Advanced Structural Materials
Use of advanced materials allows considerable structural weight reductions throughout the 747-400. Metal flooring, previously used in the passenger cabin, was replaced by light, tough graphite composite floor panels.
Structural carbon brakes are standard on the 747-400's 16 main landing-gear wheels. They provide improved energy absorption characteristics and wear resistance, as well as an estimated 1,800-pound (816 kg) weight savings over previous brakes.
The 747-400 also achieved weight savings of approximately 4,200 pounds (1,900 kg) by using higher strength aluminum alloys with improved fatigue life. These alloys are incorporated in the 747-400's wing skins, stringers and lower-spar chords.