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AN777-5D – Aluminum Fluid Connector 75 Degree for P-51 Mustang
Available now on the Airparts.aero Marketplace.
Overview
The AN777-5D is a military-standard, 75-degree elbow, a specialized "bite-type" flareless tube fitting engineered for use in the high-pressure fluid systems of classic and legacy aircraft like the North American P-51 Mustang. This is not a standard flared fitting; the AN777 is designed to connect a piece of un-flared rigid tubing to another component with a standard male AN 37-degree flare. Machined from high-strength aluminum alloy, this fitting provides a robust, leak-proof, 75-degree connection, essential for navigating the complex plumbing within a high-performance vintage aircraft.
Key Features
- Flareless "Bite-Type" Seal: The key feature is the flareless connection. This design uses a ferrule or "sleeve" that, when compressed by the nut, bites into the outer surface of the rigid tubing, creating a positive, high-pressure seal without the need for a specialized flaring tool.
- Dual-Interface Design: Provides a highly reliable transition between a flareless MS-style tube connection and a standard male AN 37-degree flared end. This allows for the integration of rigid tube runs with flexible hose assemblies.
- Lightweight Aluminum Alloy: The "D" suffix specifies that the fitting is machined from a solid piece of high-strength 2024-T351 aluminum alloy. This material provides an excellent combination of strength and light weight, which was critical in the design of high-performance fighter aircraft.
- 75-Degree Angled Body: The elbow is formed at a 75-degree angle, providing a specific, non-standard routing option for plumbing in tight and complex installations where a 45 or 90-degree elbow would not fit correctly.
- AN Standard Certified: As a certified Air Force/Navy (AN) standard part, it guarantees the correct dimensions, material composition, and performance characteristics required for an airworthy restoration or repair of a historic aircraft.
Technical Specifications
- Standard: AN777 (Elbow, Flareless Tube, 75 Degree)
- Full Part Number: AN777-5D
- Component Type: 75° Flareless "Bite-Type" Tube to Male AN Flare Elbow
- Material (D): 2024-T351 Aluminum Alloy
- Finish: Blue Anodized
- Flareless Tube End:
- Tube Size (Dash Size): -5 (for 5/16 inch O.D. rigid tubing)
- Flared End:
- Fitting Size: -5 AN Male
- Flare Angle: 37°
- Thread Specification: 1/2-20 UNF
Aircraft Compatibility
The AN777-5D and other flareless fittings are standard components on many World War II and Korean War era military aircraft, including the iconic P-51 Mustang.
- Primary Aircraft Platform:
- North American P-51 Mustang
- Common System Applications:
- Hydraulic Systems: Used for connecting rigid hydraulic lines for landing gear, flaps, and gun charging systems.
- Fuel & Oil Systems: Connecting rigid plumbing for fuel and oil lines throughout the engine compartment and airframe.
- Coolant Systems: Used in the extensive plumbing of the Mustang's liquid-cooled Merlin engine.
Applications
The AN777-5D is a critical component for authentic aircraft restoration and maintenance:
- Vintage Aircraft Plumbing: The specified fitting for creating a robust, high-pressure, 75-degree turn in a rigid fluid line.
- Authentic Restoration: Essential for restorers seeking to use the original, factory-specified type of hardware to maintain the historical accuracy and certified performance of the aircraft.
Why Choose AN777-5D?
In a high-performance aircraft like the P-51 Mustang, where fluid systems operate at high pressures and are subjected to extreme vibration and G-forces, the integrity of every fitting is paramount. The AN777 flareless fitting was an advanced technology for its time, providing a reliable seal on rigid tubing without the risk of a cracked flare. Using a genuine, certified AN777-5D is the only way to ensure the fitting has the correct material strength and precise dimensions required by the original engineering drawings. For an authentic and airworthy restoration, there is no substitute.
Order Your AN777-5D Fittings Now
Ensure the authenticity and integrity of your vintage aircraft's fluid systems with certified, original-specification hardware. Visit Airparts.aero to order your AN777-5D flareless fittings today.
The AN777-5D flareless fitting creates a seal through the controlled deformation of a separate component—the MS-standard sleeve or ferrule. The rigid tube is inserted into the fitting body until it bottoms out. A sleeve and a nut are then slid over the tube. As the nut is tightened to a specific torque, it drives the tapered sleeve forward into the fitting body. This action causes the hardened leading edge of the sleeve to "bite" into the outer surface of the tubing, displacing a small ridge of metal. This bite creates the primary, high-pressure seal, while the rear of the sleeve simultaneously clamps down on the tube, providing vibration damping and support. This design was often preferred for high-pressure steel hydraulic lines where creating a perfect 37-degree flare was difficult in the field.
Note: This is a flight-critical fluid system component. Installation must be performed by a certified A&P mechanic with experience in vintage aircraft systems. The tube end must be perfectly square, clean, and free of burrs. The nut must be torqued to the value specified in the aircraft's original maintenance manuals to ensure the sleeve bites correctly without over-stressing the tube. These fittings are not intended for use with flexible hoses.
