I think gullibell's post is relevant.
It points out that there are not a lot of huge design differences in most helicopter MGB's.
These components are invariably not made by the OEM.
There are plenty of MGB failures that are not catastrophic and there are some that but for some grace easily could have that do not get into the public domain.
Something really obscure happened here.
There are a large number of factors in this accident and some that may be difficult to trace unfortunately, for various reasons, which will make any fix possibly beyond economic as it seems.