Yes. Right on! I vote for a new shaft without any weld, except that it would take years to certify.
Colibri49-
While EC apparently seems comfortable with EB/laser welding finished gear shafts, I know that other transmission OEMs prefer not to use this approach. The problem is that since the weld is performed after heat treatment of the gear, the metallurgical properties in the weld HAZ (heat affected zone) will remain in the as-welded condition, which is not optimum. The weld HAZ cannot be improved even with a thermal stress relief and normalization cycle.
If the reports of weld failures are true, even if EC retains the welded shaft design (with any necessary design changes) then there will still be a lengthy re-qualification process. Since the gear shaft is a flight critical component, the weld process itself and any post weld QA procedures (such as NDI, etc.) must also be re-qualified.
I appreciate why EC chose to use a welded bevel gear shaft design. And that is because it is definitely lighter than the conventional 2-piece mechanically fastened design approach, as well as being less expensive. However, there is a very good reason many OEMs still use the 2-piece design, and that is because it is very difficult in a production environment to ensure the extremely high quality levels needed in the welds.
Here is a link to a drawing of an
older MGB design (I believe it's a Huey MGB) that has a similar layout to the EC225, with a spiral bevel input gear stage. You can see how the spiral bevel gear is mechanically fastened to the shaft. While it may seem counter-intuitive, from an overall fault-tolerance standpoint this design is actually better than the EB/laser welded design. Since it is an easier QA task to verify the correct installation of fasteners than it is to verify the integrity of an EB/laser weld joint.
Very interesting discussion! I've even learned a few new things.