Posts Tagged “Lightning Strike Protection”
A British Airways Boeing 787-8 (G-ZBJG) was struck by lightning shortly after departure from London Heathrow on July 22nd en route to Chennai in India. The flight, BA35, continued on the 9 hour flight to India, but upon landing it was discovered that the aircraft had 42 to 46 holes in the fuselage from lightning strike damage. This was an unusual level of damage to a 787 and the worst outcome to date from a lightning strike to that aircraft type.
While the flight completed the trip safely, British Airways decided to return the aircraft to London on July 29th without passengers to undergo maintenance. A day later, the aircraft was returned to service, a week after the incident.
With metal aircraft, electricity can easily be conducted across the skin to a wing-tip or other edge from which lightning can easily be dissipated. Composite aircraft are built with metal foil, woven wire, or most commonly an expanded metal mesh to dissipate the impact of lightning strikes. The two aircraft with more than 50% composite material, the 787 and A350, utilize different approaches to lightning strike protection for their composite fuselages.
This incident, which caused a one week loss of revenue on a 787-8, indicates that while passengers remained safe, the aircraft required specialized maintenance that apparently could not be performed locally once the aircraft landed, necessitating an expensive ferry flight back to its home base.
Repairing damage to metal aircraft is fairly straightforward, as a “scab patch” is placed over a damaged area and riveted in. Composite aircraft require a more complex repair process that requires removing the damaged composites from affected areas, replacing them with new material that includes new lightning strike protection, and heating that area to cure and chemically bond the new material to the existing composites. This incident shows just how expensive that process can be on the Boeing 787.
Have you ever wondered how composite materials, which unlike metal, don’t conduct electricity, can withstand lightning strikes? The answer is that they use a tailored solution of expanded metal, a very thin sheet of lightweight perforated metal that is embedded into the composite materials to diffuse a lightning strike that would otherwise puncture the composite structure. That material, for most commercial aircraft and business jets, is manufactured by Dexmet Corporation in Wallingford, Connecticut. (more…)