What Are The Most Common Hydraulic System Applications In Aerospace?

In the fascinating world of aerospace, hydraulic systems play a crucial role in ensuring the smooth functioning and safety of various aircraft. From the towering heights of commercial airplanes to the nimble maneuverability of helicopters, these hydraulic systems find their applications in a wide range of functions. Whether it’s controlling the landing gear, operating the flight controls, or powering the brakes, hydraulics provide the necessary force and precision to keep planes and helicopters soaring through the skies. Join us as we explore the most common hydraulic system applications in aerospace, unraveling the intricate mechanisms that make flight possible.

Flight Control Systems

Primary Flight Control

The primary flight control system is responsible for crucial aspects of controlling the aircraft’s attitude and movements in the air. It consists of various components, including control surfaces such as ailerons, elevators, and rudders. These surfaces are operated by hydraulic actuators which convert hydraulic pressure into mechanical force, allowing the pilot to maneuver the aircraft. The hydraulic system ensures the smooth and precise movement of these control surfaces, enabling the pilot to maintain control over the plane’s pitch, roll, and yaw.

Secondary Flight Control

The secondary flight control system augments the primary flight control system, providing additional control options for the pilots. One common example is the spoilers, which are installed on the wings. These spoilers can be extended upwards, creating drag and reducing lift to assist with the aircraft’s descent. They also function as an additional roll control mechanism during flight. Similar to the primary flight control system, hydraulic actuators play a crucial role in operating the secondary flight control components, enabling fine-tuned maneuverability and control.

Landing Gear Systems

Extension and Retraction

The landing gear system is responsible for safely extending and retracting the landing gear during takeoff and landing. hydraulic actuators are utilized to power this process. When the landing gear lever or button is activated by the pilot, the system is engaged, and hydraulic pressure is directed to the actuators, causing them to extend or retract the landing gear. Hydraulic power ensures a reliable and swift response for the landing gear operation, allowing for seamless transitions between flight and ground operations.

Shock Absorption

Upon landing, the landing gear system relies on hydraulic power to absorb the impact and distribute the resulting forces. Hydraulic struts and shock absorbers effectively absorb and dampen the energy generated during touchdown. By utilizing hydraulic pressure and fluid displacement, these systems provide a cushioning effect, minimizing stress on the airframe and enhancing passenger comfort. This capability is especially important during challenging landing conditions or emergency situations.


The landing gear system also incorporates hydraulic steering mechanisms, which enable ground maneuverability while taxiing on runways and during other ground operations. hydraulic power is applied to actuators, allowing for controlled and precise steering of the aircraft’s nose wheel or main landing gear wheels. This steering capability ensures safe navigation on the ground, providing pilots with the ability to navigate turns, taxiways, and parking areas smoothly and efficiently.

Braking Systems


Braking systems are critical for aircraft as they facilitate safe deceleration and bring the aircraft to a stop during landing or aborted takeoff scenarios. Anti-skid technology, integrated with hydraulic systems, is employed to prevent the wheels from locking up during the braking process. By continuously modulating the hydraulic pressure distributed to the brakes, the anti-skid system allows optimal braking force while preventing wheel skidding. This technology enhances safety and control during landing, ensuring maximum grip and reducing stopping distances.

Parking Brake

The parking brake is a critical component of the braking system, utilized to keep the aircraft in a stationary position while parked or during engine start-up. It is activated by engaging a lever or engaging a mechanism in the flight deck, which directs hydraulic pressure to hold the brakes in a locked position. The hydraulic system maintains the necessary pressure to keep the brakes engaged until the parking brake is released. This feature allows the aircraft to remain stationary even on sloping surfaces or under windy conditions.

Emergency Brake

In situations that require immediate and maximum braking force, such as an aborted takeoff or an emergency landing, the emergency brake system provides a vital solution. By activating this system, hydraulic pressure is rapidly applied to the brakes, ensuring swift deceleration and enhancing passenger safety. The emergency brake system is designed to provide an additional layer of braking power when traditional braking systems may not be sufficient. It serves as a crucial backup, instilling confidence and control in critical situations.

Thrust Reverser Systems

Reverse Thrust Activation

Thrust reversers are employed to augment the braking force during landing and to assist in deceleration while conserving brake wear. Hydraulic systems play a pivotal role in the activation of thrust reversers. When the pilot initiates the reverse thrust operation, the hydraulic system directs high-pressure hydraulic fluid to actuate the thrust reverser doors, diverting the engine’s exhaust flow forward and creating a reverse thrust force. This hydraulic-assisted mechanism enhances the effectiveness of brakes during landing, providing additional stopping power and reducing runway distances required for touchdown.

Control and Regulation

In addition to the activation of thrust reversers, hydraulic systems are responsible for controlling and regulating their deployment and operation. Hydraulic actuators are utilized to precisely adjust the position and orientation of the thrust reverser doors. This allows for the effective control and modulation of the reverse thrust force, ensuring optimal performance based on the specific flight conditions. The hydraulic system’s ability to maintain consistent and precise control over the thrust reversers enhances safety during landing and provides pilots with a versatile tool to manage aircraft deceleration.

Cargo Handling Systems

Loading and Unloading

Cargo handling systems are essential for efficiently loading and unloading cargo and baggage during ground operations. Hydraulic power is harnessed to operate the various mechanisms involved in cargo handling, enabling the movement of pallets, containers, and other cargo equipment within the aircraft. hydraulic actuators and lift systems are utilized to raise or lower cargo compartments, facilitating the loading and unloading processes with ease and precision. The hydraulic system’s strength and reliability enable efficient cargo handling, minimizing ground time and maximizing operational efficiency.

Cargo Door Operation

Cargo doors are crucial components of an aircraft’s cargo system, facilitating access to cargo compartments. Hydraulic systems are employed to power the opening and closing of these doors, ensuring secure and efficient operations. By applying hydraulic pressure to the door actuators, the cargo doors can be smoothly and reliably operated, allowing for quick turnaround times. This hydraulic-assisted functionality not only improves cargo handling efficiency but also enhances safety and cargo security during the loading and unloading processes.

Flight Spoiler Systems

Lift Reduction

Flight spoiler systems serve a critical role in reducing lift during specific phases of flight, primarily during descent and landing. Hydraulic systems power the activation of spoilers, which are installed on the top surfaces of the wings. When deployed, spoilers interrupt the smooth airflow over the wings, creating turbulence and reducing lift. This lift reduction enhances the aircraft’s descent rate and aids in maintaining an optimal approach angle during landing. Hydraulic actuators ensure precise and swift deployment and retraction of the spoilers, providing pilots with enhanced control and maneuvering capabilities.

Roll Control

In addition to lift reduction, flight spoiler systems contribute to roll control during flight. By differentially activating spoilers on each wing, hydraulic actuators enable the modulation of lift on either side, allowing for effective roll control. This feature plays a crucial role in maintaining stability and maneuverability during flight, especially during banking or turning. The hydraulic system’s ability to smoothly and accurately operate the flight spoilers ensures that the aircraft remains responsive and well-controlled throughout various flight conditions.

Flap Systems

Takeoff and Landing Configuration

Flap systems are essential for configuring the aircraft’s wing surfaces during takeoff and landing. Hydraulic actuators are utilized to deploy flaps, altering the shape and lift characteristics of the wings. During takeoff, flaps are typically positioned in a downward direction to increase lift and improve low-speed performance. Conversely, during landing, the flaps are extended further to generate increased drag, enabling safer and slower approach speeds. The hydraulic system’s ability to efficiently operate the flap system provides crucial assistance in achieving optimal takeoff and landing configurations.

Drag Control

Flap systems also contribute to drag control during flight. By adjusting the position of flaps, hydraulic actuators facilitate the modulation of wing surface area and airflow characteristics, enabling precise control over the aircraft’s drag profile. Pilots can adjust the flaps based on flight requirements, allowing for comfortable cruising speeds, reduced fuel consumption, and maneuverability. The hydraulic system’s responsiveness and reliability in managing the complex movements of flaps ensure pilots have the necessary tools to optimize flight performance, ultimately contributing to safer and more efficient journeys.

Aerial Refuelling Systems

Boom Operation

Aerial refueling systems, such as the boom system, enable aircraft to receive fuel while in flight, extending their operational range and capabilities. Hydraulic systems are integral to the operation of the boom, which extends and connects to the receiving aircraft for fuel transfer. The hydraulic actuators in the boom system allow for precise control and maneuverability, ensuring successful positioning and connection with the receiving aircraft. This hydraulic-assisted process provides a reliable and efficient means of refueling, enabling increased operational flexibility and endurance for military and long-range aircraft.

Refueling Control

Hydraulic systems are also employed to control and regulate the fuel transfer during aerial refueling operations. By utilizing hydraulic pressure, valves and mechanisms in the refueling control system enable precise flow control, ensuring the accurate and safe transfer of fuel from the tanker to the receiving aircraft. The hydraulic system’s ability to maintain stable and consistent fuel flow rates enhances the efficiency and reliability of aerial refueling, reducing flight interruptions and allowing for sustained operations during extended missions.

Thrust Vector Control Systems

Rocket Engine Control

Thrust vector control systems are primarily found in high-performance aircraft and rockets, where they play a pivotal role in maneuverability and directional control. Hydraulic systems are utilized to control the nozzle of a rocket engine, allowing the pilot or autopilot to adjust the direction of thrust. By manipulating the hydraulic actuators, the pilot can direct the thrust force in different directions, enabling precise and agile movements during flight. The hydraulic system’s ability to swiftly and accurately control the thrust vectors provides the aircraft or rocket with enhanced maneuverability, improving overall performance and safety.


Thrust vector control systems significantly contribute to an aircraft’s maneuverability, especially during challenging flight conditions or combat scenarios. By manipulating the direction of thrust, hydraulic actuators enable complex movements such as pitch, roll, and yaw, offering pilots improved control and agility. This capability is particularly valuable for military aircraft engaged in air-to-air combat or evasive maneuvers. The hydraulic system’s responsiveness and precision in managing the thrust vector controls provide pilots with the necessary tools to navigate and outmaneuver potential threats effectively.

Aircraft Door Systems

Passenger/Crew Entry and Exit

Aircraft door systems are crucial for facilitating passenger and crew entry and exit before and after flights. Hydraulic systems power the opening and closing of doors, allowing for safe and efficient boarding and disembarkation. By using hydraulic pressure to activate the door mechanisms, crew members can smoothly operate the doors, ensuring passenger safety and comfort. The hydraulic system’s reliability and strength ensure that these doors can withstand the forces during flight and provide ease of access for passengers and crew members during ground operations.

Pressurization Control

Aircraft doors also play a role in pressurization control, especially in pressurized aircraft cabins. Hydraulic systems are employed to seal and secure the doors tightly during flight, effectively maintaining and regulating cabin pressure. By utilizing hydraulic pressure, the doors are pressed against the aircraft’s structure, forming an airtight seal. This ensures that the desired cabin pressure is maintained, providing a comfortable and safe environment for passengers and crew. The hydraulic system’s ability to maintain precise pressure control enhances passenger comfort and safety during flights, particularly during climbs and descents.

In conclusion, hydraulic systems have a multitude of vital applications in aerospace, ranging from flight control and landing gear systems to braking and cargo handling. These hydraulic-powered systems enable safe and efficient aircraft operations, contributing to enhanced control, maneuverability, and passenger comfort. Their reliability and responsiveness play a crucial role in ensuring the successful operation of various aircraft systems, ultimately making air travel safer and more enjoyable for all.