Hydraulic fluid is used in aircraft engines to operate various components such as brakes, landing gear, and steering systems.
The color of the fluid varies depending on the type of aircraft. There are two types of hydraulic fluids: oil-based and synthetic.
Oil-based hydraulic fluid has a different appearance to synthetic hydraulic fluid.
Let’s find out more about the different kinds of aviation hydraulic fluid and the difference in colors!
What Is Hydraulic Fluid?
Hydraulic fluid is a liquid that can be forced through pipes or hoses by applying pressure.
It is used for many purposes including powering airplane engines, operating car brakes, and moving machinery.
In an airplane engine, it powers the propeller, which turns the plane forward.
When you apply pressure to the brake pedal, it moves the brake pads into contact with the wheel rims, slowing down your vehicle.
If there is no hydraulic fluid available, these functions cannot take place.
Oil-Based Vs Synthetic Hydraulic Fluids
Oil-based hydraulic fluid has been around since the early 1900s. They were originally made from petroleum products like kerosene and diesel fuel.
Today, they’re mostly manufactured using vegetable oils and natural gas. These fluids have a specific gravity between 0.85 and 1.05.
This means that when placed in water, the oil floats at the top. The density of oil-based hydraulic fluid is very similar to that of water.
Synthetic hydraulic fluid was invented in the 1950s. It’s also known as “synthetic oil” or “hydrocarbon based fluid.”
Unlike oil-based hydraulic fluid, synthetic hydraulic fluid doesn’t float in water. Instead, it sinks to the bottom.
Oil-Based Hydraulic Fluid
Aircraft engine oil (also called “aviation engine oil”): This is an oil that contains additives designed to prevent corrosion, wear, and sludge formation within the engine’s cylinders.
It also helps lubricate moving parts, including pistons, valves, bearings, etc., and acts as a sealant for piston rings.
Aviation engine oil is often referred to by its trade name, “Avgas”. Avgas comes in several grades based on the quality of the fuel it can be mixed with.
For example, Grade I avgas can only mix with grade I avgas; grade II avgas can mix with grade II avgas.
Synthetic Hydraulic Fluid
Synthetic oil: This is a liquid that contains no petroleum products. Instead, it is made from chemicals that are similar to those found in crude oil.
Synthetic oils are more expensive than traditional mineral oils, but they have many advantages over them.
They do not contain sulfur, which makes them environmentally friendly. They do not contaminate water supplies, unlike mineral oils.
And they are much less likely to break down into harmful fumes when exposed to heat or flame.
In addition, synthetic oils are very stable at high temperatures. Because of these qualities, synthetic oils are widely used in industrial applications.
Hydraulic fluid is usually stored in large containers called reservoirs. These reservoirs may be located inside the aircraft or outside the aircraft.
If the reservoir is located inside the aircraft, it will most likely be part of the cockpit equipment.
However, if the reservoir is located outside the aircraft, it will probably be part of the cargo area.
Hydraulic fluid reservoirs are generally classified according to their size. Small reservoirs hold about 1 quart of fluid.
Large reservoirs hold about 2 quarts of fluid. Some aircraft use small reservoirs because they are easier to carry around.
Others use large reservoirs because they are easier for passengers to access.
The amount of fluid needed depends on how the aircraft is being operated.
Aircraft manufacturers recommend different amounts of fluid for each flight.
For example, some aircraft require 10 percent more fluid during takeoff than they do during normal operation.
When you fill your aircraft’s reservoir, make sure that you follow all the manufacturer’s recommendations regarding the correct amount of fluid.
Otherwise, the system could fail.
The Difference Between Colors
Synthetic hydraulic fluid comes in three different colors: green, yellow, and red.
Green is the most common color because it’s easy to see. Yellow and red are less visible than green.
When you look at the inside of an airplane engine, you will notice that the oil reservoir looks like a big round tank.
On the side of this tank is a valve that allows air to enter and exit the system. Inside the valve is a small metal ball called a piston.
As the piston moves up and down, it pushes the oil through the system. When the piston is pushed all the way down, the oil fills the engine.
When the piston is pulled back up, the oil drains out of the engine. You may notice that the piston moves slowly when the engine is cold.
That’s because the oil isn’t flowing fast enough to push the piston up and down quickly. Once the engine warms up, the piston starts moving faster.
How To Tell If Your Aircraft Engine Has Air Leaks
If your engine seems to run slower than normal, check under the hood. Look for any leaks in the engine compartment.
There should be clear plastic tubing running across the engine. If you spot any cracks or holes, repair them immediately.
If you don’t know how to do this, ask your mechanic or pilot. He or she will be able to tell you what needs to be done.
What Is Hydraulic Fluid Contamination?
Hydraulic fluid contamination is when particles, debris, or water enter into the hydraulic system.
This causes serious problems such as less efficient operation, costly repair and even failure.
Contamination can occur due to leaks, spills, improper maintenance or other reasons.
Contaminated fluids cause serious damage to engines, fuel systems and other components.
In order to prevent contamination, it is important to maintain proper storage conditions.
It is also necessary to keep the aircraft away from sources of moisture.
Why Do I Need A Hydraulic System Check?
Aircraft mechanics perform regular checks on the hydraulic system to ensure its safety and efficiency.
These checks include inspecting the valves, hoses, pumps, filters, and tanks. They also test the pressure and flow rate of the system.
Aircraft mechanics use special tools to inspect these parts. One type of tool is called a leak detector. This device has a hose attached to it.
The mechanic then inserts the end of the hose into the system.
If there is a leak, the technician will hear a sound similar to the noise made by a dripping faucet.
Another tool used to check the system is called a pump tester. This device measures the pressure and flow rate in the system.
There are many things that can go wrong with the hydraulic system. Some of these issues include:
- Leaks – If the system contains leaks, it will not work properly.
- Air Bubbles – If the system contains air bubbles, they could cause the system to fail.
- Overpressure – If the system contains overpressure, it will not function correctly.
- Low Pressure – If the system contains low pressure, it will not operate efficiently.
In addition to checking the system, pilots need to make sure their aircraft is safe.
Pilots must follow all FAA regulations and guidelines. They must also have an emergency plan in place.
FAA Regulations For Aviation Mechanics
The Federal Aviation Administration (FAA) regulates the activities of people who fly airplanes.
The agency oversees the licensing process, flight training requirements and certifications.
The FAA requires that pilots obtain at least 20 hours of flight time before they can take a private pilot license exam.
After passing the exam, pilots receive a certificate.
Aviation mechanics (see also “How Much Do Aviation Mechanics Make?“) play a vital role in keeping aircraft flying safely.
They perform routine inspections to ensure the safety of passengers and crew members. Hydraulic fluid should always be checked and healthy.