The 30 minute loss-of-lube MRGB qual test requirement with the DoD and FAA exists because rotorcraft MRGB lube systems are prone to failure by nature. And there is no practical way to make any MRGB lube system fault tolerant enough to have it's failure considered a "remote possibility". The MRGB lube system is simply too complex, and too critical for flight.
Having said that, I don't honestly believe that Sikorsky's engineers intentionally disregarded the safety of the S-92's MRGB design. Achieving a 30 minute loss-of-lube capability in a high torque MRGB is incredibly difficult to do. But that doesn't mean they didn't make mistakes.
For example, take a look at this photo of an S-92 MRGB lube system filter housing from a fatal crash:
http://www.flightglobal.com/assets/g...x?ItemID=29667
Although it's hard to say for sure, but it appears that the o-ring seal on this filter housing is a "face type" seal. Normally, a "radial type" o-ring seal would be used for something like this filter housing. The reason being that a "radial type" o-ring seal would not result in leakage like a "face type" o-ring seal would, in the event of a single fastener failure as shown in the photos.
The design of an o-ring groove is just a simple thing, but obviously such design features can mean the difference between life and death in some instances.