AS3208-06 - 75 Durometer FKM O-Ring for Fuel & Lubricant Systems

AS3208-06 – 75 Durometer FKM O-Ring for Fuel & Lubricant Systems

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The AS3208-06 is a high-performance, preformed packing O-ring manufactured in strict accordance with SAE Aerospace Standard AS3208. This standard specifies O-rings made from a 75 durometer Fluorocarbon (FKM) elastomer, a material widely known by the trade name Viton®. This component is a flight-critical seal engineered for demanding applications in aircraft fuel and high-temperature lubrication systems, where it must resist degradation from hydrocarbon fuels, synthetic oils, and high heat.

This O-ring is dimensionally equivalent to the AS568-006 standard size. The AS3208 specification, however, imposes stringent quality controls and material traceability required for certified aircraft use. It is a fundamental component for sealing fittings, housings, and components in petroleum-based fluid systems. It is dimensionally and functionally similar to M83248/1-006 and AS3209-006 O-rings.

Key Features

• SAE Aerospace Standard (AS) Certified: Manufactured to the exact material, hardness, and dimensional tolerances of the AS3208 specification.

• Fluorocarbon (FKM/Viton®) Construction: Provides superior resistance to aromatic hydrocarbon fuels (Avgas, Jet A/A-1), synthetic lubricants (turbine oils), petroleum-based hydraulic fluids, and high temperatures.

• 75 Durometer Hardness: Offers an optimal balance of flexibility for sealing and hardness for durability and resistance to deformation under pressure.

• Excellent Thermal Stability: Maintains sealing integrity and physical properties at continuous operating temperatures up to 400°F (204°C).

• Low Compression Set: Exhibits excellent resistance to taking a permanent set after being compressed at high temperatures, ensuring a reliable, long-lasting seal.

Technical Specifications

• Part Number: AS3208-06

• Component Type: Preformed Packing, O-Ring

• Governing Specification: AS3208

• Material: Fluorocarbon Rubber (FKM), Viton®.

• Hardness: 75 ± 5 Durometer Shore A.

• Size (AS568A Dash Number): -006

• Dimensions:

  • Inside Diameter (ID): 0.114 inches (2.90 mm)

  • Cross-Section (CS): 0.070 inches (1.78 mm)

• Typical Operating Temperature Range: -15°F to 400°F (-26°C to 204°C).

• Common Cross-References: M83248/1-006, AS3209-006, NAS1593-006

Aircraft Compatibility

The AS3208-06 is a standard hardware component used in countless fuel, oil, and hydraulic systems across all categories of certified aircraft from all major manufacturers, including Textron, Piper, Boeing, Airbus, and others where this size and material are specified.

Crucial Note: The correct part number for a specific application must be verified against the Illustrated Parts Catalog (IPC) or Component Maintenance Manual (CMM) for the component or aircraft being serviced.

Applications

This O-ring is specified for static sealing in systems requiring high-temperature and hydrocarbon fluid resistance. Common uses include:

• Aircraft Fuel Systems: Fuel injector nozzle seals, fuel line fittings, and fuel control unit/pump housing seals.

• Engine Lubrication Systems: Sealing in high-temperature oil system components, filter housings, and accessory case fittings.

• Hydraulic Systems utilizing compatible synthetic hydrocarbon-based fluids (e.g., MIL-PRF-83282).

• Firewall-Forward fluid connections.

Why Choose AS3208-06?

Choosing a genuine, certified AS3208-06 O-ring is a critical decision for system safety and reliability. Fluid and elastomer compatibility is a fundamental principle of aircraft maintenance. Installing an incorrect O-ring material, such as a Nitrile (Buna-N) seal in a high-temperature synthetic oil or fuel system, will result in rapid chemical degradation, hardening, cracking, and seal failure, leading to a critical fluid leak. The AS3208 military specification guarantees the correct 75-durometer FKM material, traceability, and quality control required for a safe, durable, and reliable seal.

The exceptional chemical and thermal stability of the AS3208-06 Fluorocarbon (FKM) O-ring is derived from the molecular structure of the fluoropolymer from which it is made. Its robustness comes from the immense strength of its carbon-fluorine (C-F) bonds, which are among the strongest single bonds in organic chemistry. This fluorine sheath effectively shields the polymer's carbon backbone from chemical attack by non-polar fluids like aromatic hydrocarbons (in jet fuel) and synthetic ester-based lubricants (turbine oils), which would readily break down the polar backbone of an incompatible elastomer like Nitrile. This same C-F bond strength is the source of FKM's high-temperature resistance, allowing it to maintain its sealing force and resist a compression set (permanent flattening) at temperatures where other elastomers would fail.

Note: O-rings are typically considered single-use components in aerospace applications. These components have a finite shelf life (cure date) which must be strictly observed. CRITICAL: Ensure the correct elastomer type (FKM) and durometer (75) are used for the application per the maintenance manual. Do NOT install a Nitrile (Buna-N) O-ring in a high-temperature or synthetic fluid system. Do NOT install this FKM O-ring in a phosphate ester (Skydrol®) system, which requires EPDM. Installation must be performed by a certified A&P mechanic.

Documentation

The definitive technical requirements for this component are detailed in SAE Aerospace Standard AS3208. These proprietary documents must be sourced directly from the relevant standards organizations for complete engineering specifications.