Vital Role of Hydraulic System in Aircraft

In the field of aviation, hydraulics and their related systems play a vital role in the functionality of aircraft. In fact, aviation hydraulic systems are responsible for helping planes take off, fly, and land. While there are two different systems that help control these functions, those of which are pneumatic or hydraulic, hydraulic systems are more popular because they are increasingly reliable.

Specifically, aviation hydraulic systems are utilized to help control and manage various aircraft equipment like brakes, flaps, thrust reversers, flight controls, and landing gear. Hydraulic systems offer the perfect amount of pressure to operate these systems, making them ideal for a wide range of aircraft models. The reason they work better is because they take advantage of non-compressible liquids, meaning that they cause no delay in movement, unlike pneumatic systems.

Basic Components of Hydraulic Systems

Hydraulic systems are made up of six key components: a pump, reservoir, actuating cylinder, pressure relief valve, flow control devices, and heat exchanger.

  • Pump: The pump produces the power that helps pressurize the system.
  • Reservoir: The reservoir is a vessel utilized to store the fluids used in the hydraulic system.
  • Actuating Cylinder: The actuating cylinder is where fluid pressure and flow is converted into mechanical force.
  • Pressure Relief Valve: The pressure relief valve is utilized to protect the system from being over-pressurized.
  • Flow Control Devices: These devices consist of check valves and selector valves, each of which direct the flow of fluids throughout the system, enabling fluids to flow in and out of the actuating cylinder.
  • Heat Exchanger: The heat exchanger helps maintain the hydraulic fluid at the right operating temperature.

Types of Hydraulic Fluid

There are three main types of fluids being used in hydraulic systems today.

  • Mineral Based Fluids: A mineral based fluid is typically a kerosene petrochemical product that is dyed red. Mineral based fluids offer ample lubrication, prevent foaming and corrosion, and work well regardless of temperature fluctuations. In terms of aviation hydraulics, they are considered great choices for smaller jets.
  • Vegetable Based Fluids: Vegetable oil is often made of castor oil and is dyed blue. While it is effective, it is known for causing some sludge and corrosion. As such, it is only used in older aircraft but will soon become obsolete.
  • Synthetic Based Fluids: A synthetic based fluid is normally dyed purple, but in some cases, may be colored green or amber. Generally, it is composed of a man-made phosphate ester derived from an alcohol and phosphoric acid. Despite the benefits it offers, it often ruins paints, softens some plastics, chips away at insulation, and can degrade wiring over time. For these reasons, it is only found on large transport aircraft.

Advantages of Aviation Hydraulics

Hydraulics offer aircraft a myriad of advantages, some of which we will outline. To begin, they are cost-effective to install and maintain. Moreover, they are energy efficient due to the fact they can run continuously at a constant speed to produce the necessary power to operate. With this in mind, they are very dependable and reliable. As they have very little moving parts, they are more resistant to potential failures. Furthermore, they provide quick and efficient response to control inputs which is critical to having a safe flight. Lastly, since they utilize non-compressible fluids, they can withstand the variable pressures experienced during flight.

How Hydraulics and Landing Gear Work

Hydraulic systems play a critical role in an aircraft’s ability to utilize landing gear. With the help of the pressurized hydraulic fluid, the landing gear linkages can be actuated, so that they can be raised and lowered.


ASAP Buying is a leading supplier of aviation hydraulics and their related components including thrust reversers, flight controls, spoilers, and more. Kickoff the purchasing process with a competitive quote on any desired item(s) and see how ASAP Buying can serve as your strategic sourcing partner. For additional questions, call or email us at any time; we are available 24/7x365!


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