The Seattle Times has been running a series called “Building the 787″ and recently an article on “When Lightning Strikes” caught my attention.

The article outlines the new technologies and improvements Boeing is making in the 787 involving lightning strikes. While new protection systems prevent many problems associated with lightning strikes, the articles states no airline crash has been caused by lightning in more than 40 years, an amazing accomplishment since Boeing estimates “that every commercial airplane is hit by lightning on average about twice a year.”

Boeing engineers designing the 787 face new challenges, since they are building the first commercial airframe made entirely from carbon fiber-based plastic.

The composite airframe will not readily conduct lightning away, as traditional metal ones do.

That means Boeing will have to do more to prevent lightning from damaging the planes, said Ed Rupke, senior engineer with respected consulting firm Lightning Technologies of Pittsfield, Mass.

An airplane often actually triggers a lightning bolt to the nose, the leading edges, the tail or the wings as it flies through an electrically charged cloud. The main danger airplane designers must guard against is sparking inside the wings, which serve as the jet’s main fuel tanks.

Most of the time, after a flash and a bang, lightning damage is minimal, and airplanes fly on to their destinations.

With the new 787 constructed on a plastic airframe with composites, lightning protection becomes a major concern.

After a decade of serious accidents internationally from lightning strikes on aircraft, the FAA increased safety requirements and protection systems in the early 1980s.

What caught my attention the most was the interesting “multilayered approach to lightning protection of the 787 fuel tank” that Boeing is taking. Here are excerpts from the article:

  • The initial lightning strike must be dispersed quickly around the airframe to prevent concentrated damage.
  • The airplane’s electronic flight instruments must be shielded from disruption by the intense electromagnetic field.
  • A slight gap between a wing-skin fastener and the hole it goes into could be a source of sparking as current jumps the gap. Boeing will install each fastener precisely and seal it on the inside to ensure a snug, spark-free fit.
  • Any gap inside the wings where the wing skin meets internal structural spars could cause a spraying out of electrons in a lightning strike — a phenomenon called “edge glow.” Boeing will seal the edges with nonconducting goop or glass fiber.
  • 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, as a backup in case other methods fail.