My bad. First i just wrote "usable chopper ramps" into the summary field and i searched for that, but later when i edited summary i didnt search for "walkable interior".

i hope they will fix this once...

I guess its because the turret's motor got unlimited power and the building is either undestructible or just needs more damage than a tank turret can do to collapse. If iam right than the mod creator should set a torque for that turret rather than a fix speed.