LW14820 - Lycoming Internal Retaining Ring

LW-14820 – Lycoming™ Piston Pin Internal Retaining Ring

Available now on the Airparts.aero Marketplace.

The Lycoming LW-14820 is a flight-critical, genuine OEM internal retaining ring, also known as a circlip. Its indispensable function is to securely lock the piston pin (wrist pin) within the piston, preventing any lateral movement. This small, precision-engineered spring steel component is fundamental to the integrity of the entire piston and connecting rod assembly. It ensures that the hardened steel piston pin remains perfectly centered, preventing it from drifting sideways and causing catastrophic scoring and damage to the cylinder wall.

Manufactured from high-yield-strength spring steel and heat-treated to exacting specifications, the LW-14820 is designed to be compressed for installation and then expand with significant force into its machined groove inside the piston. This outward radial force locks it into place, withstanding the high inertial loads generated by the reciprocating motion of the piston. Given its critical role and low cost, it is a mandatory single-use replacement part.

Key Features

• Genuine Lycoming OEM Part: The only component guaranteed to meet the precise material, temper, and dimensional specifications required for this high-stress application.

• High-Strength Spring Steel Construction: Fabricated from a heat-treated, high-carbon spring steel alloy to provide the required clamping force and fatigue resistance.

• Prevents Catastrophic Cylinder Damage: Positively locks the piston pin, preventing it from contacting and destroying the cylinder wall, which would lead to an immediate in-flight engine failure.

• Precision Stamped for Secure Seating: The ring's square-edged cross-section is designed to seat perfectly in its groove, providing maximum resistance against thrust loads from the piston pin.

• Single-Use Component for Maximum Reliability: Engineered to be replaced every time a piston pin is installed to eliminate the risk of failure from material fatigue or lost tension.

Technical Specifications

• Part Number: LW-14820

• Component Type: Internal Retaining Ring / Circlip / Piston Pin Lock

• OEM Manufacturer: Lycoming Engines

• Material: Heat-Treated High-Carbon Spring Steel

• Finish: Phosphate and Oil or similar corrosion-resistant finish.

• Application: Piston pin retention for nearly all Lycoming engine pistons. Two are required per piston assembly.

Engine Compatibility

The LW-14820 retaining ring is one of the most universal parts in the Lycoming engine ecosystem, specified for nearly all direct-drive Lycoming engine families, including but not limited to:

• O-235, O-320, IO-320, AEIO-320 Series

• O-360, IO-360, AEIO-360, TIO-360 Series

• O-540, IO-540, AEIO-540, TIO-540, LTIO-540 Series

• IO-580 Series

• IO-720 Series

Crucial Note: The specific engine model and serial number must be checked against the latest revision of the official Lycoming Parts Catalog to ensure correct part number applicability. The engine parts catalog is the final authority.

Applications

This retaining ring is a mandatory replacement part during any maintenance that requires the removal of a piston pin. This includes:

• Complete Engine Overhaul

• Top Overhaul or Single Cylinder Replacement

• Piston and/or Connecting Rod Replacement

Why Choose LW-14820?

Choosing a genuine Lycoming LW-14820 is an absolute necessity for flight safety. The failure of this single, inexpensive component will lead directly to the destruction of a cylinder assembly worth thousands of dollars and will result in an in-flight engine failure. Re-using an old ring is exceptionally dangerous, as the stress of a single installation and removal cycle can cause unseen fatigue or a loss of the critical spring tension required to hold it in place. Using a non-genuine part introduces the risk of improper material, faulty heat treatment, or incorrect dimensions, any of which could cause the ring to fail under load. For this critical application, there is no substitute for the guaranteed quality of a genuine Lycoming part.

The Lycoming LW-14820 functions as a precisely engineered spring, designed to operate within its material's elastic range during installation. It is manufactured from a high-yield-strength spring steel, which is quenched and tempered to create a tough, martensitic microstructure. This allows the ring to be elastically deformed (compressed) to fit through the piston pin bore and then spring back to its original diameter with a calculated amount of outward radial force. This force is what presses the ring securely into its machined groove. The ring's design features a sharp, square-edged profile on the side that faces the piston pin. This is a critical engineering feature designed to resist axial thrust. When the piston pin attempts to move sideways and pushes against the ring, the sharp edge presents a 90-degree face to the square wall of the groove, maximizing resistance and preventing the ring from being dislodged or "ramped" out of its seat—a failure mode that could occur with a rounded-edge design.

Note: This is a flight-critical, single-use component. This retaining ring MUST be replaced with a new one every time a piston pin is installed. Re-using a ring can lead to loss of tension or fatigue failure, resulting in catastrophic engine damage. Pay strict attention to the installation orientation as specified in the overhaul manual; the sharp edge must face away from the piston pin. Installation must be performed by a certified A&P mechanic in strict accordance with the applicable Lycoming overhaul manual.

Documentation

The definitive part number applicability and installation procedures are detailed in the applicable Lycoming engine maintenance, overhaul, and parts catalogs for the specific engine model.