[Reflective/Glossy Texture on Aerosoft Airbus A320/321 Pro in P3Dv5(5.3)]

Hey, I'll answer you before anyone else does. LM changed the legacy shader with P3Dv5.1 (or 5.2). Unfortunately, this leads to the fact that the small Airbus looks like he looks. But this does not only affect the 320 family, also the 717 from TFDi looks the same in 5.3. Unfortunately, nothing more will come from Aerosoft here. For reasons. The official answer is that they would have to rework the models to be able to implement "real" PBR. More likely is that P3D is dead for Aerosoft and they do not want to put any more effort in here. And we as customers have to live with the fact that our purchased product looks like crap from the outside. 
For the 717 there is at least a PBR mod in the TFDi forum. For the 320 family unfortunately not.