I am uploading a corrected Avia 51 FSX version to my site for the missing textures.
I also corrected the autopilot function.
Should be ready within 30 minutes.
EDIT: Revised Avia 51 for FSX now loaded and ready for download from my website.
For those already having the FSX installed with the SCW texture that would like a corrected aircraft.cfg for the Autopilot function, it is attached.
Otherwise download the latest version that includes the SCW version and the corrected aircraft.cfg AP function.