Trinity Core does not Install accesories on vehicle creation from vehilce_template_accesory.
After the vehicle uses a reset script everything is great.
Example:
Say you made accesories for Kologarn on Ulduar.
http://static.wowhead.com/uploads/screenshots/normal/127344.jpg
When you enter the room hes armless /emoticons/default_biggrin.png
After a whipe the arms apear.
Enyone knows where to put InstallAllAccessories() or something?