Devices for maintaining crawler alignment on complex-shaped blades and for enabling the blade crawler to traverse over trailing edge protrusions. Using ball and socket bearings or air pads in place of alignment wheels, the crawler will be able to track along complex-geometry rotor blades, propellers and other airfoils. Using an oversized-diameter roller, a semi-flexible roller, or a dual-roller arrangement, the crawler will be able to traverse over trailing edge protrusions.