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ES49011-3 – Textron Aviation OEM Preformed Aerospace O-Ring
Available now on the Airparts.aero Marketplace.
The ES49011-3 is a high-performance, precision-molded elastomeric O-ring specifically engineered for the environmental control systems (ECS) and air conditioning architectures of Cessna, Beechcraft, and Hawker aircraft. As a member of the ES49011 series, this "-3" variant is primarily utilized as a sealing interface for R134a refrigerant systems. Its specialized chemical composition is designed to maintain a hermetic seal in the presence of polyolester (POE) lubricants and high-pressure refrigerants, preventing the "slow leaks" that often lead to cooling performance degradation in turbine and piston aircraft.
Unlike standard industrial O-rings, the ES49011-3 is manufactured to aerospace tolerances, ensuring consistent cross-sectional diameter and surface finish. This is critical for preventing "bypass leakage" in the high-vibration environment of an aircraft’s engine-driven compressor or evaporator assembly.
Key Features
Refrigerant-Grade Elastomer: Specifically formulated to resist swelling and degradation when exposed to HFC-134a (R134a) refrigerant and compatible refrigeration oils.
Superior Compression Set Resistance: Engineered to maintain its "spring-back" force over long periods, ensuring the seal remains tight through the extreme thermal cycles of flight (from cold high-altitude soak to hot tarmac operations).
Precision "Preformed" Geometry: Molded to exact specifications to prevent "twisting" during installation, a common cause of premature O-ring failure in pressurized systems.
High Shell Stability: Offers an impressive 15-year (180-month) shelf life when stored in original OEM packaging, allowing for long-term inventory stocking without the risk of "age-cracking."
Low Permeability: Designed with a high-density molecular structure that acts as a superior barrier against gas migration, critical for maintaining the charge integrity of the AC system.
Technical Specifications
Part Number: ES49011-3
Manufacturer: Textron Aviation (Cessna / Beechcraft OEM)
Component Type: Preformed Aerospace O-Ring / Gasket
Dimensions: 0.65" (L) x 0.65" (W) x 0.07" (H)
Weight: 0.01 lbs (approx. 4.5 grams)
ATA Chapter: ATA 21 (Air Conditioning / Cooling)
Certification: OEM Certificate of Conformance (CoC) provided
ECCN: 9A991.d
Aircraft Compatibility
Beechcraft King Air Series: B200, B300, 350, 350i, and 350C.
Cessna Citation Series: 525 (M2/CJ series), 560 (Encore/Ultra), and 680 (Sovereign).
Hawker Series: 400XP, 800XP, 900XP.
Note: The ES49011 series is frequently found in Keith Products and Enviro Systems air conditioning kits installed as OEM equipment on Textron airframes. Always verify the part number in your Illustrated Parts Catalog (IPC) Section 21-50 to ensure the correct size for your specific refrigerant line or evaporator port.
Applications
The ES49011-3 is utilized for Fluid Containment and Pressure Sealing. Its primary roles include:
AC Line Fittings: Sealing the high-pressure and suction-side connections of the refrigerant manifold.
Evaporator & Condenser Ports: Providing the seal at the entry/exit points of heat exchangers.
Receiver-Drier Interface: Ensuring a leak-free connection during the replacement of desiccant components.
Why Choose ES49011-3?
Choosing a genuine Textron ES49011-3 is essential for System Longevity. In aviation AC systems, "moisture" is the primary enemy. If an O-ring fails and allow even a trace amount of refrigerant to escape, it can lead to "slugging" in the compressor or the formation of acids within the system. The ES49011-3 is calibrated for a specific Durometer (Hardness) that balances ease of installation with the high-pressure containment required for Part 23 and Part 25 aircraft.
The ES49011-3 functions as a Mechanical Energized Seal. In a standard "Boss" or "Flange" fitting, the O-ring is compressed by approximately 10% to 25% of its cross-sectional diameter. The physics of the Poissons Ratio ensures that as the refrigerant pressure increases, the O-ring is physically forced against the "low-pressure" side of the groove, effectively increasing the sealing force. The use of a genuine OEM elastomer ensures that the Glass Transition Temperature ($T_g$) is low enough that the seal does not become brittle during cold-soak descents, preventing the "first-start" leaks common in systems using automotive-grade seals.
Note: This is a consumable airframe component. Always use a compatible O-ring lubricant (such as POE oil) during installation to prevent "rolling" or "scuffing" the seal. Never reuse an O-ring once the fitting has been torqued. Ensure that the seating groove is surgically clean and free of old sealant or oxidation prior to installation.
