you did not say where the part is failing. Are the blades coming off the hub? I would have added a fillet where the blade meets the hub to make that area much thicker. 3d printing and parts that taper are not the greatest do the the printing by layer.. so you unfortunately need to use very thin layers to get the tapered area as smooth as possible. The issue with that is you add more places to delaminate. Would it not have been possible to fabricate a mount directly behind the crank shaft to mount an electric fan to provide cooling? How big is that fan? Looks like only a few inches across.. something like a 120mm AC Rack cooling fan.. something like this https://www.amazon.com/SXDOOL-Coolin...f&gad_source=1