Sven
That might be true if the oil filter were the only possible source of oil loss from the MGB. Unfortunately its not - as has already been suggested, there are other weak points such as entry/exit points of drive shafts, and of course the possibility of a crack in a lower region of the MGB casing, which has happened plenty on the 92 MGB already (fortunately not large enough to release significant quantity of oil so far.)
But lets not lose the plot here, whilst the 92 clearly doesn't meet the 29.927 and so technically should lose its certification, neither do lots of other helicopters that fly around carrying oil workers over hostile seas, simply because they were certified before 29.927 existed in its current form - in the UK thats pretty much everything apart from the 225 and 139.
As people are saying, 30 mins dry run time doesn't necessarily stop a ditching (though here in the N Sea you are pretty much always within 30 mins of somewhere to land) and as Robert Decker himself said, what is of primary importance is to stop the helicopter ending up in the sea in the first place. Therefore concentration should be on preventing the oil loss etc in the first place, rather than what you are going to do once its all gone.
So I don't think the S92s should all be grounded pending compliance, however it is especially gaulling to consider the arrogance by which Sikorsky proclaimed the S92 to be the safest helicopter in the world whilst at the same time they were in full knowledge of its failure to comply with the spirit of 29.927.
And since the safety of any helicopter hangs by a tenous thread, any time a manufacturer gets arrogant (which implies complacency), that should be a danger sign!
HC