Air Chathams ATR 72-500 texture for the OSP ATR 72-500 base model.
These are textures only. The OSP ATR 72-500 base model is required.
It can be found at www.avsim.com. Search for osp_atr_72_500_base.zip.
P3Dv4 converted models can be found at Alpha India Group FTP:
https://www.alpha-india.net/aigfiles/files/Converted%20P3D%20v4%20models/OSP%20ATR72-500%20P3Dv4%20Lua%20v2.zip