Red Wine: I have been wondering that also. The only other major incidents (to do with main rotors) that I am aware of, are to do with the R22 in the mustering industry.
I'm fairly sure the operator with the R44 in question is purely in the charter catagory and does not muster, but does fly coastal in the tropics. Hence the corrosion theories.
I was thinking somebody else would add similar experiences either from Oz or around the world but it seems that this may be the first incident in a R44.