I'm currently rebuilding the EC135 helicopter for the OpenSource FlightSimulator FlightGear.
For checking the right proportions I use several renderer like yafray and at least of course, Indigo!


I struggle with some problems: there is a strange black effect on the fuselage and parts of the tail and fenestron.
The heli is poly-by-poly modelled and in Blender with the "modifier-> Smooth" and "Setsmooth" smoothed.
I wonder why and how can I solve this?
Regards
HHS