......The end result is no one looking at that design prior to these two incidents would imagine the shaft(s) shearing and causing this problem.......
bigglesbutler- You bring up a very good point. It would not seem logical to have both the primary and backup lube pumps driven from the same gear, since this common driving gear creates a single-point-of-failure situation. But you need to understand how the accepted industry approach to system fault tolerance analysis considers such cases. For many flight critical components in the drivetrain that have no functional redundancy (such as certain gears, shafts, hubs, etc.) they are designed, analyzed, manufactured, inspected and maintained under very strict controls. Based on this approach, a catastrophic structural failure is not considered a "credible failure mode" for these components in the fault tolerance analysis. Obviously, while this approach should work well in theory, in this particular case there was a breakdown somewhere in the process.
To make a long story short, from the limited information I have seen, I do not see anything in the design of the EC 225 MRGB that would not be considered currently acceptable design practice. Could the design have been made more reliable? In hindsight, maybe so. But we can also assume that it met all regulatory safety requirements at the time the design was qualified/certified.
Here's a good description of the EC225 lube system function from an AAIB bulletin:
http://www.stepchangeinsafety.net/te...setFileID=1542