Sorry .. I was too enthusiastic and when checking the .x file (generated with blender 2.49 exporter to DirectX) I was looking only the "solid view" in MCX ... early this morning I was looking to the .x files, imported in MCX, textured ... and discovered the taxtures were completely mixed up !

I tried ... don't really remember now ... to much confused ! And made a mess also in the blender file ... at a certain ponit I discovered the one object was textured with a ".bl" file, coming from where ?? And naturally MCX was not recognizing it. Worked on the .x file modifying it with a text editor, to turn the fancy .bl to .png ... After that, no .bl was apparent in the .x file ... but it was always showing an error in the MCX events log:
"Failed to load "Texture.bl" "
Luckly enough I was invited to have a one hour flight on a real Cessna C150 on he Alps