Brother Dixson might be able to confirm my foggy memory of an account by another Sikorsky Notable that reported the S-76A VNE could have been higher but the expense to test/document/certify the additional speed was deemed un-economical and thus was not done.
Determination of Vne is controlled by Section G.
What is interesting is the FAA requires the data used to compute Vne displayed to the Pilot have no more than two Parameters for the Pilot to consider to reduce the Mental Effort required.
https://www.faa.gov/documentLibrary/...hru_Chg_6_.pdf