@Magnum164 Hey, I recently also incorporated the F16, and using the latest version of the JSBSim plugin for unreal - which sets a constant update rate of 120hz to the FDM - plus forcing a constant FPS on unreal, the oscillations around 550 knots were completely eliminated. So, if you are still having problems with the oscillations, I’d recommend to just download the new plugin version, and setting a top FPS on unreal (can be done with the console command t.MaxFPS).
That said, it seems that I nevertheless hit roll oscillations again at 1160 knots 
I wonder what those are about… Is it a problem with the FDM’s integration frequency again? Or are those to be expected also in reality? Or is it due to some other problem…?