Which types of hydraulic fluid are currently used in civil aircraft?

The use of hydraulic fluid in civil aircraft is important for the proper operation of hydraulic systems, which are essential for controlling various aircraft functions such as landing gear operation, flight control surfaces, and braking systems.

Phosphate ester-based fluids, vegetable-based fluids, and mineral-based fluids are all utilized in civil aircraft due to their specific properties that cater to different requirements. Phosphate ester-based fluids are known for their high heat resistance and fire safety characteristics, making them suitable for high-performance applications.

Vegetable-based fluids, while not as common, provide biodegradable options that are more environmentally friendly. Mineral-based fluids are widely used due to their cost-effectiveness and good lubricating properties, making them suitable for various hydraulic applications in aircraft.

The combination of these fluid types provides versatility and allows aircraft manufacturers to choose the most appropriate hydraulic fluid based on specific system demands, ensuring safety and efficiency in operation.