7/19/2010
HEADLINES
Boeing Patents Fastening System For Dreamliner
Boeing received a patent on a fastening assembly for composite structures “that will reduce or eliminate internal sparking and prevent hot gas from escaping into the structure when it is hit by lightning,” Bloomberg reports.
Patent 7,755,876 comes weeks after Boeing’s composite 787 Dreamliner reportedly survived its first lightning strike.
While lightning typically dissipates across the metal body of the airframe on most airliners before discharging into the ground, the 787’s less-conductive carbon-fiber skin, which requires 40,000 fewer aluminum fasteners, forced Boeing to design special lightning protection to avoid severe damage at the location of a strike.
“A lightning strike near an ordinary fastener can quickly produce a high current density entering the body of the aircraft through the fastener,” according to the patent.
A key element of the patented fastener is a washer that can contain hot gasses and prevent arcing.
One of Boeing’s test 787s reportedly was struck in May during a thunderstorm near Boeing Field. The aircraft’s systems, fuselage and wings all appeared to be undamaged after the strike.
Engineers paid special attention to the 787’s wing fasteners “to avoid gaps that could cause sparking in the wings’ fuel tanks during a lightning strike.”
They also embedded a thin copper mesh beneath the outer layer of the airplane’s skin to disperse the current from a strike.
Boeing applied for the patent in June 2007. ©2010 GlobalFastenerNews.com
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