M83248/1-011 – 75 Durometer FKM O-Ring for Fuel & Lubricant Systems
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The M83248/1-011 is a high-performance, preformed packing O-ring manufactured in strict accordance with Military Specification MIL-PRF-83248, Type 1, Class 1. This is a flight-critical seal, engineered for demanding applications in aircraft fuel and high-temperature lubrication systems. It is fabricated from a 75 durometer Fluorocarbon (FKM) elastomer, widely known by the trade name Viton®. This specific material is mandated for its exceptional resistance to the degrading effects of hydrocarbon fuels, synthetic turbine oils, and high temperatures.
This O-ring is dimensionally equivalent to the AS568-011 standard size. The M83248/1 specification, however, imposes more stringent quality controls, material traceability, and performance requirements (such as low compression set) than general-purpose industrial O-rings, making it the certified standard for flight-critical applications. Its integrity is essential for preventing leaks in fuel-system components, engine accessories, and hydraulic systems.
Key Features
Military Specification (MIL-PRF-83248) Certified: Guarantees adherence to stringent material, dimensional, tolerance, and quality requirements for aerospace and defense applications.
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: M83248/1-011
Component Type: Preformed Packing, O-Ring
Governing Specification: MIL-PRF-83248, Type 1 (75 Durometer), Class 1.
Material: Fluorocarbon Rubber (FKM), Viton®.
Hardness: 75 ± 5 Durometer Shore A.
Size (AS568A Dash Number): -011
Dimensions:
Inside Diameter (ID): 0.301 inches (7.65 mm)
Cross-Section (CS): 0.070 inches (1.78 mm)
Typical Operating Temperature Range: -15°F to 400°F (-26°C to 204°C).
Cross-References: AS3209-011, AMS7276-011
Aircraft Compatibility
The M83248/1-011 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 (Cessna, Beechcraft), 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 cap seals, 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 M83248/1-011?
Choosing a genuine, certified M83248/1-011 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 M83248/1 military specification guarantees the correct 75-durometer FKM material, traceability, and quality control required for a safe, durable, and reliable seal in these chemically aggressive and high-temperature environments.
The exceptional chemical and thermal stability of the M83248/1-011 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. During polymerization, fluorine atoms, which are highly electronegative, form a protective, non-reactive sheath around the vulnerable carbon backbone of the polymer chain. This fluorine sheath effectively shields the polymer's 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 Military Specification MIL-PRF-83248. These proprietary documents must be sourced directly from the relevant standards organizations for complete engineering specifications.