Aircraft Fuel Valve: 5 Interesting Facts To Know


What are the different aircraft fuel valves ?

Aircraft Fuel Valves | Gravity Feed Fuel System Aircraft

Aircraft with high wings are commonly found to have a fuel tank in each wing. The fuel is delivered by gravity owing to the placement of the tanks above the engine, hence called gravity feed fuel systems. This is the other classification of Aircraft Fuel System after Fuel Pump. Venting operation can be performed in an area located liquid-fuel existed after the de-fueling that tank , it will maintain atmospherics pressure level. Two tanks perform venting to insure coequal pressure level for both while feeding the engine jointly.

Each tank has a single screened outlet that provides lines to either a gasoline shutoff valve or a multi-position selection valve.

Aircraft fuel valves are used in a variety of ways in aircraft fuel systems. They are utilized to stop the flow of fuel or direct it to a particular place. Lighter aircraft fuel system might just have one valve, the aircraft fuel selector valve, in addition to sump and drain valves. The shutdown and selecting functions are combined into a single valve.

Different types of valves in large airplane fuel systems

There are various valves in large airplane fuel systems. The majority simply open and close and are referred to by multiple names depending on their location and purpose in the fuel system. The shutoff valve, transfer valve, and cross feed valve are some of the examples. Fuel valves can be controlled manually via a solenoid or by an electric motor.

Fuel Shut Off Valve

A shutoff valve is a valve that regulates the flow of fluid into or out of a fluid system. In a blueprint, a shutoff valve is represented by two arrows facing one other. When this sort of valve is tripped, the flow is abruptly halted, and the operator is informed by an indicator disc that the electrical circuit has been opened due to a system failure.

Fuel Shut Off Valve of Francis Turbine; Image Credits: Noodle snacksGordon Power Station Control ValveCC BY-SA 3.0

The hand lever plays a significant role in opening the valve after resolving the system fault and closing the circuit again. However, the circuit will stay open if the system failure is not addressed satisfactorily. In addition, pushing the hand lever will not open the valve since it disengages the valve stem from the handle.

Transfer Valve

The transfer valves take fuel from Tank 5 and distribute it to the wing tanks. They work in the identical way as elaborated, but with a different fuel source. Tank 5 is a fuselage-mounted auxiliary tank that consists of a rigid tank and a bladder cell. The stiff tank is in front of the bladder cell. Therefore, this tank is filled only using the pressure system.

Crossfeed Valve

In most aircraft, the fuel system has a left and right tank in the corresponding wings. Each tank typically supplies fuel to the wing’s motors. These two sides of the fuel system are connected temporarily using the crossfeed valve.

This design allows the fuel to go the shortest distance while keeping the systems separate, preventing a leak on one side from draining the entire system. For this reason, the cross feed valve is usually kept closed. Fuel flow is allowed by the cross feed valve from a tank that has too much fuel to the one that has too little. If the left fuel pump fails, the right-sided fuel pump will pump fuel from the right tank and give it to both engines one and two via the automatically opened cross feed and vice versa.

1. Aircraft with high wings are commonly found to have a fuel tank in each wing. The fuel is delivered by gravity owing to the placement of the tanks above the engine, hence called gravity feed fuel systems.

2. Aircraft fuel valves are utilized to stop the flow of fuel or direct it to a particular place. Lighter aircraft fuel system might just have the aircraft fuel selector valve, in addition to sump and drain valves. The shutdown and selecting functions are combined into a single valve.

3. The large airplane fuel systems have valves referred to by multiple names, depending on their location and purpose in the fuel system. The shutoff valve, transfer valve, and cross feed valve are some of the examples, that can be controlled manually via a solenoid or by an electric motor.

4. Aircraft Fuel Selector Valve or fuel control valve is a major type of aircraft fuel valve that receives fuel the via fuel lines. The primary role of this valve is to serve as a fuel shut off valve.

5. Further classifications like Fuel Primer Valve, Sump Valve, Strainer Valve, Drain Valves, Metering Valve, Duplex Fuel Selector Valve and Pressure Relief Fuel Valve have also been described.

*****

What is Fuel Selector Valve in aircraft?

Aircraft Fuel Selector Valve Definition

Aircraft Fuel Selector Valve or fuel control valve is a major type of aircraft fuel valve that receives fuel the via fuel lines. The primary role of this valve is to serve as a fuel shut off valve. This is essential to allow the crew to prevent fuel from reaching the engine in the event of a fire. The airplane pilot full control in which tank  will feed the engine in the second function during flying.

What is the purpose of Aircraft Fuel Selector Valve?

The aircraft fuel selector valve allows you to choose fuel from a variety of fuel tanks. LEFT, RIGHT, BOTH, and OFF are the four positions of a typical selector valve. The reason for having only LEFT and RIGHT alternatives is to allow pilots to balance their fuel loads to minimize the banking moment.

Fuel comes from the respect tank that accounts for the LEFT or RIGHT position. However, when aircraft fuel selector valve makes selection for BOTH parts, aircraft fuel will come from both tanks. To maintain the quantity of fuel remaining in each wingtank, utilize the LEFT or RIGHT orientation, though some Cessna planes only operate fuel from both tanks.

How do different fuel selector valves work? | What are the remotely operated Aircraft Fuel Valves ?

Manual Fuel Selector Valve

In aviation fuel systems, there are three primary types of hand-operated fuel selector valves. Fuel selection valves such as the cone-type and the poppet-type are extensively utilized in lighter aircrafts. On transport category airplanes, gate valves are utilized as shutdown valves. While many are motorized, hand-operated gate valves are used in a variety of applications.

Cone Valve

A conetype valve typically comprises of individual machined valve housing and a rotational brass-made or nylon made cone, known as a plugvalve. The pilot uses a connected handle to manually rotate the cone. Fuel can flow from the designated source to the engine through passageways cut into the cone as it rotates. This happens when the passage coincides with the housing’s machined fuel input port. The cone can also be turned so that the passageway will not be able to linedup with any fuel I/P ports, this is the valve’s fuel OFF position.

aircraft fuel valve
Cone Valve

Poppet Valves

Poppet valves are also often used in selector valves, as the handle is spun in this valve, a cam on the connecting shaft will lift the poppet from the seat of the corresponding port and the ports that aren’t picked at the same time are closed off by spring-assisted poppet. The Detent lock the valve into place when rise of the poppet from its seat due to the cam occurs. The valve is in the OFF position a positive detent is not accompanied by any engagement between the cam and any of the poppets, and there is a positive detent. Some selector valves employ a similar mechanism, except instead of poppets, they use balls.

Gate Valves

In complex fuel system of transportation categories aircraft, a single selector valve is not employed. Instead, a series of ON/OFF, or cutoff, type valves are plumbed between system components to control fuel flow. Hand-operated gate valves, such as fire control valves, can also be used because they do not depend on electricity to turn off the fuel flow upon pulling the emergency fire handle.

Gate Valve; Image Credits: Heather Smith, Cryogenic-gate-valve-The-Alloy-Valve-StockistCC BY 3.0

These valves are generally installed in each engine’s fuel feed line. Ground-operated de-fueling valves and booster pump isolation valves are gate valves those are operated in manual mode to shutting off the fuel supply to the booster pump’s I/P. It allows easy replacement of the booster pump without emptying the tank. A sealed gate or blade slides into the fuel line when a gate valve is closed and interrupts the flow. if the handle is rotate, the actuator arm inside the valve will move down the gate blade to seal fuel’s flow path. A thermal relief by-pass valve is integrated to decrease pressure build up against the closed gate due to the rise in temperature.

Electric Motor Operated Aircraft Fuel Valve

Due to the remote location of fuel system components from the cockpit, electric motors are commonly used to operate fuel system valves on large aircraft. These valves are electrically actuated towards functioning the same as the manually controlled valves.

The gate valve and the plug-type valve are the two most prevalent aircraft fuel valves that operated by an electric motor. The motor-operated gate valve will turn the actuating arm of the valve, thereby displacing the fuel gate in/out of the fueling path, with automatic gear mechanism and gate/blade is sealed, just like the manually controlled gatevalve.

A manual over ride lever may give facility to the technician to check the valve’s orientation and manual control. The usage of a motorized plug-type fuel valve is less prevalent; instead of rotating the plug or drum manually, an electric motor rotates it. Large aviation fuel system valves allow or stop fuel flow, depending on the type of valve employed.

Solenoid Operated Aircraft Fuel Valve

Electric solenoids are another option for controlling a fuel valve that is positioned far away. When an opening solenoid is energized, it creates a magnetic pull that opens a poppet-type valve and to lock the valve in the open position, a spring drives a locking stem into a notch in the stem of the poppet. Fuel is then pumped via the hole left by the poppet.

A closing solenoid is energized to close the poppet and stop fuel flow. The magnetic power force of the solenoid’s will overcome the tension of the locking stem spring and pushes the lockingstem out of the notch of the poppetstem. The poppet is pushed back into its seat by a spring hidden behind it. Solenoid-operated fuel valves have the advantage of opening and closing quickly.

A means of positively identifying the valve’s location at all times is a feature of all aviation fuel valves. Manually operated valve achieve this by utilizing detent situated by a spring-loaded pin or analogous protrusion when the valve is adjusted in each position. With the accompaniment of a labelling and directing handle, it’s easy to know if the valve is in the proper position by vision and intuition.

In addition to the switch position, position annunciator lights are used on motor and solenoid-operated valves to show valve position and location of the fuel valve is displayed in diagrams called upon the flat-screen displays on the flight management system (FMS) fuel pages. An outside position handle or lever indicates the position of many valves. When the maintenance staff is close to the valve, the technician can manually position it with this same lever.

Other Aircraft Fuel Valves

Aircraft Fuel System Check Valve | Aircraft Fuel Tank Flapper Valves

A check valve enables unidirectional draining of fuel back into the main tanks, fuel swing check valve, also known as the swing flapper check valve, is used to prevent fuel from flowing back from the ejector pumps to the engine feed subsystem. It features two ports, one for the media inlet and the other for the media output. A pressure differential is required for a check valve to function. Therefore, to open the valve, they need more pressure on the I/P side than O/P side.

Aircraft Duplex Fuel Selector Valve

Duplex Fuel Selector valves are valves with two chambers that allow two separate fuel lines to be switched simultaneously. As a result, they’re suitable for fuel-injected engines that require a return line. In addition, these valves have the advantage of allowing fuel to be returned to the same tank from which it was drawn, eliminating the need to discharge fuel overboard.

Duplex Valve; Image Credits: Heather Smith, Duplex-ball-valves-The-Alloy-Valve-StockistCC BY 3.0

Aircraft Fuel Primer Valve

Before starting the engine, the fuel primer is the aircraft fuel valve that is utilized to fuel the tank and vaporize them directly into the cylinder. When it’s chilly outside, and machines are hard to start, the gasoline primer comes in handy since the heat available is not enough to evaporate the fuel in the carburetor. When you’re not using the primer, make sure it’s locked in place. If the knob is allowed to move during flight, it may vibrate out of place, resulting in an abnormally rich fuel-air mixture.

Aircraft Fuel Sump Valve

The fuel flows through a filter after leaving the fuel tank before entering the carburetor to remove any moisture and other particles. These pollutant will settle in a reservoir at the under-surface of the strainer assembly because these are hefty and applicable in a fuel system and/or gasoline tank, a sump is a low location.

Aircraft Fuel Strainer Valve

Before each flight, the fuel strainer valve is the aircraft fuel valve that is drained, and fuel samples should be depleted and visually inspected for impurities and water.

Aircraft Fuel Drain Valves

Presence of water in the sump might be very risky because it can freeze and clogged fuel line during winter or cool environments. In addition, it can pour into the carburetor and shut off the engine in hot conditions. If the sump contains water, there is likely to be more water in the fuel tanks, which should be drained until there is no trace of moisture. The aircraft should not take off until the engine fuel system has been cleared of all water and impurities.

Aircraft Fuel Metering Valve

At all speeds and altitudes where the engine may be operated, the aircraft fuel valve in the fuel metering system must meter fuel proportionately to air to provide the engine’s optimum fuel/air mixture ratio. The fuel from the carburetor must be atomized and distributed into the bulk airflow. This must be done for the fuel/air charges to all cylinders to contain the same amount of fuel. Therefore, each cylinder in the engine should receive the same fuel/air mixture and fuel/air ratio.

Aircraft Fuel Tank Pressure Relief Valve

A relief valve is a valve in a pressurized system used to adjust pressure for the system’s optimal performance. Relief valves are meant to prevent system failures and protect equipment from over-pressurized conditions in your business. Relief valve are usually responsible for regulation of pressure level in fluid/compressed air-system.

The opening of these valves is proportional to the rise in system’s pressure and therefore, if the system is somewhat over-pressured, they will not fly all the way open. Instead, they gradually open in slow process, allowing the system to restore to its original pressure setting. The valve closes once that level is approached.

This article is a part of the ongoing series about the Aircraft Fuel System.

Esha Chakraborty

I have a background in Aerospace Engineering, currently working towards the application of Robotics in the Defense and the Space Science Industry. I am a continuous learner and my passion for creative arts keeps me inclined towards designing novel engineering concepts. With robots substituting almost all human actions in the future, I like to bring to my readers the foundational aspects of the subject in an easy yet informative manner. I also like to keep updated with the advancements in the aerospace industry simultaneously. Connect with me with LinkedIn - http://linkedin.com/in/eshachakraborty93

Recent Posts