I note with the continuing discussion that there are at least two different problems. One was transmission cases that cracked with a subsequent loss of oil and the other was the oil pumps and the vespel splines.
The transmission itself is just that, a bunch of gears that spin around and get oil sprayed on them with the oil going to an external oil cooler. That's a pretty common concept. This really seems more of a manufacturing problem than a design flaw. Making cases and pumps and splines that last should fix the problems.
A few years back, there were a couple of main rotor masts in the 76 that were found to be cracked, one almost half way round. Turned out to be a bad manufacturing batch. Kind of like the any MGB, the mast is what NASA would call a "criticality one" component.
Let's hope we find out quickly what happened and get it corrected.