Unabel to install the first leading edge rivets (2 rivets) at the tip of the VS. Rivet squizer or bucking bars would not fit into the inside flange at the tip of the VS. Unable to install 4 rivets on the aft spar at the center hinge. Threre was insufficient clearance between the rivets installed through the hinge on aft spar web and those on the aft spar flange . Ground bucking bar to fit allowing installation of the four rivets on the aft spar at the center hinge.