You know that safety won’t be compromised during aircraft manufacturing. To ensure aircraft safety during take-off, landing, etc., the manufactures use better technologies and advanced safety precautions. You can find applications of hydraulics in aircraft, which indicates how safe a hydraulic system is. All airliners, military aircraft and helicopters use hydraulics applications because of its cost efficiency, ease of maintenance and operation efficiency. Hydraulic applications of smaller aircraft are limited to wheel brakes only. Whereas, complex aircraft uses hydraulics for controlling various components.
More details on aircraft hydraulic system are discussed below.
The hydraulic system is an integral part of every aircraft because of its reliability, dependability, speed, and power density. And most importantly, powerful and sudden response for an immediate input can be achieved only using hydraulics other than electric and pneumatic transmission systems. Also, the small and lightweight design of hydraulic systems will improve the efficiency and reduces emissions.
Gun turrets, autopilot, shock absorption system, landing gears, wing flaps, doors and hatchways, brakes, bomb bay doors, etc.. are some hydraulic applications in an aircraft. The principle behind all these device operations is Pascal’s law. Let’s discuss the basics of some of these aircraft hydraulic system applications.
Also, Read: Examples of Hydraulic system
Gun turrets in military aircraft are weapon mount that lets the weapons to be aimed and fired. To operate a gun turret, a hydraulic motor is attached with the turrent ring with gears. When the high-pressure fluid passes through the pump, the turrent will move. Hydraulics helps the gun turrets to change direction instantaneously.
The flight control system that helps the pilot to fly without continuous hands-on control by sending signals regarding the required mode is called autopilot system. In aircraft, servos are the device that operates the control surfaces. A small electrically controlled hydraulic actuator is located in hydraulic servos. The valves present inside the actuator will pass fluid in and out of the cylinder with connected pistons. These pistons are connected with the control surfaces that perform the required operations.
Shock Absorption System in Landing Gears
For safe landing, reducing the magnitude of vibrations are important. This shock absorption system in aircraft contains two separate chambers containing nitrogen gas and hydraulic fluid, to absorb and dissipate shock loads on landing. The first chamber containing compressed gases will act as a spring to absorb the shocks and the second with aircraft hydraulic fluid will reduce this effect by forcing hydraulic fluid through orifices.
The aircraft hydraulic system assists the wing flaps to lower and raise. Generally, this system consists of a selector valve(4-way poppet-type valve) and an actuating cylinder. The poppet valve act in pairs to push fluid into one side of the cylinder and to release it through the other opening towards the reservoir.
The wheel brakes are used to slow down the aircraft during landing roll on the runway. The aircraft wheel brake system is attached with the rudder pedal and is operated by hydraulic pressure. The force applied on the rudder pedal will push fluid through the connecting line towards the wheels to stop/slow down the aircraft.
The important properties of aircraft hydraulic fluid to be considered while selection includes low freezing point, minimum viscosity, corrosion & oxidation stability, anti-foam properties, fire resistance, temperature stability, etc.. Aircraft hydraulic system uses different types of hydraulic fluids in aircraft based on the properties of hydraulic fluid, These types are classified into mineral oils, chlorophenyl silicone oil, synthetic hydrocarbon, water/glycol, and phosphate ester.
Any aircraft hydraulic system failure can result in the loss of control and damage the aircraft. So, proper aircraft hydraulic system maintenance is important to ensure the safety of the aircraft.