Not that is a blocking problem, but for robustness, when exporting an .obj as AS class, when only exporting the mesh(no lights, images, etc), the resulting class file
...
var flipper:Mesh = buildMesh(new Geometry(), flipper, “flipper”, nullnull);
...
the resulting class, needs to add this line in the imports section:
import away3d.core.base.Geometry;
and the nullnull, needs to be separated by comma, null,null.