In the highly demanding world of aerospace, excellence is non-negotiable. Every component, from engines to O-rings, must perform flawlessly, as lives depend on their reliability. With stringent requirements such as being listed on the Qualified Products List (QPL) and meeting various certifications, only a few suppliers can meet these extreme demands. Recently, several manufacturers have exited this space for several reasons, leading to a dwindling number of suppliers for these applications. Fortunately, Zatkoff Seals & Packings is a Freudenberg-NOK Preferred Distributor, offering exceptional products for the aerospace industry. Our friends at Freudenberg-NOK take the responsibility for safety and quality extremely seriously, implementing extensive quality control measures.
What Makes the Aerospace Industry Challenging for Seals?
Beyond the obvious safety concerns, aerospace applications pose daunting challenges for seals. One unique challenge is extreme pressure changes, as seals can experience vastly different pressures on the ground, during take-off, landing, or even during flight as altitude changes. With ever-changing weather at ground level and altitude, conditions such as temperature, ozone, and moisture can vary drastically. Additionally, seals face significant mechanical stresses, including vibrations and shocks during operation. Finally, seals are exposed to various fluids, such as hydraulic fluids, which require a sealing material to be chemically compatible. In addition to all this stress, aerospace is highly regulated with specific and strict guidelines, requiring specialized materials and expertise to ensure safety and compliance.
Freudenberg N888 O-rings for Aerospace
One specialized material that meets these extreme conditions is Freudenberg N888, manufactured at their O-ring facility in Santa Ana, California. N888 is a specialized NBR (nitrile butadiene rubber) compound developed by Freudenberg-NOK Sealing Technologies specifically for the aerospace industry. This material can be utilized in a diverse range of aerospace applications, including hydrocarbon fluid-based hydraulics such as landing gear, flight control systems, wing flaps, cargo doors, braking systems, and emergency systems. Other applications include shock absorbers, struts, and non-aircraft applications like maintenance or ground equipment that also require specialized certifications.
Freudenberg N888 is on the Qualified Products List (QPL) and has numerous certifications. It is typically suited for service temperatures ranging from -65°F to +250°F (-54°C to +121°C). This material is also certified and resistant to petroleum-based hydraulic fluids, red hydraulic fluids, mineral-based oil, and fire-resistant synthetic hydrocarbon fluids, including low-temperature variants. One certification requires the NBR O-ring to perform in these fluids for a specified period at +250°F (+121°C).
N888 meets the current specification for a grade of hydraulic oil used in aircraft and the standard for preformed hydraulic packing with an O-ring, ensuring it can withstand temperatures up to +275°F (+135°C). Additionally, the material meets several specifications that provide design criteria and related features used in hydraulic equipment. It fulfills the design and installation requirements for hydraulic systems in aircraft and has been assigned a standard part number for O-rings used in static sealing in various aircraft components.
The N888 O-rings boast a shore hardness of 73, placing them in the moderately hard range on the 0 to 100 scale. These O-rings are impressively durable, with a tensile strength of 2,049 psi (14.13 MPa) as per ASTM D1414 standard testing. They excel in flexibility too, stretching up to 318% of their original length before breaking. Additionally, their modulus at 100% elongation is 558 psi, indicating strong resistance to extrusion. Please note this information is considered typical values and can vary depending on conditions or between tests as elongation tests are conducted to failure which can cause variation in each test.
Expertise That Matters
With decades of experience and a highly trained team, our sealing experts at Zatkoff are here to ensure you have the right seal for optimal operation, safety, and regulatory compliance. As a Freudenberg-NOK Preferred Distributor, you also have access to their global network of experts, ensuring every detail is accounted for. One notable example of this partnership is our recent delivery of N888 O-rings for a customer's equipment used in aircraft maintenance. Often, simple ground equipment like this is overlooked, but our team's expertise ensured we provided a solution that not only performs well but also meets all regulatory requirements, preparing them for any inspections.
Do you think Freudenberg N888 O-rings could be the right solution for your aerospace application? Contact our experts today to ensure your equipment is safe and fully optimized.