Permaswage® Aerospace Hydraulic Fittings: Complete Guide to Union, Elbow, Tee, Cross & Reducer Fittings

Permaswage® fittings are widely used throughout commercial aviation, military aircraft, helicopters, and aerospace manufacturing to create permanent, leak-free hydraulic tube connections. Designed for high-pressure fluid systems operating up to 3,000 PSI, these fittings are installed using hydraulic swaging equipment that permanently compresses the fitting onto the tubing without welding or brazing. Whether you're performing aircraft maintenance, replacing damaged hydraulic tubing, or building new fluid systems, selecting the correct Permaswage® fitting is essential for achieving a safe and reliable installation. In this guide, we'll explain the different types of Permaswage® fittings, how they are used, and provide an overview of the most common fitting series. What Are Permaswage® Fittings? Permaswage® fittings are precision-engineered aerospace hydraulic fittings that are permanently attached to tubing using a hydraulic swaging process. Rather than relying on threads, welding, or flaring alone, the fitting is radially compressed around the tube using dedicated Permaswage® tooling. This process creates a permanent, vibration-resistant, leak-free connection suitable for demanding aerospace hydraulic applications. Permaswage® fittings are commonly used in: Commercial aircraft Military aircraft Helicopters Defense systems Aerospace manufacturing Aircraft MRO facilities Government aviation programs Why Use Permaswage® Fittings? Compared to traditional tube repair methods, Permaswage® fittings offer several advantages. Benefits include: Permanent leak-free connections High vibration resistance Excellent corrosion resistance Fast aircraft hydraulic repairs Reduced aircraft downtime Elimination of welding during many repairs Field-installable using portable tooling Approved for numerous aerospace hydraulic applications Because the fittings become part of the tubing itself, they are ideal for repairing damaged hydraulic lines without replacing an entire tube assembly. Common Types of Permaswage® Fittings Permaswage® manufactures several fitting configurations designed to accommodate different aircraft hydraulic system layouts. Union Fittings Union fittings permanently connect two sections of the same size tubing. Common Part Numbers: D10036 (-06 through -16) D10136 (-20 and -24) D10339 Extended Length Union Typical applications include: Tube repairs Hydraulic line extensions Replacement of damaged tubing sections 90° Elbow Fittings Elbow fittings allow hydraulic tubing to change direction while maintaining a permanent swaged connection. Common Part Numbers: D9856 (-03 through -16) D10256 (-20 and -24) Applications include: Aircraft hydraulic routing Landing gear systems Flight control hydraulic lines Tight installation spaces Tee Fittings Tee fittings provide a three-way hydraulic connection for branching fluid lines. Common Part Numbers: D9855 (-03 through -16) D10255 (-20 and -24) Typical applications: Hydraulic distribution Branch circuits Aircraft manifold systems Cross Fittings Cross fittings provide four-way hydraulic connections where multiple fluid lines intersect. Common Part Numbers: D9854 (-03 through -16) D10254 (-20 and -24) Applications include: Hydraulic manifolds Complex aircraft plumbing Multi-line hydraulic distribution Union Reducer Fittings Union reducers permanently connect two different tubing sizes. Common Part Numbers: D10045 Series Example configurations include: D10045D0604 D10045D0806 D10045D1008 D10045D1208 These fittings simplify hydraulic repairs where tube diameters change. Elbow Reducer Fittings Elbow reducers combine a 90-degree direction change with a tube size reduction. Common Part Numbers: D10035 Series Tee Reducer Fittings Tee reducers provide a branch connection while reducing one outlet size. Common Part Numbers: D10023 Series Cross Reducer Fittings Cross reducers allow multiple hydraulic tube sizes to intersect in one fitting. Common Part Numbers: D10033 Series Other Common Permaswage® Tube End Components Several additional components are commonly used alongside Permaswage® fittings. Flared Tube Components D10006 Coupling Nuts D10010 Flared Sleeves Used to repair damaged flared tube ends. Flareless Tube Components D10006 Coupling Nuts D10007 Flareless Sleeves Used for flareless tube repair applications. Lipseal Fittings Male Lipseal D11007 Series Female Lipseal DD00200A Series Female Lipseal Reducers DD00300A Series These fittings are commonly used during aircraft hydraulic tube-end repairs. How Permaswage® Fittings Are Installed A successful installation begins with proper tube preparation. The typical installation process includes: Cut the tubing using a Permaswage® Chipless Cutter. Deburr the tube using a Permaswage® Deburring Tool. Mark the insertion depth using a Permaswage® Marking Tool. Install the fitting onto the tubing. Position the proper swage dies and swage head. Swage the fitting using a hydraulic power unit. Verify the completed installation using a Permaswage® Inspection Gage. Each step is critical for producing a reliable, leak-free hydraulic connection. Permaswage® Tooling Required Installing Permaswage® fittings typically requires: Swage Heads Swage Dies Hydraulic Power Units Inspection Gages Marking Tools Deburring Tools Chipless Cutters Field Repair Kits Using the correct tooling ensures proper fitting compression and installation quality. Industries That Use Permaswage® Fittings Permaswage® fittings are trusted throughout: Commercial aviation Military aviation Aerospace manufacturing Helicopter maintenance Aircraft MRO facilities Defense contractors Government aviation agencies Their proven reliability has made them a standard solution for permanent aircraft hydraulic tube repairs. Commonly Requested Permaswage® Fitting Part Numbers Union Fittings D10036 D10136 D10339 Elbow Fittings D9856 D10256 Tee Fittings D9855 D10255 Cross Fittings D9854 D10254 Union Reducers D10045 Elbow Reducers D10035 Tee Reducers D10023 Cross Reducers D10033 Flared Tube Components D10006 D10010 Flareless Tube Components D10007 Lipseal Fittings D11007 DD00200A DD00300A Why Buy Permaswage® Fittings from Top Flight Tools? At Top Flight Tools, we specialize in sourcing factory new, new surplus, and inspected aerospace hydraulic tooling and fittings. We help customers locate: Union Fittings Elbow Fittings Tee Fittings Cross Fittings Reducer Fittings Lipseal Fittings Flared Sleeves Flareless Sleeves Coupling Nuts Swage Heads Swage Dies Power Units Inspection Gages Marking Tools Deburring Tools Chipless Cutters Field Repair Kits Whether you're replacing a single fitting or assembling a complete hydraulic repair kit, our team can help identify the correct components for your application. Conclusion Permaswage® fittings have become the industry standard for permanent aerospace hydraulic tube repairs. With a complete range of union, elbow, tee, cross, reducer, flared, flareless, and lipseal fittings, the system provides reliable, leak-free connections for some of the world's most demanding aircraft hydraulic systems. Selecting the correct fitting—and installing it using the proper Permaswage® tooling—is essential for achieving long-lasting hydraulic system performance and minimizing aircraft downtime. ⚠️ Disclaimer Top Flight Tools (TFT) is an independent reseller and is not affiliated with, sponsored by, or endorsed by Permaswage® or Precision Castparts Corp. (PCC). All product names, trademarks, and registered trademarks are the property of their respective owners. Any reference to Permaswage® products, specifications, or part numbers is provided for informational purposes only. All Permaswage® trademarks and part numbers remain the property of their respective companies. While every effort is made to ensure the accuracy of the information provided, it is the customer's responsibility to verify all specifications, compatibility, and suitability of products for their intended application prior to use. TFT assumes no liability for errors, omissions, or the misuse or misapplication of this information, and disclaims any responsibility for damages resulting from reliance upon it.