2A551 CDCs Volume 3 Of 3 Ure Questions Only

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1. Oxygen is described as being

Explanation

Oxygen is described as being tasteless because it does not have a distinct flavor. It is colorless because it does not have any visible hue. It is odorless because it does not have any discernible smell.

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About This Quiz
2A551 CDCs Volume 3 Of 3 Ure Questions Only - Quiz

This quiz assesses knowledge on jet engine mechanics, focusing on concepts like air temperature, air velocity, Newton's laws, and basic physics properties such as work and energy. It is designed for individuals preparing for the 2A551 CDCs Volume 3 certification, enhancing understanding of aerospace engineering principles.

2. You should not use mouth-suction to take jet engine oil samples because

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.

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3. The required velocity for air and gases flowing through a jet engine is

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.

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4. The valve that permits jet engine oil flow in only one direction is the

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.

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5. The ability to do work is the definition of

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.

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6. The most common contamination found in lubricant systems is

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.

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7. The arrow stamped on the body of a fuel system check valve indicates the

Explanation

The arrow stamped on the body of a fuel system check valve indicates the direction of free flow. This means that the arrow shows the path through which the fuel can flow freely without any restrictions. It helps in ensuring that the fuel flows in the correct direction and prevents any backflow or blockages in the system.

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8. A well-designed aircraft fuel system will ensure

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.

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9. A liquid fire extinguisher agent douses a fire by

Explanation

A liquid fire extinguisher agent douses a fire by removing oxygen from the area. When the liquid is sprayed onto the fire, it undergoes a process called vaporization, where it turns into a fine mist vapor. This vapor displaces the oxygen surrounding the fire, creating an oxygen-deficient environment. Since fire requires oxygen to sustain combustion, removing oxygen effectively extinguishes the fire. The other options, such as releasing nitrogen or dispersing a heavy concentration of liquid, may not be as effective in extinguishing the fire as removing oxygen.

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10. The disadvantage of a continuous-flow oxygen regulator is it

Explanation

A continuous-flow oxygen regulator is a device used to regulate the flow of oxygen to a patient. The disadvantage of this type of regulator is that it wastes oxygen. This means that more oxygen is being delivered than is actually needed by the patient, resulting in unnecessary waste. This can be problematic, especially in situations where oxygen supply is limited or costly. Therefore, the wastage of oxygen is a significant drawback of a continuous-flow oxygen regulator.

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11. To create a static seal between two stationary parts in the oil system, use

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.

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12. Aircraft engine indicating instruments must

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.

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13. The basic purpose of the fuel vent system is to

Explanation

The fuel vent system is designed to prevent the rupture or collapse of the fuel tanks. This is important because fuel tanks can be subjected to various pressures and temperatures, which can cause them to expand or contract. If the tanks were to rupture or collapse, it could lead to fuel leakage or even explosions, posing a significant safety risk. The vent system allows for the release of excess pressure or vacuum inside the tanks, ensuring that they remain structurally intact and preventing any potential accidents.

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14. An aircraft taxiing at a constant speed is an example of

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.

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15. The purpose of the exhaust duct is to

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.

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16. The type of fuel control that uses items such as thermocouples, relays, amplifiers, and solenoids, to help control the engine is

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.

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17. During a visual inspection, how can you tell when a fuel filter is clogged?

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.

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18. The minimum distance an aircraft should be parked from a hangar prior to a defueling operation is

Explanation

The minimum distance an aircraft should be parked from a hangar prior to a defueling operation is 50 feet. This distance is necessary to ensure safety during the defueling process. It allows for enough space to prevent any potential accidents or mishaps that may occur during the operation. Keeping a safe distance minimizes the risk of fire or explosion, as well as any damage to the aircraft or the hangar itself. Therefore, 50 feet is the appropriate minimum distance for parking an aircraft before defueling.

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19. When installing air-conditioning ducting, the tool used to ensure alignment and sealing is the

Explanation

A rawhide mallet is used to ensure alignment and sealing when installing air-conditioning ducting because it is a soft-faced hammer that won't damage or dent the ducting material. The rawhide material absorbs the impact and provides a cushioned blow, allowing for precise alignment of the ducting components without causing any damage. Additionally, the rawhide mallet helps to create a tight seal between the ducting sections by applying even pressure, ensuring that there are no gaps or leaks in the system.

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20. The air-conditioning in a cargo aircraft uses a diverter valve to divert air to

Explanation

The air-conditioning in a cargo aircraft uses a diverter valve to divert air to both the flight station and cargo compartments. This ensures that both areas are adequately cooled during the flight. The flight station requires a comfortable temperature for the pilots and crew to work efficiently, while the cargo compartments need to maintain a controlled temperature to protect the cargo being transported. By diverting air to both areas, the air-conditioning system can effectively meet the cooling needs of both the flight station and cargo compartments.

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21. A principle disadvantage of liquid fire extinguishing agents is they

Explanation

Liquid fire extinguishing agents are poisonous or highly toxic. This means that they can be harmful to humans and the environment if not handled properly. They may release toxic fumes or chemicals when used, posing a risk to individuals in the vicinity. Additionally, if these agents are not stored correctly, they can potentially leak or contaminate the surrounding area, causing further harm. Therefore, the toxicity of liquid fire extinguishing agents is a significant disadvantage that needs to be considered when using them.

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22. A steady red light on the fire emergency control handle in a liquid-agent fire extinguishing system indicates

Explanation

A steady red light on the fire emergency control handle in a liquid-agent fire extinguishing system indicates a fire. This means that there is an active fire that requires immediate attention and action. The red light serves as a visual indicator to alert the user that there is a fire and that the fire extinguishing system has been activated or is ready to be activated.

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23. When the pressure in a T-handle liquid fire extinguisher container becomes too low,

Explanation

When the pressure in a T-handle liquid fire extinguisher container becomes too low, the light in the cockpit panel will glow. This indicates that the pressure is below the required level and the extinguisher may not function properly. The glowing light serves as a warning signal for the pilot or crew to take action and refill or replace the extinguisher to ensure its effectiveness in case of a fire emergency.

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24. The action of the outflow valve in a fixed-isobaric, single-differential pressurization system is controlled by

Explanation

The correct answer is regulating control chamber pressure. In a fixed-isobaric, single-differential pressurization system, the action of the outflow valve is controlled by regulating the pressure in the control chamber. This control chamber is responsible for maintaining the desired cabin pressure by adjusting the position of the outflow valve. By regulating the pressure in the control chamber, the system can ensure that the cabin pressure remains constant and at the desired level throughout the flight.

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25. At altitudes between 10,000 and 15,000 feet, the greatest danger from hypoxia is

Explanation

At altitudes between 10,000 and 15,000 feet, the greatest danger from hypoxia is an error in judgment. Hypoxia is a condition caused by a lack of oxygen in the body. At higher altitudes, the air becomes thinner and oxygen levels decrease. This can lead to impaired cognitive function, including poor decision-making and judgment. Therefore, the greatest danger in this situation is making critical errors in judgment that could have serious consequences.

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26. The average percentage of a jet engine's energy required to maintain engine operation is

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.

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27. The purpose of an oil-temperature control valve used with air/oil coolers is to

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.

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28. On some jet engines, the turbine bucket is secured in place by

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.

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29. When trimming the exhaust gas temperature (EGT) of some jet engines, the nozzle area is changed by

Explanation

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30. What characteristic distinguishes the ejector-type fuel pump from other types of fuel pumps?

Explanation

The characteristic that distinguishes the ejector-type fuel pump from other types of fuel pumps is that it contains no moving parts. Unlike other fuel pumps that rely on mechanical components to pump fuel, the ejector-type fuel pump uses the Venturi effect to create a pressure difference and draw fuel into the system. This design eliminates the need for any moving parts, making the ejector-type fuel pump more reliable and less prone to wear and tear.

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31. Another name for the disc type valve in a fuel system is

Explanation

The correct answer is butterfly. The disc type valve in a fuel system is commonly referred to as a butterfly valve. This type of valve consists of a disc that rotates on a shaft to control the flow of fuel. The disc is shaped like a butterfly, hence the name.

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32. All of the following aircraft systems use engine bleed air (EBA) except

Explanation

Engine bleed air (EBA) is used in various aircraft systems for different purposes. Anti-icing systems use EBA to prevent ice formation on critical surfaces of the aircraft. Rain removal systems also utilize EBA to clear the windshield and other windows of rainwater. Air-conditioning systems use EBA to regulate the temperature and pressurization within the aircraft cabin. However, fire extinguishing systems do not require EBA as they use specialized agents or substances to suppress and extinguish fires on board the aircraft.

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33. A depression in the duct wall, wherein the surface of the material isn't cut or removed but the depression has caused sharp bends or creases in the material, is the definition of a

Explanation

A major dent refers to a depression in the duct wall that has caused sharp bends or creases in the material, without cutting or removing the surface of the material.

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34. What does the molecular sieve oxygen generating system (MSOGS) concentrator supply to the OXYGEN regulator control panel?

Explanation

The molecular sieve oxygen generating system (MSOGS) concentrator supplies 93 percent oxygen-enriched gas to the OXYGEN regulator control panel. This means that the gas produced by the MSOGS concentrator is mostly oxygen, with a concentration of 93 percent. This level of oxygen-enrichment is suitable for various medical and industrial applications where a high concentration of oxygen is required.

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35. The characteristic of the fluid used in a liquid coolant system (LCS) that makes it suitable as a coolant for electronic components is its

Explanation

The characteristic of the fluid used in a liquid coolant system (LCS) that makes it suitable as a coolant for electronic components is its nonconductance. This means that the fluid does not conduct electricity, which is important in preventing any electrical short circuits or damage to the electronic components. By using a nonconducting coolant, the risk of electrical damage is minimized, ensuring the safe and efficient cooling of the electronic components in the LCS.

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36. The percentage of combustion efficiency of a gas turbine is usually between

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.

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37. The most chemically correct ratio for burning fuel in a combustion chamber is

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.

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38. The inner and outer surfaces of an annular-type combustion chamber are formed by

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.

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39. The Hamilton Standard 54H60-91 propeller is a

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.

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40. A method of de-icing a propeller is to use

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.

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41. The three benefits of the Joint Oil Analysis Program (JOAP) are improved safety, reduced maintenance cost, and

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.

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42. Foot-pounds and inch-pounds are units of measure for

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.

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43. A jet engine derives its name from the fact that

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.

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44. The condition that rapidly reduces the efficiency of a centrifugal jet engine compressor would be

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.

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45. Pressurization of the engine fuel system is controlled by the

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.

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46. The oil cooler that operates on the same principle as an automotive radiator is the

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.

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47. Bleed air system water separators remove 70 to 85 percent of moisture that accumulates in the conditioned air.  This is a result of

Explanation

The correct answer is rapid expansion. When air is rapidly expanded, its temperature decreases. This causes the moisture in the air to condense and form droplets, which can then be separated and removed by the water separators in the bleed air system.

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48. It is important to raise the air temperature in a jet engine to

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.

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49. The resistance of an object to change its motion is a property of matter called

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.

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50. The term "combustion range" is defined as a jet engine's

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.

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51. Swirl-type fuel nozzles are usually used to provide what type of flame speed?

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.

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52. Malfunctions of a fuel system vent float valve can be caused by

Explanation

Rough handling of the valve during installation can cause malfunctions of a fuel system vent float valve. This is because the valve may be damaged or misaligned during the installation process, leading to improper functioning.

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53. When a compressible flange duct end becomes distorted, the corrective action that should be taken is to

Explanation

When a compressible flange duct end becomes distorted, the corrective action that should be taken is to reshape the duct flange end to its original shape. This means that instead of replacing the entire duct flange ends or using a gasket with the duct ends, the most appropriate solution is to simply reshape the distorted section back to its original shape. This ensures that the duct maintains its proper sealing and functionality without the need for extensive replacements or additional materials.

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54. Frequently used in fire warning systems, the fire detector that has a high-nickel steel rod located along the centerline of a stainless steel tube assembly is called

Explanation

The correct answer is an Iron Fireman switch. This type of fire detector is frequently used in fire warning systems and consists of a high-nickel steel rod located along the centerline of a stainless steel tube assembly. This design allows for efficient detection of fires and prompt activation of the fire alarm system. The Iron Fireman switch is specifically designed to detect heat and smoke, making it an effective tool in fire safety.

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55. You are operationally checking a pressure-demand oxygen regulator.  When you blow into the mask with the diluter toggle set at 100% OXYGEN, you should get 

Explanation

When you blow into the mask with the diluter toggle set at 100% OXYGEN, you should get positive resistance. This means that there should be some resistance or difficulty in blowing into the mask, indicating that the pressure-demand oxygen regulator is functioning correctly. If there was no resistance, it would suggest that there is a problem with the regulator and it is not providing the necessary pressure to deliver oxygen effectively. Continuous flow and oxygen pressure are not the expected outcomes when blowing into the mask, so they can be ruled out as incorrect options.

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56. Air trapped in a liquid coolant system (LCS)

Explanation

When air gets trapped in a liquid coolant system, it creates a low-pressure condition within the system. This low-pressure condition activates the filter delta pressure switch, which in turn forces the thermal modulating valve to close. As a result, the cooling capability of the coolant is reduced. The presence of air in the coolant hampers its ability to effectively absorb and dissipate heat, thereby reducing its cooling capacity.

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57. The type of engine that is cheaper to manufacture is the

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.

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58. The most common type of fuel nozzle system is the

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.

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59. The augmenter component that creates local turbulence and reduces gas velocity is the

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.

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60. The action used by the low-level shutoff valve to prevent  the reverse flow of fuel through the valve is

Explanation

A check valve is used by the low-level shutoff valve to prevent the reverse flow of fuel through the valve. A check valve is a one-way valve that allows fluid to flow in one direction but prevents it from flowing back in the opposite direction. In this case, the check valve ensures that fuel does not flow back through the low-level shutoff valve, maintaining the proper flow direction and preventing any potential accidents or damage.

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61. The maximum circuit resistance within a thermocouple circuit is

Explanation

The maximum circuit resistance within a thermocouple circuit is 5 ohms because any resistance higher than this would result in a significant voltage drop across the resistance, leading to inaccurate temperature measurements. The low resistance allows for a minimal voltage drop, ensuring that the thermocouple can accurately measure the temperature difference. Higher resistance would introduce errors and reduce the sensitivity of the thermocouple circuit.

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62. In a jet engine, the velocity of the air is decreased by the

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.

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63. The three major sections of all jet engines are compressor, combustion, and

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.

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64. The three design types of turbines used in jet engines are

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.

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65. The air-refueling (A/R) receptacle is operated

Explanation

The air-refueling (A/R) receptacle is operated hydraulically, meaning that it uses hydraulic power to perform its function. However, it is controlled electrically, which means that the control signals for the A/R receptacle are transmitted through an electrical system. This indicates that the hydraulic system and the electrical system work together to operate and control the A/R receptacle.

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66. One disadvantage of a sliding gate fuel system valve is that it

Explanation

The correct answer is that a sliding gate fuel system valve cannot withstand extreme pressures. This means that when exposed to high levels of pressure, the valve may fail or become damaged. This can lead to fuel leakage or other safety hazards. It is important for a fuel system valve to be able to handle and regulate the pressure of fuel flow effectively to ensure the proper functioning and safety of the system.

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67. The safety feature that protects liquid oxygen (LOX) containers from excessive pressure caused by leaks in the inner container is the

Explanation

A blowout disc is a safety feature that protects liquid oxygen (LOX) containers from excessive pressure caused by leaks in the inner container. When the pressure inside the container exceeds a certain limit, the blowout disc ruptures, releasing the excess pressure and preventing the container from exploding. This ensures the safety of the surrounding environment and individuals handling the LOX containers.

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68. An advantage of the high-energy capacitor type jet engine ignition system is it

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.

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69. The kind of centrifugal pump is used when a fuel supply is required during periods of negative gravity condition is

Explanation

A dual-impeller centrifugal pump is used when a fuel supply is required during periods of negative gravity condition. This type of pump is designed with two impellers that rotate in opposite directions, creating a balanced flow of fuel. The dual-impeller design ensures a consistent and reliable fuel supply even in situations where gravity is working against the flow. This makes it suitable for applications where fuel needs to be supplied in environments with negative gravity conditions.

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70. The primary purpose of the air pressure regulator in a fuel system is to

Explanation

The primary purpose of the air pressure regulator in a fuel system is to control the amount of pressure entering the fuel tank. This is important because the fuel system requires a specific pressure to operate efficiently. The air pressure regulator ensures that the pressure remains within the desired range by regulating the flow of air into the fuel tank. This helps to maintain a consistent fuel supply and prevent any potential damage or malfunction caused by excessive pressure.

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71. A simple direct current (DC) ignition system consists of

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.

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72. In a direct current (DC), liquid-level fuel indicating system, the wiper contact is positioned on the resistance strip by

Explanation

In a direct current (DC), liquid-level fuel indicating system, the wiper contact is positioned on the resistance strip by the movement of a float in the tanks. The float, which is located in the fuel tanks, moves up and down according to the fuel level. As the float moves, it causes the wiper contact to move along the resistance strip. This movement of the wiper contact allows for the measurement of the fuel level in the tanks. The signals from the amplifier, voltage changes in the indicator circuit, and the amount of bleed air pressure applied to the tank are not directly involved in positioning the wiper contact on the resistance strip.

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73. The direct current (DC) voltage supplied to the lights in a photoelectric circuit is pulsed at a rate of

Explanation

The direct current (DC) voltage supplied to the lights in a photoelectric circuit is pulsed at a rate of 10 Hz. This means that the voltage is being turned on and off 10 times per second. Pulsing the voltage allows for control over the amount of light being emitted by the lights. By pulsing the voltage at a specific frequency, the lights can be dimmed or brightened as desired. In this case, the lights are being pulsed at a rate of 10 Hz, meaning they are turning on and off 10 times per second.

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74. Exhaust gas temperature (EGT) indicators indicate the engine EGT in

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.

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75. Aircraft engine temperature and pressure as it applies to the bleed air system is determined by the

Explanation

The temperature and pressure in an aircraft engine's bleed air system are influenced by the engine throttle setting and the ambient temperature. The throttle setting determines the amount of air and fuel being supplied to the engine, which affects the temperature and pressure of the exhaust gases. The ambient temperature, on the other hand, affects the temperature of the air entering the engine. Therefore, both factors play a role in determining the temperature and pressure in the bleed air system.

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76. Fiberglass fabric duct installations are prevented from swelling when the aircraft climbs to high altitudes by

Explanation

Vent holes are used in fiberglass fabric duct installations to prevent swelling when the aircraft climbs to high altitudes. When the aircraft reaches high altitudes, the air pressure decreases, causing the air inside the ducts to expand. Without vent holes, this expansion could cause the ducts to swell and potentially damage the system. Vent holes allow the excess air to escape, relieving the pressure and preventing swelling. This ensures the proper functioning and integrity of the duct system during high altitude flights.

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77. At no time shall fire extinguishing residue, such as that resulting from the use of CB type or foam type fire extinguishing materials, be allowed to remain on the equipment for a period exceeding

Explanation

Fire extinguishing residue, such as that resulting from the use of CB type or foam type fire extinguishing materials, should not be allowed to remain on the equipment for a period exceeding 4 hours. It is important to promptly clean and remove the residue to prevent any potential damage or corrosion to the equipment. Allowing the residue to remain for a longer period could compromise the functionality and safety of the equipment.

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78. One common type of variable-area orifice used on augmenters is the

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.

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79. The unit of a jet engine alternating current (AC) ignition system that develops 20,000 volts, delivered to the igniter plugs, is the

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.

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80. Engine bleed air (EBA) check valves are installed to

Explanation

Engine bleed air (EBA) check valves are installed to prevent the loss of compressed bleed air. These valves ensure that the high-pressure bleed air from the engines does not escape or leak out of the system. By preventing the loss of compressed bleed air, the check valves help maintain the proper functioning of various aircraft systems that rely on bleed air, such as cabin pressurization, air conditioning, and anti-icing. The check valves act as a barrier, allowing the flow of bleed air in one direction while blocking it in the opposite direction, thus ensuring the efficient and effective operation of the aircraft's systems.

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81. The air turbine (impingement) starter used on jet engines

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.

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82. An H-2 emergency assembly (bailout bottle) supplies oxygen to the user for a maximum of about

Explanation

The correct answer is 10 minutes. An H-2 emergency assembly, also known as a bailout bottle, is designed to supply oxygen to the user in emergency situations. It typically provides oxygen for a maximum of about 10 minutes, giving the user enough time to evacuate or find a safer environment.

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83. Liquid oxygen (LOX) converts to gaseous oxygen (GOX) at an expansion ratio of

Explanation

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84. Fuel system disconnect couplings are used

Explanation

Fuel system disconnect couplings are used to interrupt the flow of fuel or air and prevent the loss of fluid. This means that when these couplings are disconnected, it stops the flow of fuel or air, preventing any leakage or loss of fluid. This is important in situations where the fuel or air needs to be controlled, such as during maintenance or repairs, to ensure safety and prevent any accidents or wastage of resources.

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85. The manual control valve in the variable isobaric pressurization system is used as an alternate when the

Explanation

The manual control valve in the variable isobaric pressurization system is used as an alternate when the cabin pressure controller fails. This means that if the cabin pressure controller malfunctions or stops working, the manual control valve can be used to manually adjust and control the cabin pressure. This ensures that the cabin pressure can still be maintained at the desired level even if the cabin pressure controller is not functioning properly.

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86. The purpose of the pneumatic relay in a cabin pressurization system is to

Explanation

The purpose of the pneumatic relay in a cabin pressurization system is to ensure both outflow valves operate at the same time. This is important because it helps maintain the desired cabin pressure by allowing equal airflow through both valves. By synchronizing the operation of the valves, the pneumatic relay helps prevent any imbalances or inconsistencies in cabin pressurization, ensuring the safety and comfort of the passengers and crew onboard the aircraft.

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87. When two or more turbine wheels are used in a jet engine, what is placed directly in front of each turbine wheel?

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.

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88. Classified as to structure, which of the following is not a type of oil pump?

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.

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89. A primary function of the low-level shutoff valve is to control the flow of fuel

Explanation

The primary function of the low-level shutoff valve is to control the flow of fuel being transferred out of a pressurized tank. This valve is responsible for regulating the amount of fuel that is released from the tank, ensuring that it is done in a controlled manner. By controlling the flow, the valve helps prevent any potential issues or accidents that may arise from an uncontrolled release of fuel.

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90. What effect does the divergent design of a jet engine diffuser have on 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.

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91. Structurally, the most common type of oil pump in use is the

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.

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92. The three types of shutoff valves used in the crossfeed fuel system are the

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.

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93. The fuel subsystem designed to minimize fuel boiling is

Explanation

Pressurization is the correct answer because when the fuel subsystem is pressurized, it helps to prevent fuel boiling. This is important because boiling fuel can cause vapor lock and disrupt the fuel flow, leading to engine failure. By maintaining a certain level of pressure in the fuel system, the boiling point of the fuel is increased, ensuring that it remains in a liquid state and can be effectively delivered to the engine for combustion.

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94. A liquid coolant system (LCS) keeps electronic components cool by

Explanation

The correct answer is cycling coolant through the electronic component. A liquid coolant system is designed to keep electronic components cool by continuously circulating coolant through the component. This allows the coolant to absorb heat from the electronic component and carry it away, preventing overheating and damage to the electronics. Directing coolant across the electronic component or cycling conditioned air through the component may not be as effective in removing heat as liquid coolant, making them incorrect choices.

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95. The velocity of the stream of air that flows through a jet engine reaches its highest point at the

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.

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96. In a jet engine, fuel is metered for combustion by the

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.

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97. The fuel system component used to prevent excessive pressure from building up in trapped lines is the

Explanation

A spring-loaded relief valve is a fuel system component that is used to prevent excessive pressure from building up in trapped lines. It works by using a spring to control the pressure and release it when it reaches a certain level. This helps to protect the fuel system from damage caused by excessive pressure, ensuring that it operates safely and efficiently. The other options, such as the thermal-relief valve, pressure-relief valve, and one-way check valve, may have different functions in the fuel system but do not specifically address the prevention of excessive pressure buildup in trapped lines.

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98. In a molecular sieve oxygen generating system (MSOGS), water droplets from the air are removed by a(n)

Explanation

The MSOGS concentrator inlet filter is the correct answer because it is responsible for removing water droplets from the air in a molecular sieve oxygen generating system. The filter acts as a barrier, allowing only dry air to pass through and preventing any water droplets from entering the system. This is important because water droplets can interfere with the functioning of the molecular sieve bed, which is responsible for separating oxygen from other gases. By removing the water droplets, the concentrator inlet filter ensures the efficient and effective operation of the MSOGS.

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99. The output pressure and the flow ratings of a centrifugal-type fuel pump are greater than the system needs in order to

Explanation

The output pressure and flow ratings of a centrifugal-type fuel pump are greater than the system needs in order to provide an ample supply of fuel in case of a single pump failure. This means that even if one pump fails, the remaining pump(s) can still deliver enough fuel to the engines to keep them running. This redundancy ensures that the aircraft can continue to operate safely and avoid any potential engine failure due to fuel shortage.

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100. If the temperature of the bleed air from a cargo-type air conditioning system's primary heat exchanger exceeds 540 degrees F, the high limit section of the temperature anticipator will

Explanation

When the temperature of the bleed air from a cargo-type air conditioning system's primary heat exchanger exceeds 540 degrees F, the high limit section of the temperature anticipator will close the bleed air regulating and shutoff valve. This is because the high temperature indicates a potential risk of overheating or damage to the system. By closing the bleed air regulating and shutoff valve, the flow of hot air into the system is restricted, helping to prevent any further increase in temperature and ensuring the safety and proper functioning of the air conditioning system.

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Oxygen is described as being
You should not use mouth-suction to take jet engine oil samples...
The required velocity for air and gases flowing through a jet engine...
The valve that permits jet engine oil flow in only one direction is...
The ability to do work is the definition of
The most common contamination found in lubricant systems is
The arrow stamped on the body of a fuel system check valve indicates...
A well-designed aircraft fuel system will ensure
A liquid fire extinguisher agent douses a fire by
The disadvantage of a continuous-flow oxygen regulator is it
To create a static seal between two stationary parts in the oil...
Aircraft engine indicating instruments must
The basic purpose of the fuel vent system is to
An aircraft taxiing at a constant speed is an example of
The purpose of the exhaust duct is to
The type of fuel control that uses items such as thermocouples,...
During a visual inspection, how can you tell when a fuel filter is...
The minimum distance an aircraft should be parked from a hangar prior...
When installing air-conditioning ducting, the tool used to ensure...
The air-conditioning in a cargo aircraft uses a diverter valve to...
A principle disadvantage of liquid fire extinguishing agents is they
A steady red light on the fire emergency control handle in a...
When the pressure in a T-handle liquid fire extinguisher container...
The action of the outflow valve in a fixed-isobaric,...
At altitudes between 10,000 and 15,000 feet, the greatest danger from...
The average percentage of a jet engine's energy required to...
The purpose of an oil-temperature control valve used with air/oil...
On some jet engines, the turbine bucket is secured in place by
When trimming the exhaust gas temperature (EGT) of some jet engines,...
What characteristic distinguishes the ejector-type fuel pump from...
Another name for the disc type valve in a fuel system is
All of the following aircraft systems use engine bleed air (EBA)...
A depression in the duct wall, wherein the surface of the material...
What does the molecular sieve oxygen generating system (MSOGS)...
The characteristic of the fluid used in a liquid coolant system (LCS)...
The percentage of combustion efficiency of a gas turbine is usually...
The most chemically correct ratio for burning fuel in a combustion...
The inner and outer surfaces of an annular-type combustion chamber are...
The Hamilton Standard 54H60-91 propeller is a
A method of de-icing a propeller is to use
The three benefits of the Joint Oil Analysis Program (JOAP) are...
Foot-pounds and inch-pounds are units of measure for
A jet engine derives its name from the fact that
The condition that rapidly reduces the efficiency of a centrifugal jet...
Pressurization of the engine fuel system is controlled by the
The oil cooler that operates on the same principle as an automotive...
Bleed air system water separators remove 70 to 85 percent of moisture...
It is important to raise the air temperature in a jet engine to
The resistance of an object to change its motion is a property of...
The term "combustion range" is defined as a jet engine's
Swirl-type fuel nozzles are usually used to provide what type of flame...
Malfunctions of a fuel system vent float valve can be caused by
When a compressible flange duct end becomes distorted, the corrective...
Frequently used in fire warning systems, the fire detector that has a...
You are operationally checking a pressure-demand oxygen...
Air trapped in a liquid coolant system (LCS)
The type of engine that is cheaper to manufacture is the
The most common type of fuel nozzle system is the
The augmenter component that creates local turbulence and reduces gas...
The action used by the low-level shutoff valve to prevent  the...
The maximum circuit resistance within a thermocouple circuit is
In a jet engine, the velocity of the air is decreased by the
The three major sections of all jet engines are compressor,...
The three design types of turbines used in jet engines are
The air-refueling (A/R) receptacle is operated
One disadvantage of a sliding gate fuel system valve is that it
The safety feature that protects liquid oxygen (LOX) containers from...
An advantage of the high-energy capacitor type jet engine ignition...
The kind of centrifugal pump is used when a fuel supply is required...
The primary purpose of the air pressure regulator in a fuel system is...
A simple direct current (DC) ignition system consists of
In a direct current (DC), liquid-level fuel indicating system, the...
The direct current (DC) voltage supplied to the lights in a...
Exhaust gas temperature (EGT) indicators indicate the engine EGT in
Aircraft engine temperature and pressure as it applies to the bleed...
Fiberglass fabric duct installations are prevented from swelling when...
At no time shall fire extinguishing residue, such as that resulting...
One common type of variable-area orifice used on augmenters is the
The unit of a jet engine alternating current (AC) ignition system that...
Engine bleed air (EBA) check valves are installed to
The air turbine (impingement) starter used on jet engines
An H-2 emergency assembly (bailout bottle) supplies oxygen to the user...
Liquid oxygen (LOX) converts to gaseous oxygen (GOX) at an expansion...
Fuel system disconnect couplings are used
The manual control valve in the variable isobaric pressurization...
The purpose of the pneumatic relay in a cabin pressurization system is...
When two or more turbine wheels are used in a jet engine, what is...
Classified as to structure, which of the following is not a type of...
A primary function of the low-level shutoff valve is to control the...
What effect does the divergent design of a jet engine diffuser have on...
Structurally, the most common type of oil pump in use is the
The three types of shutoff valves used in the crossfeed fuel system...
The fuel subsystem designed to minimize fuel boiling is
A liquid coolant system (LCS) keeps electronic components cool by
The velocity of the stream of air that flows through a jet engine...
In a jet engine, fuel is metered for combustion by the
The fuel system component used to prevent excessive pressure from...
In a molecular sieve oxygen generating system (MSOGS), water droplets...
The output pressure and the flow ratings of a centrifugal-type fuel...
If the temperature of the bleed air from a cargo-type air conditioning...
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