 The airframe is built with about 80% aviation-grade aluminum alloys, 8% steel, 3% composites, and 1.5% titanium.The leading-edge flaps, stabilators, and ventral fins make use of bonded aluminum honeycomb structures and graphite epoxy lamination coatings.The number of lubrication points, fuel line connections, and replaceable modules is significantly lower than preceding fighters; 80% of the access panels can be accessed without stands.