Manufacturing Super Stinson L-5 Engine Mounts: From CAD Model to Finished Structure

The Stinson L-5 is one of the most iconic liaison aircraft ever built. Originally developed during World War II, it remains a highly appreciated aircraft among restorers and vintage aircraft operators around the world.

When original structural components become unavailable, maintaining these aircraft often requires a careful combination of engineering, manufacturing expertise and respect for the original design intent.

Recently, AvioUniversal completed the production of a small batch of engine mounts for the Super Stinson L-5, using aeronautical-grade materials and production techniques.

Understanding the Original Design

The engine mount is a primary structural component responsible for transferring engine loads into the aircraft fuselage.

Any replacement component must therefore reproduce:

• Original geometry

• Attachment point locations

• Structural load paths

• Material characteristics

• Welding quality requirements

The project started with the reconstruction and verification of the original geometry using original manufacturing documentation, subsequently transferred into a modern CAD environment.

3D CAD model used during production planning.

Manufacturing Process

The structure was manufactured using normalized AISI 4130 steel tubing, a material widely used in aeronautical welded structures due to its combination of strength, weldability and fatigue resistance.

The manufacturing process included:

• Tube preparation and profiling

• Precision assembly on dedicated jigs

• TIG welding of all structural joints

• Dimensional verification throughout production

• Local stress-relief heat treatment of critical nodes

• Final inspection before surface finishing

Particular attention was dedicated to maintaining geometric accuracy and minimizing welding distortion throughout the assembly process.

Assembly and welding operations during production.

Heat Treatment of Critical Nodes

Certain structural nodes received localized heat treatment as part of the manufacturing process. This operation is performed under controlled conditions and forms part of AvioUniversal's established production practices for welded steel tube structures.

Quality Control and Traceability

Each manufactured assembly receives its own identification plate containing:

• Part Number

• Serial Number

• Aircraft model reference

• Production date

This allows complete traceability of the manufactured component throughout its service life.

Identification plate installed on the finished structure.

Weld Verification

One of the most critical aspects of any welded aeronautical structure is the quality of the weld itself.

To verify the effectiveness of the welding process, representative test specimens were produced using the same materials and joint preparation methods adopted for the final structure.

Representative welded specimen after sectioning and inspection.

Surface Finishing

After completion of manufacturing and inspection activities, the structures received protective surface treatment and final finishing.

The finished structures received a protective coating in AvioUniversal Blue, our corporate color and a recognizable hallmark of AvioUniversal products. The coating provides corrosion protection while giving each component a distinctive visual identity.

Delivering More Than a Component

For this project, AvioUniversal delivered not only the finished engine mount assemblies but also a dedicated production and conformity report documenting:

• Manufacturing activities

• Material traceability

• Quality inspections

• Weld verification procedures

• Component identification

This approach provides owners and restorers with additional confidence regarding the origin and manufacturing quality of the supplied component.

Supporting Vintage Aircraft Preservation

Projects such as the Super Stinson L-5 engine mount demonstrate how modern engineering and manufacturing capabilities can support the preservation of historic aircraft while maintaining high standards of workmanship and traceability.

At AvioUniversal, we believe that preserving aviation heritage requires more than reproducing parts—it requires understanding how those parts were originally designed, built and used.

Need a welded steel tube aeronautical structure reproduced?

Whether you need a replacement engine mount, fuselage structure, landing gear component or a custom welded assembly, our team can support the entire process from engineering and manufacturing to final delivery.

📧 info@aviouniversal.com🌐 www.aviouniversal.com