Turboshaft,
I just don't think anybody knows where you are tryi to go with the TBO thing. You keep talking about the extensions on the MGB that was removed. That gearbox is gone to overhaul, with no incident and is not in question. We got that. Then the 1300 hours since January, which is not possible, but even it was, you have already stated the TBO to be 2000. Meaning the gearbox in question would still be 700 hours shy. It is possible that a gearbox with 1300 hours was installed, as already mentioned, but that gearbox would still no likely make it to 2000 hours in 3.5 months either. I'm sure some of the other guys can pipe in, but I'm use to the average yearly hours on an offshore aircraft being between 1000-1500.
Maybe you need to explain exactly what you are getting at rather then going off about extensions. Extensions are a normal part of the aviation industry.