MDL file format (FSX)
From FSDeveloper Wiki
This document describes the structure of FsX MDL files. This document is mainly useful for people who want to read or decode these MDL files in a tool.
Compared to the Fs2004 MDL format there are quite a few changes. One of the biggest is that aircraft and scenery MDL files now have the same format. At the moment the knowledge in this document mainly comes from evaluating simple scenery objects, so it is certainly not yet complete. If you have anything to add, please do so.