MS20822-4 – Lycoming Engines OEM 90 Degree Elbow .250 Tube .125
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Overview
The MS20822-4 is a military-standard 90-degree elbow fitting, an essential and widely used component in the assembly and installation of Lycoming aircraft engines. This fitting is engineered to adapt a standard AN 37-degree flared tube connection to a male NPT (National Pipe Taper) thread. It allows a 1/4-inch fluid line to be connected at a right angle to a threaded port on an engine component, such as a fuel pump, oil cooler, or instrument transducer. As a part specified by Lycoming for use on their engines, it is manufactured to exacting military standards to ensure a reliable, leak-proof, high-pressure connection in the demanding firewall-forward environment.
Key Features
- Dual-Interface Design: Provides a highly reliable transition between two distinct sealing methods: the AN 37-degree flare for tubing and the NPT taper for threaded ports on engine accessories.
- AN 37-Degree Flare Seal: The flared end is machined with a precision 37° seating surface. This is the universal standard for aerospace fluid fittings, creating a highly reliable metal-to-metal seal when connected with a flared tube, sleeve, and B-nut.
- Tapered Pipe Thread Seal: The NPT threaded end is tapered, creating a seal through the principle of thread deformation when tightened into a female port. This interference fit provides a strong mechanical joint and a fluid-tight seal.
- High-Quality Material: Typically machined from high-strength aluminum alloy (designated with a "D" suffix, e.g., MS20822-4D) for lightweight applications or steel (designated with a "J" suffix) for high-pressure or high-strength requirements on the engine.
- MS Certified Standard: As a certified Military Standard part, it guarantees precise dimensional tolerances, thread quality, and material integrity. It is the superseding part for the legacy AN822-4 fitting, ensuring full interchangeability.
Technical Specifications
- Standard: MS20822 (Elbow, Tube To Pipe, 90 Degree)
- Full Part Number: MS20822-4 (Material suffix, e.g., "D" for aluminum, is often required)
- Legacy Part Number: AN822-4
- Component Type: 90° Flared Tube to Male Pipe Thread Elbow
- Flared Tube End:
- Tube Size (Dash Size): -4 (for 1/4 inch O.D. tubing)
- Flare Angle: 37°
- Thread Specification: 7/16-20 UNF
- Pipe Thread End:
- Nominal Size: 1/8 inch
- Thread Standard: NPT (National Pipe Taper)
Aircraft Compatibility
The MS20822-4 is a universal fluid fitting used on nearly every Lycoming engine installation across the general aviation fleet. Its use is determined by the specific plumbing requirements of the engine model and airframe installation.
- Common Engine Series:
- O-235, O-320, IO-320
- O-360, IO-360, AIO-360, AEIO-360
- O-540, IO-540, TIO-540, AEIO-540
- IO-720
- Common System Applications:
- Fuel Systems: Connecting fuel lines from the airframe to the engine-driven fuel pump or from the fuel servo to the flow divider.
- Oil Systems: Routing oil lines to and from coolers, and for connecting oil pressure sensors.
- Primer Systems: Connecting the primer lines to the cylinder intake ports.
Applications
The MS20822-4 is the industry-standard solution for making a right-angle fluid connection on an engine:
- Engine Accessory Connection: Allows a fluid line to be connected to an engine accessory port in a tight space where a straight fitting would interfere with other components.
- Firewall Forward Plumbing: Facilitates the clean and efficient routing of tubing around the engine and within the engine compartment.
Why Choose MS20822-4?
In engine fluid systems, where leaks can lead to in-flight engine failure or fire, the integrity of every fitting is paramount. The MS20822-4 is manufactured and certified to a military standard, guaranteeing that it has the correct material strength, precise flare angle, and thread tolerances to create a dependable, high-pressure seal in the high-vibration, high-temperature engine environment. Using non-certified, commercial-grade fittings can introduce parts with incorrect flare angles or poor thread quality, leading to leaks and potential engine failure. For any airworthy engine installation, trust only certified AN/MS hardware.
Order Your MS20822-4 Fittings Now
Ensure the integrity of your Lycoming engine's critical fluid systems with certified MS-standard hardware. Visit Airparts.aero to order your MS20822-4 90-degree elbow fittings today.
The MS20822-4 fitting masterfully combines two different sealing technologies for use on an engine. The AN flare end utilizes a mechanical seal. The 37-degree cone on the fitting provides a surface against which a flared tube is clamped by a B-nut, creating a metal-to-metal seal that is highly resistant to vibration and can be reconnected multiple times. The NPT (National Pipe Taper) end, conversely, creates a seal through a principle called "thread interference." Both the male threads on the fitting and the female threads in the engine component port are tapered. As the fitting is tightened, the threads are wedged together, creating a seal through the deformation of the threads themselves. This is why a thread sealant (like Titeseal or Loctite 567) is required on NPT threads to fill any microscopic voids and ensure a perfect, leak-proof seal against high-pressure engine fluids.
Note: Installation must be performed by a certified A&P mechanic. The flared tube end should never have sealant applied. The NPT end requires an appropriate, fuel/oil-resistant thread sealant. Support the fitting with a wrench during tightening to prevent stress on the engine component it is threaded into. Do not overtighten NPT fittings, as this can crack the port casting.
