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AN817-8D – Eaton Aeroquip Aerospace 90 Degree Fitting
Available now on the Airparts.aero Marketplace.
Overview
The AN817-8D is a military-standard 90-degree elbow coupling nut, a specialized and essential component for creating tight, right-angle connections in aerospace fluid systems. Also known by its Eaton Aeroquip part number 8891-8D and the superseding military specification M83798/3-8, this is not a standard fitting. It is an integrated "elbow B-nut" designed to be used with a tube sleeve (AN819) to connect a 1/2-inch flared tube directly to a male AN fitting at a 90-degree angle. Machined from high-strength aluminum alloy, this fitting is a critical problem-solver for routing fuel, oil, and hydraulic lines in the confined spaces of an airframe.
Key Features
- Integral 90-Degree Bend: Combines the function of a coupling nut and a 90-degree elbow into a single component. This allows for a very tight-radius turn directly at the connection point, which is impossible to achieve by bending rigid tubing.
- Creates High-Pressure Flare Seal: When tightened, it applies the necessary clamping force to seal a flared tube and sleeve against a male 37-degree flare fitting. This creates a proven, highly reliable metal-to-metal seal capable of withstanding high pressures and intense vibration.
- Lightweight Aluminum Alloy: The "D" suffix specifies that the nut is machined from a solid piece of high-strength 2024-T851 aluminum alloy. This material provides an excellent combination of strength and light weight.
- AN Standard Certified: As a certified Air Force/Navy (AN) standard part, it guarantees perfect interchangeability with any other standard AN/MS/AS fitting of the same size, ensuring dimensional accuracy, thread quality, and material integrity.
- Blue Anodized Finish: Finished with a blue anodized coating per MIL-A-8625. This finish not only provides enhanced corrosion and wear resistance but also serves as the standard color code, immediately identifying the fitting as being made from aluminum alloy.
Technical Specifications
- Standard: AN817 (Nut, Coupling, Elbow, Flared Tube, 90 Degree)
- Full Part Number: AN817-8D
- Eaton Aeroquip P/N: 8891-8D
- Superseding P/N: M83798/3-8
- Component Type: 90 Degree Elbow Coupling Nut ("Elbow B-Nut")
- Material (D): 2024-T851 Aluminum Alloy
- Finish: Blue Anodized
- Tube Size (Dash Size): -8 (for 1/2 inch Outside Diameter tubing)
- Thread Specification: 3/4-16 UNF-3B
Aircraft Compatibility
The AN817-8D is a universal fluid fitting used on nearly every type of certified and experimental aircraft where a 90-degree connection for a 1/2-inch fluid line is required in a space-constrained area.
- Common System Applications:
- Engine Compartments: Connecting fuel and oil lines to the firewall, engine accessories, and oil coolers where space is minimal.
- Hydraulic Systems: Routing hydraulic lines around structural members to connect to landing gear actuators, brake calipers, and flap motors.
- Airframe Plumbing: Used anywhere a tight, right-angle turn is needed for fuel, hydraulic, or pneumatic plumbing.
Applications
The AN817-8D is the industry-standard component for creating a serviceable, 90-degree flared tube connection:
- Space-Constrained Plumbing: The primary solution for making a right-angle connection without the risk of kinking or over-stressing a bent tube.
- Hose and Tube Assembly: Used to connect both rigid flared tubing and flexible hose assemblies to other components at a 90-degree angle.
Why Choose AN817-8D?
In complex aircraft systems, proper routing of fluid lines is critical to prevent chafing and vibration-induced failures. The AN817-8D provides a certified, engineered solution for making tight 90-degree turns. Using a genuine AN-standard fitting guarantees that it has the correct material strength, precise threads, and dimensional tolerances to create a dependable, high-pressure seal. For any airworthy installation, especially in tight quarters, trust only certified AN/MS hardware.
Order Your AN817-8D Fittings Now
Solve your complex plumbing challenges with certified AN-standard hardware. Visit Airparts.aero to order your AN817-8D 90-degree elbow coupling nuts today.
The AN817-8D elbow nut is a critical problem-solver in fluid system design. Standard practice dictates that rigid tubing must be bent with a specific minimum bend radius to avoid weakening or collapsing the tube. In many areas of an aircraft, there is insufficient physical space to accommodate such a large bend radius. The AN817-8D eliminates this problem by incorporating the 90-degree turn into the nut itself. This allows a straight piece of tubing to be connected directly to a male fitting that is parallel to it, achieving a 90-degree change in fluid direction in the smallest possible physical space. This preserves the full strength of the tubing and simplifies complex plumbing installations.
Note: Installation must be performed by a certified A&P mechanic. The flared tube end should never have sealant applied. The B-nut threads should be lightly lubricated with the system fluid before tightening. The nut must be tightened to the specified torque value using a calibrated torque wrench to achieve a proper seal.
