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Facts You Should Know About Aviation Hydraulics and Landing Gear

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March 25, 2021

Facts You Should Know About Aviation Hydraulics and Landing Gear

If you are considering training in the field of aviation, you have undoubtedly heard terms such as hydraulics and landing gear. Nevertheless, your knowledge of these concepts may not go too far beyond that. Unless you have been researching these topics extensively, you most likely only know that each of these concepts is important in terms of a plane's overall functionality. However, if you are going to get into the field by training in aviation mechanics or flight, understanding how both hydraulics and landing gear work is imperative. With that in mind, the following is an in-depth look at each. 

 

What are Aviation Hydraulics? 

 

For those who are unfamiliar, aviation hydraulics systems are one of the systems that help planes take off, fly, and land. Although two different systems can be installed to help control these functions: pneumatic or hydraulic, aviation hydraulic systems are far more popular because they provide planes and pilots with the most reliable system available. 

 

In particular, aviation hydraulic systems are used to help control and manage equipment such as brakes, flaps, thrust reversers, flight controls, and of course, landing gear. Hydraulic systems are the preferred system because they offer the perfect amount of pressure to operate these systems. This makes them an ideal fit for airplanes of all kinds. 

 

Generally speaking, hydraulic systems are said to work better because they typically use non-compressible liquids. This means they cause no delay in movement, unlike pneumatic systems. This is obviously a great thing when dealing with something as serious and sensitive as flying. 

 

Basic Components 

 

When it comes to the basic components of a hydraulics system, they are as follows: 

  • Pump: The pump generates the power that helps to pressurize the system. 
  • Reservoir: The reservoir is a vessel used to store the fluids used within the hydraulic system. 
  • Actuating Cylinder: The actuating cylinder is one of the most important parts of the hydraulics system. It is where the work of the system is performed, by converting fluid pressure and flow to mechanical force. 
  • Pressure Relief Valve: The pressure relief valve is used to protect the system from being over-pressurized. 
  • Flow Control Devices: These are items such as check valves and selector valves. These devices direct the flow of fluids throughout the system and allow fluids to flow in and out of the actuating cylinder.  
  • Heat Exchanger: The heat exchanger helps maintain the hydraulic fluid at the proper operating temperature. 

 

Types of Hydraulic Fluid 

 

Hydraulic fluid helps to maintain the functionality of hydraulic systems. The three main types of fluids being used in most hydraulics systems today are: 

  • Mineral Based Fluids: This type of oil is dyed red and is a kerosene petrochemical product. It works great for lubrication and prevents foaming and corrosion. It is also very stable and works well regardless of temperature changes. This is considered the most compatible oil for smaller planes in terms of aviation hydraulics. 
  • Vegetable Based Fluids: Vegetable oil is dyed blue and is most often made of castor oil. While this oil is pretty effective, it is also known to cause some sludge and corrosion. For this reason, it is typically only used in older aircraft and is being phases out of use. 
  • Synthetic Based Fluids: This type of oil is usually dyed purple and is typically composed of a man-made phosphate ester, an ester derived from an alcohol and phosphoric acid. However, it can also be colored either green or amber. Despite its benefits, it can ruin paints, soften some plastics, and sometimes slowly chip away at the insulation, which can degrade the wiring over time. This type of fluid is common on larger transport aircraft. 

 

Advantages of Using Aviation Hydraulics 

 

Now that you know more about what aviation hydraulics are and how they work, let's take a look at the benefits of using aviation hydraulics. They are: 

  • Cost-Effectiveness: One of the top benefits of using aviation hydraulics is that they are relatively cost-effective to install and maintain. Hydraulics are also energy efficient because they run continuously at a constant speed to generate the power required to operate. 
  • Reliability: Another of the top benefits of using hydraulic systems is that they are very dependable and reliable. This is because the underlying mechanics are so simple to understand and maintain, making them easy to use and repair as needed. Also, the amount of moving parts are minimal, which makes it more resistant to potential failures. 
  • Quick and Efficient Response: Additionally, hydraulics systems provide a quick and efficient response to control inputs. This is imperative to aviation because responding quicker and more efficiently can be critical to having a safe flight. This is especially the case when flight conditions are risky due to unsavory weather. These are the times in which pilots need to use a variety of controls without worrying about how long it will take for the functions to actually work. 
  • Non-Compression: Another benefit of aviation hydraulic systems is that the fluid is not susceptible to compression, as mentioned before. This is important because there are profound pressure changes in the flight and landing of airplanes. 

 

Hydraulics and Landing Gear 

 

As mentioned, hydraulic systems also play a major role in a plane's ability to use landing gear. In particular, they help to control landing gear retraction systems. With the help of pressurized hydraulic fluid, which serves to actuate the linkages tasked with raising and lowering the landing gear, the hydraulics system is essential to a plane's ability to take off and land. 

 

How it Works 

 

On smaller planes, the landing gear consists of three wheels: two main wheels, as well as one positioned in either the front or the rear. On larger planes, the landing gear typically consists of two main landing gear with either two or four wheels. The number of wheels is dependent on the size of the aircraft and a nose gear with either one or two wheels.   

 

When the landing gear switch is moved into the 'up' position, the hydraulic fluid is sent to the 'gear up' line, which then triggers the landing gear to go up. When this is done, the fluid is sent through sequenced valves and down to the gear actuating cylinders. On the other hand, when it's time to extend the landing gear, the process works in a similar fashion. The engine or electricity can power the pumps pressuring the fluid in the system. 

 

Other Uses for Hydraulics in Aviation 

 

In addition to helping control the landing gear, there are plenty of other applications for hydraulics in aviation. For instance: 

  • Smaller Planes: On smaller planes, hydraulics are used to operate brakes. 
  • Larger Planes: On larger planes, hydraulics systems are used for things such as controlling the wing flaps, flight control surfaces, spoilers, and several other systems. 

 

Interested in Aviation? 

 

If you are interested in learning more about aviation or pursuing training for a career in aviation, attending Spartan College of Aeronautics & Technology is an excellent option. Those who attend Spartan College join the ranks of over 100,000 pilots and technicians trained there thus far. Rather than leaving it to chance, attending Spartan College will allow you to access the expertise of an institution that has been training many people in the aviation field for nearly a century. Ready to get started? Contact us today for more information, such as how to apply and how to get financial assistance (for those who qualify). 

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