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MS28775-269 – Textron Aviation OEM Preformed Packing O-Ring
Available now on the Airparts.aero Marketplace.
Overview
The MS28775-269 is a military-standard, large-diameter preformed packing O-ring, engineered for high-performance static sealing in aerospace fuel, oil, and hydraulic systems. As specified for use on Textron Aviation aircraft, this O-ring is manufactured in strict accordance with military specifications (such as MIL-R-83248). It is fabricated from a high-quality Fluorocarbon (FKM) synthetic rubber, commonly known by the trade name Viton®, chosen for its excellent resistance to a wide range of fluids and its ability to maintain sealing integrity at elevated temperatures.
Key Features
- High-Temperature Fluorocarbon (FKM) Material: Fabricated from a Viton® (FKM) elastomer, providing superior performance in high-temperature environments and excellent resistance to petroleum-based oils, jet fuels, and most hydraulic fluids where standard Nitrile seals would fail.
- Large Diameter Sealing: With a nominal inside diameter of over 8.7 inches, this O-ring is designed to create a reliable seal on large access panels, flanges, and major system components.
- Excellent Fluid Resistance: Offers low swell and resistance to degradation when exposed to a wide array of chemicals, ensuring a durable, long-lasting seal in aggressive fluid systems.
- MS Certified Standard: As a certified MS28775 part, it guarantees that the material compound, physical properties (like durometer and compression set), and dimensional tolerances meet the highest standards for aviation safety and reliability.
- Precision Dimensions: The "-269" dash number corresponds to a specific dimensional standard (AS568), which ensures a perfect fit into large-scale glands and grooves, providing a reliable seal under system pressure.
Technical Specifications
- Standard: MS28775 / MIL-R-83248 Type I
- Full Part Number: MS28775-269
- Material: Fluorocarbon Synthetic Rubber (FKM / Viton®)
- Durometer (Hardness): 75 Shore A
- Color: Black
- AS568 Dash Size: -269
- Precise Dimensions:
- Inside Diameter (I.D.): 8.734 inches
- Outside Diameter (O.D.): 9.012 inches
- Cross Section (C.S.): 0.139 inches
- Operating Temperature Range: Approximately -15°F to 400°F (-26°C to 204°C)
- Primary Fluid Compatibility: Petroleum-based oils, fuels (Jet A, 100LL), and hydraulic fluids (MIL-H-5606, MIL-H-83282).
Aircraft Compatibility
The MS28775-269 O-ring is a standard large-diameter seal used in numerous applications across the entire spectrum of aviation, including many Textron Aviation (Cessna, Beechcraft) aircraft. Its use is determined by the specific requirements of the component it seals.
- Common Applications:
- Fuel Systems: Sealing large fuel tank access panels and major component flanges.
- Engine & Powertrain: Serving as a static case seal in large accessory gearbox housings and other firewall-forward applications that experience high operating temperatures.
- Hydraulic Systems: Utilized to seal large hydraulic reservoirs, filter housings, and accumulator end caps.
Applications
The MS28775-269 is the engineered sealing solution for large-scale joints where standard Nitrile O-rings are insufficient:
- High-Temperature Static Sealing: Its primary application is in large, stationary joints that must maintain a reliable seal at continuous operating temperatures up to 400°F.
- Aggressive Fluid Containment: Provides a durable, long-term seal in constant contact with aromatic hydrocarbons and synthetic fluids that would quickly degrade other elastomers.
Why Choose MS28775-269?
Choosing the correct O-ring material is critical for flight safety. An O-ring failure on a large access panel can lead to a catastrophic leak of fuel, oil, or hydraulic fluid. The MS28775-269, made from Fluorocarbon (FKM), is specifically designed to perform in high-temperature and chemically aggressive environments. Using a genuine, certified MS-standard part is the only way to ensure the O-ring has the correct, tested material properties and precise dimensions for the demanding conditions of flight.
Order Your MS28775-269 O-Rings Now
Ensure the integrity of your aircraft's most critical large-diameter seals with certified, high-performance O-rings. Visit Airparts.aero to order your MS28775-269 O-rings today.
The material science of the MS28775-269 O-ring sets it apart for demanding applications. Fluorocarbon (FKM) is a fluoroelastomer with a high fluorine content. The carbon-fluorine bonds in its molecular structure are extremely strong and stable, which gives the material its exceptional resistance to heat, oxidation, and chemical attack. This makes it the material of choice for sealing applications "firewall forward" and in high-performance hydraulic systems. While it does not have the extreme low-temperature flexibility of Fluorosilicone (M25988), its superior high-temperature performance and physical toughness make it the standard for a majority of high-performance fuel and oil sealing applications in aviation.
Note: This is a flight-critical sealing component. Always verify the correct O-ring part number from the applicable component maintenance manual (CMM) or aircraft Illustrated Parts Catalog (IPC). Ensure the O-ring is within its specified shelf life before installation. Lubricate with a clean, compatible system fluid to prevent damage during assembly.
