting shroud ring around the outer perimeter of the disc

• D.

Series of grooves or notches broached in the rim of the turbine rotor disc

D. Series of grooves or notches broached in the rim of the turbine rotor disc
Explanation
The most frequently used method of attaching turbine blades to the turbine rotor disc is by using a series of grooves or notches broached in the rim of the disc. This method provides a secure and reliable connection between the blades and the disc, allowing for efficient power transfer and minimizing the risk of blade detachment during operation. Additionally, the use of grooves or notches allows for easy replacement of individual blades if necessary, without requiring the entire disc to be replaced.

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• 36.

### The exhaust duct connects the turbine outlet and the?

• A.

Fan duct

• B.

Jet nozzle

• C.

Fuel nozzle

• D.

Bifurcated duct

B. Jet nozzle
Explanation
The exhaust duct connects the turbine outlet to the jet nozzle. The jet nozzle is responsible for accelerating the exhaust gases expelled from the turbine, thereby generating thrust for the aircraft. It is a crucial component in the propulsion system, as it controls the flow and velocity of the exhaust gases, allowing for efficient and effective propulsion.

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• 37.

### The purpose of the exhaust duct is to?

• A.

Swirl exhaust gas-flow

• B.

Equalize exhaust gas-flow

• C.

Straighten exhaust gas-flow

• D.

Modulate exhaust gas-flow

C. Straighten exhaust gas-flow
Explanation
The purpose of the exhaust duct is to straighten the exhaust gas-flow. This means that the duct is designed to ensure that the gas flows in a straight and smooth manner without any obstructions or turbulence. Straightening the gas-flow helps to improve the efficiency of the exhaust system and allows the gases to be expelled more effectively.

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• 38.

### Which component in the augmentor creates local turbulence and reduces gas velocity?

• A.

Spraybars

• B.

Flameholder

• C.

Screech liner

• D.

Fuel manifold

B. Flameholder
Explanation
The flameholder is the component in the augmentor that creates local turbulence and reduces gas velocity. It is designed to stabilize the flame and enhance combustion efficiency. By disrupting the flow of gases, the flameholder promotes mixing and ensures that the fuel-air mixture is thoroughly burned. This turbulence helps to maintain a stable flame and prevent flame blowout.

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• 39.

### How many different type of loads can be imposed on a jet engine bearing?

• A.

Two

• B.

Three

• C.

Four

• D.

Five

B. Three
Explanation
There are three different types of loads that can be imposed on a jet engine bearing.

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• 40.

### before inspecting new jet engine bearings, you should?

• A.

Separate the halves

• B.

Perform a spin check

• C.

Apply a preservative coating

• D.

Remove a preservative coating

D. Remove a preservative coating
Explanation
Before inspecting new jet engine bearings, you should remove a preservative coating. This is because new bearings are typically coated with a preservative to protect them during storage and transportation. Removing this coating allows for a thorough inspection of the bearings to ensure they are in proper condition before being installed in the engine.

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• 41.

### The most commonly  used bearing removal tools include?

• A.

Drift pipes and hammers

• B.

Bearing pullers and hammers

• C.

Drift pipes and arbor presses

• D.

Arbor presses and bearing pullers

D. Arbor presses and bearing pullers
Explanation
Arbor presses and bearing pullers are the most commonly used tools for removing bearings. Arbor presses are used to apply pressure to push the bearing out of its housing, while bearing pullers are used to grip and pull the bearing out. These tools are specifically designed for bearing removal and are effective in safely and efficiently extracting bearings from their assemblies. The other options, such as drift pipes and hammers, may also be used in some cases, but arbor presses and bearing pullers are the preferred and more commonly used tools.

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• 42.

### Which type of defect appears on bearings as a result of bearing parts striking together?

• A.

Nicks

• B.

Galling

• C.

Grooves

• D.

Scratches

A. Nicks
Explanation
Nicks are a type of defect that appears on bearings as a result of bearing parts striking together. These nicks are small chips or dents that can occur on the surface of the bearing due to excessive force or impact. They can lead to increased friction, reduced performance, and ultimately, failure of the bearing. Nicks are typically caused by improper handling, installation, or maintenance of the bearing.

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• 43.

### Which type of defect appears on bearings as a result of small particles of foreign material becoming lodged between the rollers?

• A.

Pits

• B.

Bands

• C.

Grooves

• D.

Brinelling

C. Grooves
Explanation
When small particles of foreign material become lodged between the rollers of a bearing, it can lead to the formation of grooves. These grooves are a type of defect that can occur on the surface of the bearing. The presence of these grooves can cause uneven wear and tear on the bearing, leading to reduced performance and potentially causing the bearing to fail prematurely. Therefore, grooves are a common type of defect that can occur due to the presence of foreign particles in bearings.

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• 44.

### Which type of bearing defect results  from inadequate lubrication?

• A.

Bands

• B.

Galling

• C.

Grooves

• D.

Brinelling

B. Galling
Explanation
Galling is a type of bearing defect that occurs due to inadequate lubrication. When there is not enough lubrication between the moving parts of a bearing, friction and heat increase, leading to metal-to-metal contact. This causes the surfaces to seize and tear, resulting in galling. Galling can cause damage to the bearing and result in reduced efficiency and premature failure.

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• 45.

### Before you install separable bearings, you must ensure the?

• A.

Rollers are servicable

• B.

Bearings are a matched set

• C.

Rollers are properly positioned

• D.

Parts are positioned and serviceable

B. Bearings are a matched set
Explanation
Before installing separable bearings, it is important to ensure that the bearings are a matched set. This means that the bearings should be of the same size, type, and design. Using mismatched bearings can lead to uneven load distribution, increased friction, and premature wear, which can ultimately result in bearing failure. Therefore, it is crucial to verify that the bearings are a matched set before installation to ensure optimal performance and longevity.

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• 46.

### Of the following, the recommended method of expanding a bearing race before installation is to use a?

• A.

Hot-oil-bath

• B.

Coal furnace

• C.

Hydraulic-oil-bath

• D.

Oscillating heater

A. Hot-oil-bath
Explanation
The recommended method of expanding a bearing race before installation is to use a hot-oil-bath. This is because heating the bearing race in a hot-oil-bath helps to expand the metal, making it easier to fit onto the shaft or housing. The hot oil provides even heating and allows for controlled expansion, ensuring a proper fit and preventing damage to the bearing race during installation.

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• 47.

### Which component reduces the engine rotor speed to the revolutions per minute(rpm) required for accessories?

• A.

step motors

• B.

Reduction motor

• C.

Reduction geartrain

• D.

Gear case drive assembly

C. Reduction geartrain
Explanation
The reduction geartrain is responsible for reducing the engine rotor speed to the required revolutions per minute (rpm) for accessories. This component is designed to decrease the rotational speed and increase the torque output, allowing the engine to efficiently power the various accessories in a vehicle. By utilizing gears of different sizes, the reduction geartrain effectively lowers the speed of the engine rotor, ensuring that the accessories receive the appropriate rpm for their operation.

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• 48.

### The reduction gearbox on an f100-pw-220 engine reduces speed between the main fuel gear pump and the engine-driven main gearbox by?

• A.

45 percent

• B.

33 percent

• C.

46 percent

• D.

52 percent

D. 52 percent
Explanation
The correct answer is 52 percent. The reduction gearbox on an F100-PW-220 engine reduces the speed between the main fuel gear pump and the engine-driven main gearbox by 52 percent. This reduction in speed is necessary to optimize the engine's performance and ensure that the fuel is delivered at the appropriate rate to the engine.

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• 49.

### To cause an accessory in a jet engine to operate at its most optimum speed, design engineers must?

• A.

Change the gear ratio

• B.

Change the govenor settings

• C.

Install an additional set of drive gears

• D.

Adjust the operating speed of the engine

A. Change the gear ratio
Explanation
To cause an accessory in a jet engine to operate at its most optimum speed, design engineers must change the gear ratio. This is because the gear ratio determines the relationship between the speed of the engine and the speed at which the accessory operates. By adjusting the gear ratio, engineers can ensure that the accessory operates at the desired speed, maximizing its efficiency and performance. Changing the governor settings or adjusting the operating speed of the engine may not directly impact the speed of the accessory, while installing an additional set of drive gears may not be necessary if the desired speed can be achieved by simply changing the gear ratio.

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• 50.

### On a f108 engine, which component serves as the mechanical coupling between the compressor rotor and the transfer gearbox(TGB)?

• A.

Power take-off (PTO) drive shaft

• B.

Accessory gearbocx (AGB)

• C.

Inlet gearbox (IGB)

• D.

C. Inlet gearbox (IGB)
Explanation
The correct answer is the inlet gearbox (IGB). The inlet gearbox serves as the mechanical coupling between the compressor rotor and the transfer gearbox (TGB) in an F108 engine. It is responsible for transmitting power from the compressor rotor to the TGB, allowing for the transfer of power and torque between the two components. The other options, such as the power take-off (PTO) drive shaft, accessory gearbox (AGB), and radial drive shaft, do not serve this specific function in the engine.

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• Current Version
• Mar 20, 2023
Quiz Edited by
ProProfs Editorial Team
• Sep 25, 2012
Quiz Created by
Hamandcheese

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