Hi,
I know that the plumbing is already there. however they will need to test it as well by performing mid-air refueling tests. So that's why I asked as this jet was supposed to have it from the start as stated previously by the program director.
They are not going to be conducting air refuelling on the first flight.
Flight testing is all about minimising the unknowns and risks while making small, incremental advances.
It's little different in this case.
The internal structure and weight distributions would have already been changed by the new plumbing for IFR as well as the updated avionics and other improvements. Block 3 represents a lot of changes and improvements, with the IFR only the most visible one, but it is probably not the most significant or important.
You don't want to add the extra external drag changes a fixed IFR probe will add to the mix as well on the first flight.
So it makes perfect sense to get some flights done first to make sure everything is as expected with how the plane handles clean with the new internal changes first before flying with the probe.