Commercial aircraft designs are transitioning from primarily aluminum construction to composite skins with aluminum and titanium substructure.  Aggressive performance and fuel efficiency requirements are requiring more focus on lightweight titanium substructure.  In areas of aircraft structure which are lightly loaded, titanium is still desired for corrosion and stiffness characteristics, but the manufacturing minimum gauge can be higher than required for carrying loads.  Advanced machining technologies are enabling weight reduction through reduced minimum gauge and small corner radii in deep pocketed, monolithic titanium.  Traditional uses of high speed steel cutting tools and single step finishing results in a hard limit of manufacturing minimum gauge.  The use of modern indexible and solid micro-grain tungsten carbide is coupled with thin wall machining approaches, plunge milling and end milling to enable lighter, less expensive titanium machinings.