What is the Importance of Seals and Gaskets in Aircraft?

Leak prevention, Consistent pressure, Component protection, Ensure functionality

Aircraft Seals and Gaskets

Aerospace seals and gaskets are vital to the efficient and safe operation of both commercial and military aircraft by preventing leakage, protecting sensitive systems, and maintaining stable pressures. We will provide an overview of the importance of aircraft gaskets and seals, the materials they are made of, their common applications, and RD Rubber’s custom rubber molding capabilities.

Importance of Seals and Gaskets in Aircraft

The aerospace industry requires components that can withstand extremely challenging conditions. Unlike many other materials, thermoset elastomers offer an impressive combination of strength, flexibility, and durability. In applications where safety and reliability are paramount, elastomer seals deliver the necessary dependable performance.

Aircraft seals and gaskets offer the following key benefits:

Leak prevention. Gaskets and seals help protect systems from possible leakage of hydraulic fluids, fuel, oil, and other fluids that might otherwise put equipment and passengers at risk.
Consistent pressure. Pressurized cabins rely on aircraft seals and gaskets to maintain safe and comfortable pressure levels.
Component protection. Another function of aerospace seals and gaskets is to protect other essential aircraft parts from sources of wear or contaminants, such as dust, dirt, and moisture.
Ensure functionality. Proper seals and gaskets also maintain the integrity of various aircraft systems, including fuel, hydraulic, and engine systems.

High-Performance Aerospace Elastomers: Viton, FKM, EPDM, Silicone

Aircraft gaskets and seals may use different materials, depending on the application. The three most common material types are the following:

Viton^®. Many aircraft seals and gaskets consist of Viton rubber, which is a type of fluorocarbon elastomer manufactured by Chemours that offers superior temperature, oil, and fuel resistance. Viton rubber gaskets work well in aircraft fuel systems and engines.
Fluoroelastomer (FKM). Many aircraft seals and gaskets consist of FKM rubber, which offers superior temperature, oil, and fuel resistance. FKM rubber gaskets work well in aircraft fuel systems and engines.
EPDM. Ethylene propylene diene monomer (EPDM) rubber is a type of elastomer that provides reliable resistance to weathering, chemicals, and ozone, making it ideal for use in air conditioning and fuel systems.
Silicone. Another option is silicone rubber, a highly versatile elastomer that provides low compression set and excellent resistance to chemicals and high temperatures. Cockpit seals and electrical connectors frequently comprise silicone rubber gaskets.

Types and Applications of Aircraft Seals and Gaskets

Types

Thermal Insulation and Protection

Aerospace equipment must function correctly at high altitudes, where it is exposed to very low temperatures. Since rubber maintains its physical properties even under extreme temperature fluctuations, it is an ideal material for ensuring thermal protection.

In addition, rubber’s ability to withstand compression makes it an optimal choice for seals within pneumatic and hydraulic systems. Components like landing gear and wing flaps can close tightly, compressing the seals without damaging them.

Critical-to-Function Equipment

Since rubber is a fire-retardant and grounding material, it is an excellent solution for protecting crucial electronic components and other mission-critical equipment. Rubber seals also play an important role in keeping contaminants out of instrument panels, cockpit electrical systems, and other motion control, navigation, and communication systems. In addition, they protect printed circuit boards from the risks associated with extreme altitude.

Applications

Being lightweight and durable, aerospace elastomer seals are used throughout an extensive number of applications. Here are some of the potential applications for aircraft seals and gaskets.

Engines

Engines often use seals and gaskets for pistons and valves. In pistons, seals prevent leaks between the cylinder walls and the piston. In valves, gaskets close the gap between the valve and the valve seat.

Fuel Systems

Fuel systems also benefit from using aerospace seals and gaskets. For example, seals can keep fuel lines and hoses from leaking fuel. They protect against fuel contamination and evaporation in fuel tanks. Fuel pumps also have gaskets to prevent leaks and seal housings.

Hydraulic Systems

In a hydraulic system, rubber gaskets seal the space between cylinder walls and the piston, as well as the space in valve ports. Hydraulic lines also rely on seals to prevent leakage of hydraulic fluid.

Avionics

Avionics need strong seals for various components. Rubber seals prevent the incursion of dust, moisture, and other contaminants into avionics systems, which could interfere with the proper operation of electronic systems in everything from commercial passenger jets to military fighter aircraft.

Technical Specifications & Standards for Aerospace Seals

Elastomer seals used in the aerospace industry are subject to numerous safety and quality requirements. The standards for aerospace seals are issued by the Society of Automotive Engineering (SAE). They cover everything from product shelf life restrictions to design recommendations and more.

AS5316

This aerospace standard covers elastomeric seal components. It provides a control document for organizations that require one and includes shelf-life restrictions consistent with data from age-control cumulative experiments. In addition, AS5316 outlines the requirements for traceability and proper storage for elastomeric seal components. It also includes a technical paper that addresses seals specifically, rather than other types of rubber components.

Mil-G-5514

The Mil-G-5524 specification outlines basic design criteria recommendations for gaskets, packings, and packing and gasket glands. It also covers related features for use in hydraulic equipment systems that have been designed in accordance with the MIL-H-5440 classification. However, Mil-G-5514 is only used for legacy applications and not new aircraft designs. New applications obtain seal glad requirements from either AS4716 or AS5857.

AS4716

This SAE standard specifies the gland or groove design criteria. It also outlines specifications for dynamic and static O-ring seal glands, in addition to other seals. Under this criteria, glands are sized to ensure sufficient squeeze for effective sealing while still allowing adequate operation in dynamic operations. However, this standard does not apply to static external applications, which must instead meet AS5857 requirements.

AS5857

This SAE standard outlines the standardized gland design criteria and dimensions for elastomeric seal glands for static applications. Under this standard, glands are sized to facilitate increased squeeze compared to AS4716. This results in more effective sealing under low temperatures and low seal swell conditions.

AS6235

The AS6235 standard outlines the standardized gland design dimensions and other criteria for static face seals used within internal pressure and external pressure hydraulic and pneumatic aerospace applications. These glands are designed using AS568 size elastomeric O-rings with Class 2 tolerances at nominal operating pressures up to 3000 psi (20690 kPa). They are also circular in shape and do not utilize anti-extrusion (backup rings).

Partner With a Trusted Aerospace Seals Manufacturer

If you’re seeking dependable aircraft seals and gaskets, RD Rubber Technology offers custom-designed solutions for your specific aerospace project. We supply a wide range of custom rubber products, including aerospace seals, gaskets, grommets, latches, valves, and other critical to function products. Our AS9100:2016 certification ensures we meet the stringent quality standards required for commercial aviation, while our DOD JCP and CMMC Level 2 (self assessed) certifications, ITAR registration, and NIST 800-171 compliance make us a trusted partner for defense and military contractors. Additionally, we maintain ISO 9001:2015 quality system certification. RD Rubber is dedicated to meeting your requirements through our comprehensive product development and production capabilities.