The application of fluorosilicone oil in aircraft hydraulic systems requires a clear distinction between "fuel resistance" and "hydraulic fluid resistance." The user's question mentions "fuel resistance performance," but the medium used in aircraft hydraulic systems is aviation hydraulic fluid (such as Skydrol phosphate ester hydraulic fluid, MIL-H-83282, etc.), not aviation fuel (Jet A/JP-8). Therefore, this answer focuses on the resistance performance of fluorosilicone oil to hydraulic fluid in hydraulic systems, not fuel systems.

Core Conclusion: Fluorosilicone oil is not widely certified for use in aircraft hydraulic systems.
Although fluorosilicone oil possesses excellent oil resistance and thermal stability in terms of its chemical structure, it has not yet been officially approved by mainstream manufacturers such as Boeing and Airbus or authoritative standards (such as AMS, MIL-SPEC) for use in sealing components of aircraft hydraulic systems in the aviation industry. Its application is still limited to laboratory research, non-critical auxiliary seals, or as a modifier additive for fluororubber, rather than as an independent engineering material. Hydraulic Fluid Resistance Performance
Performance Dimension | Fluorosilicone Oil Performance | Comparative Material (FKM) | Data Source
Chemical Compatibility | Good compatibility with Skydrol phosphate ester hydraulic fluid and silicate ester hydraulic fluid, with no significant swelling or degradation | Excellent compatibility with Skydrol, the industry standard material |
Temperature Resistance Range | Long-term use: -50℃ to +180℃; short-term up to 200℃ | Typical range: -20℃ to +200℃ |
Volume Change Rate | No publicly available test data under dynamic sealing conditions | MIL-H-83282 standard requires ≤5% volume expansion | —
Compression Set | No independent test data available; a patent shows that fluorosilicone oil can be used as an additive to reduce the compression set of FKM | FKM under 150℃ × 22h conditions: 20–40% |
Dynamic Sealing Performance | No publicly available data on friction coefficient, leakage, and extrusion resistance under reciprocating motion conditions | FKM performs stably in high-pressure reciprocating seals, conforming to SAE AS1241 IV | —
Note: Fluorosilicone oil performs well in static sealing, but in high-frequency reciprocating motion in hydraulic systems (such as piston rod seals), the lack of dynamic performance verification data meeting aviation standards is the core bottleneck preventing its certification.

Industry Standards and Manufacturer Specifications
AMS 7276 / SAE AS3208A: Explicitly specifies the use of fluorocarbon rubber (FKM) or perfluoroelastomer (FFKM) as hydraulic system sealing materials, and does not mention fluorosilicone oil.
MIL-H-83282: Aviation hydraulic fluid specification, requiring sealing materials to pass tests for oil resistance, compression set, and low-temperature elasticity. Fluorosilicone oil has no official certification record.
Boeing/Airbus Technical Manuals: No official selection or approval list of fluorosilicone oil as a hydraulic sealing material has been found in publicly available documents.
Skydrol Compatibility: Although some literature indicates that Skydrol LD-4 is "compatible with most elastomers," it does not explicitly include fluorosilicone rubber. Current Status and Limitations of Engineering Applications
Limited market applications: Industrial platforms such as Baidu AiPurchasing did not find standardized products for fluorosilicone hydraulic seals, indicating that a complete industrial supply chain has not yet been established.
No failure cases, but also no successful cases: Searches did not reveal any failure reports of fluorosilicone due to incompatibility in hydraulic systems, nor were any engineering cases of actual application in commercial aircraft models found.
Technical alternative paths: Patents show that ethylene fluorosilicone, when used as an additive, can improve the compression set of fluororubber, indicating its value lies in auxiliary modification rather than independent use.
Rich media component insertion
Note: The above image components show the general structure of hydraulic seals, actual fluororubber O-rings, and installation diagrams. Although not specific to fluorosilicone, these are the most relevant visual materials currently available, reflecting the typical form of hydraulic system seals.

Conclusion
Although fluorosilicone has the potential to withstand aviation hydraulic fluid in terms of its chemical structure, it has not yet become an engineering-applicable sealing material in aircraft hydraulic systems. While its resistance to hydraulic fluid is superior to ordinary silicone rubber, it cannot compete with fluororubber (FKM) in three core dimensions: dynamic performance, standard compliance, and manufacturer certification. Therefore, fluorosilicone does not currently have the engineering status to replace FKM in aviation hydraulic systems.