Fluorosilicone oil, with its unique molecular structure—containing both carbon-fluorine (C–F) and silicon-oxygen (Si–O) bonds—has become an indispensable high-performance material in aviation fuel systems.  It is widely used in sealing and lubrication applications under extreme temperatures and harsh solvent environments, exhibiting significantly superior overall performance compared to traditional silicone and fluororubber.

Sealing Applications: Key Components and Performance Advantages
Fluorosilicone oil is primarily used in the form of fluorosilicone rubber for static and dynamic sealing in aviation fuel systems. Its core applications include:

Aircraft Fuel Tank Sealing Rings: Directly in contact with aviation fuel (Jet A, JP-8), exhibiting extremely low volume change after long-term immersion, maintaining structural integrity.
Fuel Hydraulic System O-rings: Used in fuel pumps, fuel control valves, and pipe joints, operating within a temperature range of -68℃ to +232℃, making it the only elastomer currently capable of withstanding non-polar fuels across this wide temperature range.
High-Pressure Fuel Line Connectors: Maintains reliable sealing under a static pressure of 5 MPa, exhibiting excellent ozone aging resistance, suitable for high-altitude, low-oxygen, and strong ultraviolet radiation environments.
Its media resistance far surpasses that of ordinary silicone and fluororubber: after 500 hours of immersion in a gasoline/methanol (85:15) mixed fuel, there is no significant deterioration in hardness, tensile strength, or volume change.

Lubrication Applications: Low and High-Temperature Protection for Precision Components
Fluorosilicone oil, as a base component of synthetic lubricants, is primarily used in dynamic components of aviation fuel systems that require extremely high lubrication and stability:

Fuel Pump Internal Sliding Surfaces: Lubricates the contact surfaces of the fuel pump rotor, plunger, and casing, reducing wear and extending service life.
Fuel Metering Devices and Control Valves: Forms a stable oil film in tiny gaps, ensuring precise control of fuel flow and preventing sticking or response delays caused by insufficient lubrication. Low-Temperature Starting System: Maintains low viscosity and excellent fluidity even in extreme low-temperature environments of -55°C, ensuring smooth fuel supply during engine cold starts.
Its thermal oxidative stability reaches 250°C, far exceeding that of ester-based lubricants (approximately 200°C), and it exhibits excellent viscosity-temperature performance, maintaining a stable lubricating film over a wide temperature range, reducing energy consumption and component temperature rise.

Chemical Compatibility and Resistance: Excellent performance in aviation fuel environments
Fluorosilicone oil exhibits excellent chemical compatibility with mainstream aviation fuels (Jet A, JP-8, Jet A-1), and its resistance is demonstrated by:

Performance Indicator | Fluorosilicone Oil Performance | Comparative Material Performance
Fuel Immersion Resistance | No swelling or softening after long-term contact at 232°C | Ordinary silicone rubber: easily swells; fluororubber: low-temperature embrittlement
Methanol Gasoline Resistance | Physical properties remain almost unchanged after 500 hours in gasoline/methanol (85:15) | Fluororubber: volume expansion rate > 5%
Thermal Oxidative Stability | Stable at 250°C, decomposition temperature > 300°C | Ordinary silicone rubber: aging starts at 200°C
Low-Temperature Brittleness | Brittleness temperature as low as -89°C | Fluororubber: approximately -30°C
This characteristic makes it the only elastomer material that meets the requirements for resistance to non-polar media across the entire temperature range of -68°C to 232°C.