Boeing 787 Dreamliner - Mark Wagner [42]
Cytec was also to supply the fuselage assembly partners with a surfacing film that was spread over the skin after molding to reduce the amount of sanding needed before painting. As an intermediate barrier coating, it also meant that airlines could change the colors of the paint without necessarily having to sand all the way down to the composite.
METALS FIGHT BACK
Although most of the news about the Dreamliner put the limelight on the composite industry, the traditional aerospace metals suppliers also had reason for cheer. Although the switch to composites for much of the primary structure, previously the sole domain of aluminum, was an obvious concern to the metals industry, the 787 still contained 20 percent aluminum by weight, and the sheer production volumes would guarantee big business for suppliers such as Alcoa. The aluminum specialist was picked to supply its proprietary 7085 alloy, mostly used in areas such as wing spars and engine pylons, and the estimated content value on the 787 was close to that on the 767.
Boeing’s Australian subsidiary Hawker de Havilland produced the wing movable trailing edge package, including the aileron and flaperon seen here. The work included supply of the associated hinged panels, the inboard and outboard flaps, seven spoilers per wing, and all the fairings. The sections were all made using a vacuum-assisted resin transfer molding (VARTM) process originally aimed at the Sonic Cruiser. EADS also uses this process, which does not require an autoclave, for the 787’s all-composite aft-pressure bulkhead—another first for a Boeing jetliner. Mark Wagner
Titanium makes up to 15 percent of the 787, the biggest share after composite (50 percent) and aluminum (20 percent). It is the first major aerospace application of a new, stronger type of titanium alloy called 5553. To feed its increased appetite for this important metal, which is 60 percent heavier than aluminum but twice as strong, Boeing and Russian supplier VSMPO-AVISMA announced a joint venture in 2006 to machine titanium forgings for the 787. Under the 50:50 deal rough machining of forgings was performed in Verkhnaya Salda, Russia. Final machining and processing of the forgings were completed at Boeing’s Portland, Oregon, fabrication facility and by other machining subcontractors. Mark Wagner
However, aware of the squeeze from composites and the growing use of titanium, Alcoa wanted to protect its turf and continued to study a higher-strength, lightweight aluminum-lithium (Al-Li) alloy as a potential future material. By 2007 it was working on Al-Li alloys for plate, rather than sheet, products designed to be machined to produce lighter, simpler monolithic parts. Alcoa believed this could provide Boeing with a weight-saving alternative to the strategically vulnerable titanium.
Alcoa also developed other crucial components for the 787 such as a titanium hydraulic adapter for the aircraft’s 5,000 psi system. Alcoa said the system provided 49 percent weight savings over previous designs. With a 15 percent share of the structure by weight, the new twin was easily the biggest user of titanium of any airliner. Compared to the larger 777, which required 139,000 pounds of titanium, and even the far bigger A380, which consumed 150,000 pounds per aircraft, the 787 would require about 250,000 pounds of the raw material per aircraft. The material had the advantage of being lighter than aluminum and more compatible with composites than aluminum, sharing a similar coefficient of expansion. Additionally, it did not corrode when in contact with composites.
A new grade of titanium, named 5553, was developed for the 787. To support the