I’m not sure if this is the right forum to post this, but I don’t know what the problem is. In the attached image, if you look at the nacelles, the one on the left has weird dark spots, and the one on the right has white spots (they’re dark spots hit with direct light I think). The problem isn’t doubles, flipped normals, or non-manifold, as far as I know, and only shows up in the render, not during live edit. What could it be?
looks like smoothing artifacts. try beveling those edges a bit, or adjust the smoothing angle on the ‘Mesh’ panel?
You suggestions didn’t work, however, I discovered that by deleting the trouble spots and re-connect the dots, it fixed the problem.
edit: The problem seems to do with the subsurface crease being set to 1 and .9 at different places,
ah! good. glad you got it figured out. that would have taken me some time to diagnose, on my own model.