http://rgl.faa.gov/Regulatory_and_Gu...meset?OpenPage
In the above link (search for Sikorsky) there is a list of the Sikorsky S92A Equivalent Level of Safety certificates which, I believe, have to be completed in cases where the design of the aircraft does not meet the FAR standard. The manufacturer then has to produce evidence that the proposed design meets and equivalent level of safety; the FAA then issue a certficate to confirm this.
The MRGB with the lack of 'run dry' capability surely should have had such a certificate since it did not meet the FAR requirements and Sikorsky had to show that the failure was extremely improbable.
How did they get certification without a ELOS certificate for the MRGB?