Hi there, welcome to SimV!!
From what I can see, I guess you have the following problem:
I assume you use Gmax for modelling? well, if so, then I assume you used the mirror button in Gmax to mirror the wing? That is where your problem is. the mirror looks fine in Gmax, but when exported, it also invert the whole plane, From your shadow, it looks like the wing does not have the bottom half.
to rectify this:
delete the wing in Gmax, and select the to mirror it , go to the mirror function in the modifier list.
I hope it helps - -if I guessed correctly?