AS3209-012 – Textron Aviation OEM Fluorocarbon (Viton®) Boss Seal O-Ring
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Overview
The AS3209-012 is a high-performance, preformed O-ring packing seal that holds dual authority as a component built to the exacting Aerospace Standard (AS3209) and as a genuine Textron Aviation Original Equipment Manufacturer (OEM) part. This O-ring is fabricated from a Fluorocarbon (FKM) elastomer, a material widely known by its DuPont trade name, Viton®, and is specifically engineered for creating a static seal on -6 size straight thread tube fittings in high-temperature system bosses.
The FKM material gives this O-ring an exceptional operational temperature range, up to 400°F (204°C), making it the specified component for applications where standard Nitrile (NBR) O-rings would fail due to heat degradation. As a genuine Textron Aviation part, this AS3209-012 seal is the factory-specified component for numerous high-temperature connections on Cessna, Beechcraft, and Hawker aircraft, guaranteeing the correct material compound and performance.
Key Features
Textron Aviation OEM Certified: Guarantees the part is the factory-approved, fully traceable component for the Textron Aviation family of aircraft.
High-Temperature Fluorocarbon (FKM): Fabricated from a Viton® or equivalent FKM elastomer, providing a continuous service temperature rating of up to 400°F (204°C).
Designed for -6 Boss Seals: Specifically sized (AS568-012) for static axial sealing of -6 (3/8") tube fittings in their corresponding ports.
Excellent Fluid Resistance: Offers superior chemical resistance to a wide range of petroleum-based and synthetic lubricating oils, hydraulic fluids, and jet fuels.
75 Durometer Hardness: The 75 Shore A hardness provides an excellent balance of sealing force and resistance to deformation for standard pressure applications.
AS Standard Compliance: Meets all dimensional, material, and quality requirements of AS3209, ensuring airworthiness and interchangeability.
Technical Specifications
Part Number: AS3209-012
Component Type: Preformed O-Ring Packing, Boss Seal
OEM Authority: Textron Aviation
Governing Specification: AS3209
Material: Fluorocarbon Elastomer (FKM / Viton®)
Hardness: 75 ± 5 Durometer Shore A
Color (Typical): Brown
Dimensions (AS568-012):
Inside Diameter (ID): 0.364 inches
Cross-Section (CS): 0.070 inches
Typical Temperature Range: -15°F to +400°F (-26°C to +204°C)
Aircraft Compatibility
As a Textron Aviation OEM part, this O-ring is specified for numerous high-temperature fluid connections on their aircraft. The underlying AS standard makes it common across the industry.
Primary Textron Aviation Platforms:
Cessna Citation Series Business Jets
Beechcraft King Air Series
Hawker Business Jets
General Aerospace Usage: Used in any aerospace application requiring a high-temperature resistant boss seal for a -012 size fitting.
Note: Verification of applicability is the responsibility of the installer. Always consult the current version of the aircraft or engine's Illustrated Parts Catalog (IPC) to confirm part number eligibility.
Applications
Sealing of common -6 size (9/16-18 thread) straight thread tube fittings on firewall-forward components.
Connections on engine accessories such as fuel control units, oil filter housings, and hydraulic pumps.
Hydraulic and fuel lines located in close proximity to high-temperature bleed air ducts or exhaust components.
Why Choose this AS3209-012?
This component provides the dual assurance of meeting the public AS aerospace standard and the specific endorsement of Textron Aviation. This guarantees the seal's physical properties and, critically, ensures that the specific FKM compound used is the one tested and approved for the system fluids on Textron aircraft. Using the genuine OEM part is the only way to guarantee you are installing the correct, certified high-temperature material required for a safe and airworthy repair.
A critical aspect of airworthiness for an elastomeric seal like the AS3209-012 is its finite shelf life, which is determined by its cure date. Aerospace standard ARP5316 provides the guidelines for the storage and age control of aerospace elastomers. An O-ring is not an inert piece of hardware; its polymer structure is subject to slow, irreversible chemical changes over time from exposure to oxygen, ozone, and UV light, even in storage. These changes cause the material to harden, lose its elasticity, and develop a higher compression set. For this reason, every certified aerospace O-ring is marked on its packaging with the quarter and year it was vulcanized (cured). A mechanic must verify that the O-ring is within its specified shelf life (e.g., 10-15 years for FKM, depending on storage conditions) before it can be legally installed. Installing an expired O-ring, even if it appears new, introduces a significant risk of premature seal failure.
Note: This component has a finite shelf life defined by standards like ARP5316. The cure date marked on the packaging must be verified prior to installation. It is a single-use part; a new O-ring must be used every time a fitting is reinstalled. The port and fitting sealing surfaces must be impeccably clean and free of scratches or damage. The O-ring must be lubricated with clean system fluid before installation.
Documentation
The base standard for this part is the Aerospace Standard AS3209. This is a controlled document managed by SAE International. OEM-specific application and installation data is contained within the Textron Aviation maintenance and parts manuals.