So, if I follow this correctly, the "sandstone" texturizer is applied only to the HeloRampLight_LM.psd file that is intended for use in "Self-Illumination: Map #6" as seen in the GMAX Material Navigator in your Post #6 above ?
Um, not quite. Map#282 HeloRampLightSplash_spec.psd file is the one.
Yes, that is one method, although if using the FSX Imagetool the "flipping" is done automatically.And IIUC, after that material (and all others in the project) have been mapped to the 3-D model in GMAX, when final output files are created, those mapped *.psd files must all be copied, "flipped", and converted to *.DDS files for use in FSX using a graphics utility (ex: FSX SDK ImageTool) external to GMAX itself ?
Personally I use the nVidia DDS plugin and simply "flip vertically" then SaveAs DDS directly from Photoshop. It's much easier, faster, and less effort...