Oh yeah, CAD for maintenance manuals. The engineering design system, that's a great place for parts lists.

This was always a fun one. We realized right away that the data in the CAD models was superior to the technical drawings we received as PDFs (most of which, awful scans of paper documents). However, only the technical drawings were acceptable for the type-certificate. Our manuals were part of the type cert, so we had to verify everything agains the crappy PDFs anyway.