How does lightning impact a composite airliner like the Boeing 787?

Lightning strikes pose unique challenges for composite airliners like the Boeing 787, primarily due to the differences in conductivity between composite materials and traditional aluminum used in earlier aircraft designs.

Impact of Lightning on Composite Airliners

1. Conductivity Differences:

   • Aluminum Aircraft: Traditional aircraft, made mostly of aluminum, are highly conductive. When lightning strikes, the electrical charge typically spreads evenly across the aircraft's surface and safely exits through points like the wingtips or tail, minimizing localized damage.

   • Composite Materials: The Boeing 787 is made largely of composite materials, such as carbon fiber reinforced plastic (CFRP). These materials are much less conductive than aluminum, making them more susceptible to localized damage when struck by lightning. Without adequate protection, the electrical charge from lightning could cause severe damage by seeking out conductive paths through the aircraft, such as wiring or hinges, leading to burn marks, holes, or even critical system failures.

2. Lightning Protection Measures:

   • To address the lower conductivity of composite materials, Boeing added a network of conductive materials, such as metal mesh or foils, embedded within the composite skin. This layer is designed to create a pathway that guides the electrical charge safely across the aircraft's surface and minimizes damage to the underlying structure.

   • This protection system is essential but adds additional weight to the aircraft, which was a challenge during the development of the Boeing 787. The extra weight was one of the factors that pushed the Dreamliner over its initial target weight, complicating the design and impacting performance expectations.

3. Damage from Lightning Strikes:

   • Despite these protections, lightning strikes can still cause visible damage, such as burn marks and small puncture holes on the aircraft's surface. After a lightning strike, it is standard procedure to conduct thorough inspections to assess any potential damage before the aircraft is cleared for further flights. The damage is usually superficial, but it must be repaired to ensure the integrity of the aircraft’s lightning protection system.

   • Composite materials, while offering benefits like weight reduction and improved fuel efficiency, do require more sophisticated and sometimes heavier protective measures against lightning. This trade-off is a key consideration in the design and maintenance of modern composite airliners like the Boeing 787.

While the Boeing 787's composite structure presents advantages in terms of weight savings and fuel efficiency, it also requires careful management of lightning strike risks due to the lower conductivity of composites. The added protective materials and subsequent inspections after lightning strikes are critical to maintaining the safety and airworthiness of the aircraft. These challenges underscore the balance that must be struck between advanced materials and traditional safety requirements in modern aviation design.