It sounds as thought the balsa was not bonded to well to the wing structure. Is this a built up wing or a foam core? Foam core, clean as much Spackle as you can off. get some water based glue, such as good ole Elmers, thin with about 20-25% water, use a thin plastic sheet as a way to get the glue under the balsa, get as much area covered as you can. Either make a cheap vacuum bag out of a shop vac to hold the balsa as tight as you can. If you can cut a foam block into the shape of the wing you could use that as a mold to squeeze the balsa tight again.

Built up wing, drill small holes along the top of the ribs, wick ca into the holes to glue the balsa down again. Fill the crack with a long sliver of balsa, glue well, sand. I use Elmers with the orange top. It is the color of balsa, sands like balsa, take paint, covering, like balsa.

Lots of work to fix a warped piece of would.


Buzz.