Rare, but occasionally a wing refuses to come off the airplane due to corrosion inside the spar joint. This wing was sent to us to repair after the wing was twisted so hard that it cracked all of the ribs at the spar collars. There have been some so stubborn that the fuselage and wing had to be chained to the concrete with jacks placed along the trailing edge to get it to move any. Once it moves then the hard work starts.