Reverse Engineering of a Bell-206 Tail Rotor Gearbox Jean-Philippe Roy

Designing Bell-206 GearBox Introduction ÉNA Aircraft Maintenance students needed a gearbox they could assemble and disassemble many times to practice their mechanical skills without having to work on expensive certified Bell Helicopter parts. 2

Designing Bell-206 GearBox Introduction Our gearbox had to be almost identical to the original Bell design. Although, it had to be designed using standard parts to reduce its cost. After drawing some sketches, we realized that CATIA V5 workbenches would greatly facilitate our project in terms of visualization, conception and production. Not to mention it is all achieved within one program. 3

Designing Bell-206 GearBox Approach Start with Standard Functional Calculations Avoid Assembly Interference Manufacturing Planning Results 4

We first used the maintenance manual to define the main dimensions and figure out the gearbox size and required dimensions. Then we exported them on Part design sketches to get a 3D visual understanding. This allowed us to make decisions on functional part tolerances and datums. Designing Bell-206 GearBox Start with Standard 5

Standard elements were imported from online suppliers catalog as Step files into the Assembly design workbench. This is how we respected standards parts dimensions and tolerance. 6

Designing Bell-206 GearBox Functional Calculation The calculations of functional dimensions and tolerance were clearly presented using CATIA V5R20 Drafting workbench. 7 Final part definitions and clearances were defined from standard part sizing and functional surfaces.

Designing Bell-206 GearBox Avoid Assembly Interferences The Assembly Design workbench helped including standard elements and define dimensions, tolerances, gaps and shims definition using CATIA measuring tools. 8

Designing Bell-206 GearBox Planning the Casting Molded Part analysis on the 3D model helped us thinking about a casting solution for the gearbox itself. Multilevel sand casting using a 3D printed model as original shape was the less expensive solution according to the school available means. 9

Designing Bell-206 GearBox Planning the Casting We used CATIA to plan the machining of molded parts using 6 target points (datums) for isostatics. 10

Designing Bell-206 GearBox Manufacturing We also used CATIA to generate the G-code used for the CNC machine tools, providing efficiency and a good precision for a small production lot size. 11

Designing Bell-206 GearBox Results Even though the project is not completed, the results are good and everything is doing well. CATIA really helped towards all the development of the reduction gear box with its multiple functions. It allowed me to create an entire assembly, define multiple components with detail drawings and finally to plan the production of the gearbox. Some big steps are still to come and we hope that CATIA V5R20 will help resolving a lot of them. 12

Designing Bell-206 GearBox In conclusion CATIA Modeling, Drafting and Planning workbenches give an accurate and reliable design when it comes to do general reverse engineering. Without Dassault System products, this project wouldn't have been possible. 13