We have found one software suitable in our database for this conversion.
FreeCAD drawings (.fcstd) can be exported by the program to all kinds of other 3D data, including IGES format (.igs, .iges).
Unfortunately, we do not know about any program that could otherwise perform fcstd to iges conversion as .fcstd files seems to be exclusive to FreeCAD.
FCSTD
Files with fcstd extension are CAD drawings from FreeCAD, a parametric 3D modeling software for Windows, Mac, Linux. An fcstd file stores drawing.
IGES
Files with igs extension can be typically found as 3D graphics data saved in International Graphics Exchange Standard (IGES) format used for data exchange.