I used to fly Mi-24's. Finest gunship ever made, bar none, and don't go pushing your Apaches on me. They only carry 3, the 24 carries 10 plus the same loadout, and it can survive a serious hit without after market parts.
But yep - recoil damage to the airframe is brutal on most aircraft. We'd get warned on some of the birds not to use the cannon unless it were an emergency (and that were only .50 cal.). You could hear the frame creaking in complaint. One guy - not on my flight - actually deformed the frame enough to pop out two of the windows in the loading hatch. Must have been an interesting ride for the poor sods in the back!
Think the only beast that simply won't fail is the Warthog. The gun is not attached to the airframe itself, but to two huge and heavy steel rails. Spreads out the stresses, or something like that, instead of localizing them on smaller mounting points.