OH-58 MRGB composite spiral bevel gear

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This example shows how to make light weight composite gears for helicopter transmissions. Main Rotor Gear Box (MRGB) designed for US Army under SBIR proposal. https://www.sbir.gov/node/1654343In addition to weight saving it is expected to have cost saving because metal components can be made out of smaller forgings. The composite rim is rendered as carbon fiber Twill cloth for decoration only. The real composite structure is filament wound around multiple design elements on the back of the rim and on the end of the hub. As you can see on the original MRGB drawing the spiral bevel gear is assembled out of two parts. The reason for two parts is because it is impossible to machine Gleason spiral bevel teeth - not enough space for Gleason face cutter(it would hit the hub). Indeed today, this gear can be machined on a CNC with a ball-end tool as a single part. But US Army under direction of NASA Gear Research Center found it to be more beneficial to develop a composite design. MRGBs of modern helicopters are kind of similar in concepts with a large spiral bevel gear set as a focal point. Check this EU helicopter gear video: https://www.youtube.com/watch?v=oD4jKBOIBwcto get an idea about complexity of helicopter gear manufacturing. Similar spiral bevel gears are on Boeing CH-47. It means that MRGB designers have been liking to have a spiral bevel ring gear sitting on a long hub for over 50 years already and now they are trying to find a better way to design and make them.