That happens often, that some of the models which cannot be converted with PCS still work with cob2fs2 (until they aren't too highpoly). Actually it is really hard to tell, where the problem lies (without seeing it in wireframe and 3D) according to these pictures. When speaking about geometry-errors there are most likely not visible if even visible at all, still PCS will hate them.
The model looks rather simple (in geometry), so normally PCS would have no problem if everything would be O.K.
Are the wings connected to the centerpart, or are they seperate objects. ? If your models contains seperate objects, starts deleting them for testing-purpose to detect the one actually damaged.
However, according to what I've learned so far, I would suggest you start on these two points, escpecially the knicked face in the intake (don't know how you created them). If you deformed (and not point-moved) the mesh there, it could be the problem. Still, these are only suggestions, but could be worth a try.
(Sorry for the bad arrow-drawings

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