Lowfat, not quite sure where your last sentence comes from (other than a desire to be rude for the sake of it) so I'll ignore it.
The Bond aircraft was new and had a slightly modified shaft with the reprofiled hole. Fortunately no Bristow aircraft had that mod state of shaft.
The CHC aircraft, as has just been explained, had unusual operating conditions which (may) have accounted for its corrosion. it had relatively high hours on the gearbox, but so do plenty of ours. But anyway, for whatever reason, it had much more corrosion than any other 225.
Make of all that what you will, but those are the simple facts.