Originally Posted by
Lonewolf_50
@riff_raff What aircraft have C64 gears in them at present, that you are aware of?
Lonewolf_50-
I don't know of any MRGB designs that use C64 gears. However, the AW609 MRGB does use X-53 gears, primarily for improved loss of lube capability. The main reason that C64 is not currently used is because it was just developed a couple years ago. Bell studied upgrading existing gearboxes with C64 gears under the recent
FARDS program.
Upgrading existing MRGBs with C64 gears in certain locations where potential for scoring is high under loss of lube operation (such as spiral bevel or output stage planet meshes) would be a very cost effective approach. While the C64 (AMS 6509) raw material is currently around 2-3 times the $/lb cost of 9310 (AMS 6265), it does provide some advantages in manufacturing processing. One important advantage is that C64 is designed to use a much cleaner gas quench instead of an oil quench.