Grounding and Bonding in Aircraft

The Anatomy of ESN Lightning Strike Technology Lightning usually strikes an aircraft on the nose or other extremity points such as wing- tips or the vertical stabilizer. For this reason, the aircraft nose and other extremity edges are generally equipped with light- ning diverter strips to arrest the current and dissipate it across the fuselage. The aluminum or conductive composite fuse- lage of the aircraft is an integral part of the ESN and conducts the discharge along the outer surface of the aircraft to an exit ground point. The fact that all this occurs without serious damage to the aircraft or injury to its passengers is because the fuselage is a highly- engineered Faraday cage. A Faraday cage is an enclosure made of conductive material that is designed to block exter- nal electromagnetic fields. As stated, the aircraft fuselage is primarily made of conductive materials, such as aluminum or composite thermoplastic with conductive layers. These materials have low electrical resistance and allow for effec- tive conduction of electric charges. When a lightning strike occurs, the conductive struc- ture of the fuselage provides a low-resistance path for the lightning current to flow around the exterior of the aircraft. This means that the majority of the lightning current will flow through the external conduc- tive structure rather than entering the aircraft’s interior. As the lightning current flows over the outer surface of the plane, its energy is distributed across the conductive struc- ture. This helps to prevent concentrated current paths that could lead to localized damage, reducing the risk of structural or equipment failure.


Electrical Component

Composite Structure

Exposed Foil or Mesh Ground Plane

Component Mounting Bracket


Exposed Foil or Mesh Ground Plane

Reinforcing Washer

Bonding Wire

Composite Structure

Electrical Bonding in Composite Aircraft In aircraft construction, composite materials offer improved strength-to- weight ratio compared to aluminum. However, these materials exhibit high electrical resistance and inhibit bonding, earth returns, and lightning strike dissipation. This lack of electrical conductivity requires integrating a ground plane into the composite airframe. Typically, an expanded copper foil or wire mesh (or other high-conductivity material) is bonded into the composite structure during the manufacturing process and can be accessed at key points throughout the aircraft. Direct bonding (top) involves exposing the foil or mesh—the ground plane—and mounting equipment onto the conductive path. Comparatively, indirect bonding (bottom) requires installing a bonding wire and connector onto the exposed foil or mesh. After establishing the connection, the mesh must be coated to prevent the aluminum from oxidizing when exposed to air. Oxidation will compromise joints and increase electrical resistance. To protect a composite aircraft from lighting strike, aluminum wire is integrated into the outer layers of the composite construction. This integrated wire construction offers fixed exit routes which dissipate the lightning strike across the extremities of the aircraft.

QwikConnect • July 2023


Powered by