Volume 2 Unit Review Exercises Aircraft Fuel System

An O-ring is a type of seal that is commonly used between the disc and valve body on a disc-type valve. O-rings are made of rubber or elastomer material and are designed to create a tight and reliable seal between two mating surfaces. They are easy to install and provide excellent sealing properties, preventing any leakage or loss of fluid or gas. O-rings are widely used in various industries due to their versatility, durability, and cost-effectiveness.

After ground refueling, approximately 3 percent of the air space is left at the top of the tanks of a cargo aircraft.

Fuel must be routed through the crossfeed manifold in order to feed any engine from any main tank on a tanker aircraft. The crossfeed manifold allows fuel to be transferred between the main tanks and ensures that fuel is available to all engines regardless of the tank from which it is being drawn. This system provides flexibility and redundancy in fuel supply, allowing for efficient operation of the aircraft.

The correct answer is that the landing gear must be in the airborne position. This safety feature ensures that fuel cannot be accidentally dumped while the aircraft is on the ground. By requiring the landing gear to be in the airborne position, it prevents any unintended activation of the fuel dump system during ground operations. This helps to prevent any potential hazards or accidents that could occur if fuel were to be dumped while the aircraft is on the ground.

To troubleshoot a fighter engine feed system component suspected of leaking, the best method is to pressurize the manifold with fuel and look for leaks. This method allows for a direct examination of the component under operating conditions, ensuring that any leaks can be easily identified. By pressurizing the manifold with fuel, any leaks will be visible and can be promptly addressed. This method is more effective than simply operating the component or pressurizing with air, as it specifically targets the fuel system and allows for a thorough inspection.

Float switches are the most likely device to be used to control the automatic pump shutoff when all fuel is depleted from a fuel tank. Float switches are designed to detect the level of a liquid, such as fuel, in a tank. When the fuel level drops to a certain point, the float switch will activate and send a signal to shut off the pump, preventing it from running dry. This helps to protect the pump from damage and ensures that fuel is not wasted. Toggle switches, pressure switches, and float valves are not specifically designed for this purpose, making float switches the correct answer.

The correct answer is that the fuel-level control valves automatically stop the flow of fuel into a tank prior to overflow. This means that the valves have a safety mechanism in place to prevent the tanks from overflowing during refueling.

The arrow stamped on the body of a check valve indicates the direction of fuel flow. This is important because check valves are designed to allow fluid to flow in only one direction, preventing backflow. The arrow serves as a visual indicator for the correct orientation of the valve to ensure proper fuel flow.

The correct answer is "Requires special tools to install." This means that one disadvantage of the quick change electrically drive fuel pump is that it requires special tools to install. This implies that the installation process may be more complicated and require additional resources or expertise. The other options listed are advantages of the quick change electrically drive fuel pump, such as not being able to install the wrong pump, shortening the time required for pump changes, and not requiring physically entering or completely defueling the tank.

Thermal relief valves are designed to prevent excessive pressure from building up in trapped lines or within the body of a sliding gate valve. These valves are specifically designed to open and release pressure when the temperature of the fluid exceeds a certain threshold, preventing damage or failure of the equipment. This feature is important in maintaining the integrity and safety of the system.

A cannon plug is a component that is designed to provide a quick and easy way to connect and disconnect wires. It is commonly used in electrical systems to simplify the installation of various components, such as a shutoff valve. By using a cannon plug, the wires can be easily connected or disconnected without the need for complex wiring or soldering, making the installation process much simpler and more efficient.

The individual tank vent manifolds on a cargo aircraft terminate in the vent box. This means that the vent system of the aircraft is designed in such a way that the individual tank vents lead to a common vent box. The vent box serves as a central point where the air pressure inside the tanks is equalized and excess pressure is released. This configuration allows for efficient venting of the tanks and helps maintain proper pressure levels during flight.

The letter "A" in the fault code indicates that a fault isolation diagram is provided. This diagram helps in identifying the specific system or subsystem that is faulty. By referring to the fault isolation diagram, the technician can narrow down the problem and focus on troubleshooting the identified system or subsystem.

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The correct answer is that the external centerline tank will transfer first. This means that when fuel is being transferred from the external tanks of a fighter aircraft, the centerline tank will be the first one to empty its contents. This is likely because the centerline tank is positioned in the middle of the aircraft, making it more accessible for fuel transfer. Additionally, transferring fuel from the centerline tank first helps to maintain the balance and stability of the aircraft during flight.

To perform an operational check of the tank scavenge system on a cargo aircraft, it is necessary to ensure that the fuel quantity in the outboard main tank is at least 12,000 pounds. This specific amount of fuel is required to properly test the system and ensure its functionality.

The jettison mast is a part of the fuel transfer system in a cargo aircraft. Its purpose is to allow for the rapid jettisoning or dumping of fuel in case of an emergency. To prevent any foreign objects from entering the fuel transfer system during this process, the jettison mast is equipped with a flame arrestor screen. This screen acts as a barrier, preventing any debris or foreign objects from entering the system and potentially causing damage or contamination.

Hydromechanical principle is used to operate fuel-level control valves. This principle involves the use of mechanical devices that are operated by hydraulic pressure to control the fuel level. It combines the principles of both hydraulics and mechanics to regulate the flow of fuel and maintain the desired fuel level in the system. This method is commonly used in various fuel control systems to ensure proper fuel supply and prevent any fuel-related issues.

A sliding gate shutoff valve is not designed to withstand extreme pressures. This type of valve operates by sliding a gate across the flow path to control the flow of fluid. However, the sliding gate design may not be able to handle high pressures effectively, as it may cause the gate to become stuck or damaged. In contrast, disc, butterfly, and rotary plug valves are better suited for handling extreme pressures due to their different designs and mechanisms.

The flapper on a flapper-type check valve is opened by gravity flow or pump pressure. This means that when there is sufficient flow or pressure from either gravity or a pump, the flapper will be forced open, allowing fluid to pass through the valve. The other options, such as spring pressure, hydromechanical action, or an electrical impulse, are not correct because they do not describe the mechanism by which the flapper is opened in a flapper-type check valve.

An inlet screen prevents foreign objects from holding the bypass valve open in a dual-impeller pump. This screen acts as a filter, allowing only clean fluid to enter the pump and preventing any debris or foreign objects from entering and interfering with the operation of the bypass valve.

When the FWD fuel system on the fighter aircraft is refueled, the FWD reservoir tank will fill first. This means that the fuel will be stored in the FWD reservoir tank before being distributed to other tanks such as the left wing, right wing, and other parts of the aircraft.

The pilot valve is the part of a piston-type fuel-level control valve that prevents fuel from entering the tank. It is responsible for regulating the flow of fuel and ensuring that the correct amount is delivered to the engine. The pilot valve acts as a gatekeeper, opening and closing to control the fuel flow based on the demands of the engine. By effectively managing the fuel supply, the pilot valve helps maintain the proper fuel level in the tank and prevents any excess fuel from entering.

In a cargo aircraft refuel system, the single point receptacle is opened by engaging the lever on the refueling nozzle. This action allows fuel pressure to flow into the receptacle. Once refueling is complete, the lever is released, and the receptacle is closed by spring tension. The spring tension ensures that the receptacle remains securely closed, preventing any fuel leakage.

To allow fuel to flow from a cargo aircraft single point receptacle to the main wing manifold during ground refueling, the refuel isolation valve must be open. This valve is responsible for allowing fuel to pass through from the single point receptacle to the main wing manifold, which then distributes the fuel to the aircraft's fuel tanks. If the refuel isolation valve is closed, fuel will not be able to flow through, preventing the refueling process. Therefore, it is necessary for the refuel isolation valve to be open in order for fuel to be successfully transferred during ground refueling.

Fuel valves control the flow of fuel through different systems in an aircraft. In this case, the question specifically asks about the fuel valves that control the flow of fuel through the jettison system. The jettison system is used to quickly and safely remove excess fuel from the aircraft in emergency situations or to reduce weight for landing. Therefore, the correct answer is "Dump," as dump valves are specifically designed to control the flow of fuel through the jettison system.

A resistor can be considered both a protective device and a load device in an electrical circuit. As a protective device, a resistor is often used to limit current flow and prevent damage to other components. It can act as a current limiter or a voltage divider to protect sensitive components from excessive current or voltage. As a load device, a resistor consumes electrical energy and converts it into heat or light. It is commonly used in circuits to control current flow, adjust signal levels, or provide a load for testing purposes.

The correct answer is the CITS control and display panel in the aft crew station. This is because the fault isolation diagram specifically requests the entry of a PMC, and the CITS control and display panel in the aft crew station is the designated location for entering this code. The other options, such as the CITS control and display panel on the windshield center post and the system status panel on the windshield center post, are not mentioned in the question as the appropriate location for entering the PMC code.

The correct answer is "hydromechanically and controlled by a solenoid." This means that the fuel level control valve on a cargo aircraft is operated using a combination of hydraulic and mechanical mechanisms, and its control is regulated by a solenoid.

The scavenge pumps on a fighter aircraft are ejector-type pumps. They are located in the F-2 tank.

To troubleshoot a boost pump problem on a fighter aircraft, the first step is to check for a direct pressure reading of the pump. This is important because it allows you to determine if the pump is functioning properly and providing the necessary pressure. By checking the pressure directly, you can identify any issues with the pump that may be causing the problem. This step is crucial in the troubleshooting process as it helps to narrow down the possible causes of the boost pump problem.

After a defuel operation, the fuel is drained from the main wing manifold of a cargo aircraft through gravity flow. This means that the fuel is allowed to flow out of the manifold due to the force of gravity, without the need for any external pumps or valves. Gravity flow is a simple and efficient method for draining fuel from the manifold, as it does not require any additional equipment or power sources.

Excessive air pressure in the fuel tanks of a cargo aircraft can be released through a vent system. A vent system is designed to allow the release of excess pressure to prevent any damage or explosion in the tanks. This system ensures that the pressure inside the tanks remains within safe limits by providing a pathway for the air to escape. A vacuum relief valve, hot air check valve, and float valve are not specifically designed for releasing excessive air pressure from fuel tanks, making them incorrect choices.

The cargo aircraft component that is designed to sense fuel pressure and transmit a signal to an indicator on the fuel management panel to allow you to determine the output pressure of a boost pump is the transmitter. The transmitter is responsible for converting the fuel pressure into an electrical signal that can be interpreted by the indicator. This allows the pilot or operator to monitor the fuel pressure and ensure that it is within the desired range for proper operation of the boost pump.

The blue READY/NWS light on a bomber aircraft aerial refueling system lets the pilot know if all conditions are satisfied prior to boom and receptacle connection.

The thermally-actuated valve in the heat exchanger outlet on a fighter aircraft fuel system is designed to prevent the fuel from exceeding a certain temperature. In this case, the correct answer is 200ºF. This means that the valve will close and restrict the flow of fuel if the temperature reaches or exceeds 200ºF, ensuring that the fuel does not become too hot and potentially cause damage or malfunction to the aircraft.

When the fuel level sensor in a fighter aircraft is uncovered, it will result in the illumination of a FUEL LOW light on the caution light panel. This sensor is responsible for measuring the amount of fuel remaining in the aircraft's fuel tank. When the sensor detects that the fuel level has dropped below a certain threshold, it triggers the FUEL LOW light to alert the pilot of the low fuel situation.

The output pressure and flow ratings of a centrifugal pump being greater than the system needs would ensure that there is enough fuel supply in case of a single pump failure. This means that even if one pump fails, the remaining pump(s) would still be able to provide an ample supply of fuel to the system, preventing any disruption in fuel flow and ensuring the continuous operation of the engines.

A malfunctioning boost pump is the most probable cause of the malfunction because a boost pump is responsible for providing the necessary pressure to route fuel to the crossfeed manifold. If the boost pump is not functioning properly, there will be no pressure available to route the fuel, leading to the observed malfunction.

The correct answer is the Ballast tank isolation valve only. This means that in addition to the dump valve, only the Ballast tank isolation valve needs to be open in order to allow fuel into the wing transfer lines to be dumped overboard. The other options, such as the Forward weapons bay vent disconnect valve and the Main pressure actuated vent valve, are not necessary for this process.

To determine if the auxiliary tank is empty while transferring fuel on a cargo aircraft, you would observe the fuel quantity indicator. This is because the fuel quantity indicator provides a visual display of the amount of fuel remaining in the tank. By monitoring the fuel quantity indicator, you can determine if the tank is empty or if there is still fuel present.

Placing the pilot trigger switch to the first detent will reset the UARRSI (Universal Air Refueling Receptacle Slipway Installation) and signal amplifier, causing the READY/NWS (Ready/Nozzle) light to illuminate. This action indicates that the manual disconnect has been reset and the aircraft is ready for aerial refueling operations again. Cycling the slipway door closed and open, pressing the aerial refueling RESET button, and placing the MODE switch to the NORM position do not specifically address the resetting of the UARRSI and signal amplifier.

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When the boom travel limits are exceeded during aerial refueling on a bomber aircraft, it will result in an automatic disconnect of the boom and receptacle. This is because exceeding the boom travel limits can cause damage to the boom or the receptacle, posing a safety risk. Therefore, the system is designed to automatically disconnect in order to prevent any potential damage or accidents.

In aircraft electrical circuits, two types of protective devices used are fuses and circuit breakers. Fuses are designed to break the circuit when excessive current flows through it, protecting the circuit from damage. Circuit breakers, on the other hand, perform a similar function but can be manually reset after tripping. Both devices are crucial in preventing electrical overloads and short circuits, ensuring the safety and reliability of the aircraft's electrical system.

During negative gravity conditions, a dual-impeller centrifugal pump is used for fuel supply. This type of pump is specifically designed to operate in low-pressure and low-gravity environments. The dual-impeller design allows for increased efficiency and improved performance, ensuring that fuel is effectively pumped even in these challenging conditions.

The correct answer is "Manually operated fuel shutoff valve." This valve is installed between the refuel manifold and each external tank on a fighter aircraft to allow selective refueling of the externals. It is manually operated, meaning that it can be controlled by the pilot or ground crew to open or close the fuel flow to the external tanks as needed.

When the PRESS LOW light extinguishes, it indicates that the boost pump on the cargo aircraft is putting out sufficient pressure. This means that the pressure indicator reading of 20 psi is considered adequate for the boost pump to maintain proper pressure levels. When the PRESS LOW light is illuminated, it suggests that the boost pump is not providing enough pressure, which is not the case in this scenario.

The letters "OL" appearing on the digital display of the multimeter indicate that the circuit voltage is higher than the highest range selected. This means that the voltage being measured is beyond the capability of the selected range, and the multimeter is unable to provide an accurate measurement.

The correct answer is surge boxes. Surge boxes are components that work together with ejector pumps to ensure that the boost pump inlet remains submerged with fuel at all times. This is important for the proper functioning of the cargo aircraft's fuel system. Check valves, float valves, and vent boxes are not specifically mentioned in relation to keeping the boost pump inlet submerged with fuel.