It’s a literally different ELAC standard, which needs to be upgraded to L97+, in and of itself more than a few weeks of work. Manoeuvre Load Alleviation/Gust Load Alleviation (MLA/GLA) function, STOP RUDDER INPUT messages and aural warnings, changes to flight control laws with regards to the transition flare law to ground law. Modification of the transition logic from flight lateral normal control law to ground normal law. New conditions for CAS, limiting THS up deflection… Deflection rate of the elevator is also changed on ground. Angle of attack and Pitch Angle conditions used to revert in unusual laws have also changed.
Electrical transfer around 3 seconds with three hydraulic pressure low, and aircraft electrical power up with one hydraulic pressure switch detecting high pressure within only one ELAC unit now changes the ELAC FAULT messaging also.
Additionally the change to the flight model for sharklets means it’s a new and different fly-by-wire tuning to account for the overall lift changes. Which means it’s a new set of AP PID tuning. The fuel system (can) be different for SL aircraft with jet pumps vs. the old style. Different lighting. The fuse is different on SL aircraft vs. what we have modelled. The TERR is different and should be outfitted with PEAKS mode.
I could go on, and on, and on, and on. Of course you don’t notice any different actually flying the airplane. That’s because engineers have spent thousands of hours adapting and changing things to build this thing so it doesn’t change that much. But if you change the conditions or inputs to a highly digital system, the entire thing goes out of whack unless you modify the digital processing and behaviour also.
It is *not* just a visual model change.