A Complete Guide to Flame Retardant Silicone Rubber (Aerospace Specification)

What is Aerospace Specification Flame Retardant Silicone Rubber?

Aerospace specification flame retardant silicone rubber is a specialised form of silicone designed to meet the rigorous safety, performance and regulatory requirements of the aerospace industry. It provides exceptional thermal stability, mechanical resilience and resistance to extreme environmental conditions while also complying with stringent flammability, smoke and toxicity (FST) standards. This makes it ideal for applications where fire safety and reliability are important.

These materials have been independently tested and are certified to the following FAR/JAR 25.853 specifications:

F1 – Flammability CS25.853 (a) Amdt.18 App.F Pt.I(a)(1)(i) & (b)(4) 60s Vertical Burn *
F3 – Flammability CS 25.853(a) Amdt.18 App.F Pt.I(a)(1)(iv) & (b)(5) 15s Horizontal Burn *
F4 – Flammability CS 25.853(a) Amdt.18 App.F Pt.I(a)(1)(v) & (b)(5) 15s Horizontal Burn
F5 – Flammability CS.25.853(a) Amdt.18 App.F Pt.I(a)(2)(ii) & (b)(6) 30s/45° Burn *
F9 – Smoke Emission ABD0031 IssF *
F10 – Toxic Gas Emission ABD0031 (ppm) IddF *

* indicates that only certain compound hardnesses are certified to this specification.

These certifications ensure that our flame retardant silicone rubber meets the safety requirements necessary for aerospace applications, helping to reduce fire hazards and increase passenger safety.

Appearance

Off-white so accepts limited pigmentation.

Tear Strength

  Resistance to tearing between 14.5N/mm and 27N/mm.

Density

  Formulated for a density of between 1.12 g/cm3 and 1.2g/cm3.

Hardness

Available between 20ᵒ Shore A and 80ᵒ Shore A.  

Tensile Strength

  Tensile strength between 8.6N/mm2 and 11.6N/mm2.  

Elongation at Break

  Flexibility between 460% and 671% without breaking.  

Temperature Range

  Operates effectively between -50°C and 220°C.  

Compression Set

  Recovery from deformation between 27% and 40%.

Learn how aerospace specification silicone is formulated, how it differs from other specialist grades and common applications within the industry.

How is Aerospace Flame Retardant Silicone Rubber Made?

The production of aerospace-grade flame retardant silicone starts with high-purity polydimethylsiloxane (PDMS) as the base polymer. Reinforcing fillers, such as silica, are incorporated to improve mechanical properties and enhance resistance to wear and degradation. To achieve its flame-retardant properties additives, such as halogen-free flame retardants, are blended into the formulation.

The material undergoes a controlled curing process using either peroxide or platinum-based catalysts to create a strong cross-linked structure. This vulcanisation process ensures high elasticity, stability and durability under extreme temperatures. The cured rubber is then subjected to rigorous testing to confirm compliance with aerospace safety standards, including flammability, smoke emission and toxic gas release thresholds.

Custom formulations can be developed to meet specific hardness, colour and mechanical property requirements while ensuring compliance with all necessary aerospace regulations. The material is available in various forms, such as sheets, extruded profiles and moulded components, to fit diverse application needs.

Mixing aerospace specification silicone

Advantages of Aerospace Flame Retardant Silicone Rubber

This aerospace specification silicone offers several advantages over other specialised grades that make it an essential material for the aerospace industry. Its ability to withstand extreme temperature variations, ranging from -50°C to 220°C, ensures reliability in both high-altitude and engine-adjacent environments. This thermal stability helps maintain the integrity of rubber seals, gaskets and insulating components.

The materials fire-resistant properties significantly reduce the risk of ignition and flame propagation, contributing to overall cabin safety. Its compliance with FAR/JAR 25.853 and ABD0031 standards ensures that it meets stringent aviation industry regulations for flammability, smoke and toxic emissions, providing added safety for passengers and crew.

Furthermore, aerospace-grade flame retardant silicone rubber exhibits excellent resistance to environmental degradation, including UV radiation, ozone and exposure to aviation fluids. Its durability and long service life make it a cost-effective solution for aerospace applications, reducing maintenance and replacement costs over time.

Silicone rubber extrusions in a range of colours

Common Applications and Uses

Aerospace specification flame retardant silicone is utilised in a wide range of applications within the aerospace industry where safety and performance are important. Below are three key application areas:

Industries

Aircraft Cabin Interiors

In aircraft cabin interiors, this material is used for rubber seals, gaskets and insulation components in overhead compartments, wall panels and seating structures. Its flame retardant properties ensure compliance with aviation safety regulations, reducing the risk of fire-related incidents. The materials flexibility and resistance to compression set help maintain effective sealing performance over extended periods.

 Engine and Propulsion Systems

In engine and propulsion systems, flame retardant silicone rubber is employed in high-temperature seals, vibration dampers and fire-resistant barriers. Its ability to withstand extreme heat and mechanical stress makes it ideal for components used in and around aircraft engines, ensuring long-term durability and reliable performance under demanding conditions.

 Electrical and Avionics Insulation

In electrical and avionics insulation, the material is used for protective coverings, shielding gaskets, and thermal insulation for wiring and electrical enclosures. Its combination of electrical insulating properties and resistance to flammability enhances the safety and reliability of avionics systems, preventing short circuits and reducing fire risks in aircraft electronics.

Material Compound Datasheets

Flame retardant silicone can be extruded in a range of different hardnesses, each suitable for different applications. The properties and characteristics of these hardnesses may differ. Please see the downloadable PDF material compound datasheets for this information.

20 Shore A

30 Shore A

40 Shore A

50 Shore A

60 Shore A

70 Shore A

80 Shore A

Looking for a different grade of Silicone?

As well as aerospace silicone, we are also able to manufacture rubber sealing products in a selection of other specialised Silicone compounds. This includes general purpose silicone, metal detectable silicone, high temperature silicone and rail flame retardant silicone.

Other Silicone Grades

Contact Us

With over 50 years' experience in the rubber sealing industry, our team has extensive experience in finding sealing solutions for our customers. Contact our experts via phone or email for sealing advice or bespoke quotations.