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Boeing Shares Drop
After Boeing Reported Composite Structural Issues In The 787 By Steve Hall |
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February 7, 2012 - On Monday Boeing shares fell on the
New York Stock Exchange after the aircraft maker
reported it will need to take corrective action on the
787 Dreamliner carbon-composite fuselage support
structure.
The first Boeing launch customer, All Nippon Airways
took delivery of the 787 Dreamliner on September 25,
2011, at Boeing's facilities in Everett, Washington. On
September 27, the Dreamliner flew to Haneda Airport. The
airline took delivery of the second 787 on October 13,
2011.
The Boeing 787 contains approximately 35 short tons of
carbon fiber reinforced plastic (CFRP), made with 23
tons of carbon fiber. Carbon fiber composites have a
higher strength-to-weight ratio than traditional
aircraft materials, which helps make the 787 a lighter
aircraft. |
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Composites
are used on fuselage, wings, tail, doors, and interior. Boeing
had built and tested the first commercial aircraft composite
section while studying the proposed Sonic Cruiser nearly five
years before the Bell Boeing V-22 Osprey military transport
which uses 50% composites, and the company's C-17 transport has
over 16,000 lbs of structural composites.
Composite
materials are made by combining materials such as carbon fibers
with epoxy, they have been used in airplane components for
decades. Although composites are lighter and stronger than most
metals, their increasing use in commercial airplane structures
such as the fuselage and wings has raised safety concerns (The
GAO Raises Safety Concerns Over The Boeings 787).
Carbon
fiber, unlike metal, does not visibly show cracks and fatigue,
which has prompted concerns about the safety risks of widespread
use of the material the rival Airbus A350 was later announced to
be using composite panels on a frame, a more traditional
approach, which its contractors regarded as less risky. In addition, the porous properties of composite materials, which may cause delamination as collected moisture expands with altitude, is a potential issue. Delamination is a mode of failure for composite materials. Modes of failure are also known as 'failure mechanisms'. In laminated materials, repeated cyclic stresses, impact, and so on can cause layers to separate, forming a mica-like structure of separate layers, with significant loss of mechanical toughness. |