There are a couple of possibilities; on most airplanes, the wings are attached to the fuse., by "male and females"
castings; a bushing goes across the hole and a close tolerance bolt attaches everything...
Years ago, we experienced the same issue, and finally they increased the tolerances between these parts , allowing them to "float": problem solved.
The other possibility is air in the hydraulic system; the banging can be quite alarming if you don't know the cause of it.