Building the 787 | When lightning strikes

interesting facts.

In November, one top safety-engineering team expressed serious concern.

That team's internal review, obtained by The Seattle Times, concluded: "It cannot be shown that the current wing-lightning-protection approach will preclude ignition sources in the fuel tank."

although one way would be to inert the air in the tank with nitrogen purges

which boeing is doing

• And, in case the efforts to shut out ignition sources fail, Boeing will install a nitrogen-generating system (NGS) that reduces flammable vapor in the wing tanks by filling the space above the fuel with inert gas.

Typically, a bolt moves backward across a wing or fuselage before the charge exits to the ground milliseconds later. At the point of entry on a metal skin, the aluminum can melt, leaving a pitted surface or a small hole.

"You can't hit aluminum with 200,000 amps and expect nothing to happen," Gillette said. "But it's not a safety-of-flight issue."

In 1963, over Elkton, Md., 81 people died when the fuel tank of a Pan Am 707 exploded in flight, apparently after being struck by lightning. In 1976 near Madrid, Spain, all 17 people aboard an Iranian Air Force 747 jumbo jet died when a lightning strike to the wingtip ignited the jet fuel and blew the wing apart.

Building the 787 | When lightning strikes



[edit on 5-3-2006 by bigx01]