An aircraft can experience a lightning strike when flying through a region with high electrical activity or thunderstorms. This is a fairly rare occurrence, with commercial planes getting hit by lightning only about once a year on average. Lightning will generally hit the nose, tail, or wingtip. It then moves along the aircraft’s exterior and exits through another extremity.
When designing protective materials, engineering teams consider the various ways a lightning strike can negatively impact an aircraft’s structure and systems. For instance, burns or minor punctures on the aircraft’s skin could cause structural damage. In some cases, the force of the strike could cause significant damage to composite materials in the aircraft.
Lightning strikes can also affect electrical systems, including navigation equipment and avionics. An electrical surge could damage or disrupt these systems. Fuel lines and fuel tanks are especially vulnerable; without proper protection, the fuel system could ignite. Below, we’ll discuss the key design principles used to protect aircraft from the damaging effects of lightning.
Principles of Aircraft Lightning Protection
Faraday Cage Effect
A Faraday cage uses expanded metal foil (EMF) or other conductive material to trap electric fields inside or keep them out. The conductive material can easily be incorporated into aircraft systems and used on the outer surface of the aircraft.
Lightning that strikes the aircraft fuselage carries a high-voltage electrical current. The Faraday cage transfers energy from the lightning to the outside of the aircraft by spreading it throughout the plane’s body. The conductive structure stops the electric current from reaching the interior of the plane, instead distributing it across the outer body of the plane. This distribution protects sensitive electronic equipment and passengers inside the aircraft.
Path of Least Resistance
When lightning strikes an aircraft, it is most likely to make contact with the nose, wingtip, or another extremity protruding from the body of the plane. The charge continues to flow along the aircraft’s skin, exiting through the opposite wingtip, tail, or another extremity.
Key Components of Aircraft Lightning Protection
Conductive Materials
An aircraft’s skin includes aluminum and other conductive materials that create a protective layer around the carbon fiber. These materials enhance aircraft lightning protection by creating a path for the electrical charge to travel along. Most external parts of an aircraft use metal with sufficient thickness and performance capabilities to prevent electrical currents from penetrating the outer surface.
Expanded Metal Foil (EMF)
EMF is commonly used in aircraft construction. Manufacturers slit and stretch a metal sheet to create uniform openings. Common elements of EMF include:
- Aluminum
- Copper
- Steel
- Titanium
These strong, lightweight materials can channel conductivity along a homogeneous and continuous surface and are ideal for protecting non-metallic surfaces. Incorporating CThru Mesh™ into composite materials offers excellent aircraft lightning protection. The foil absorbs the amperage and voltage over the surface area, preventing damage to the carbon fiber and other composite materials.
Static Wicks
Static wicks can safely dissipate electrical charges back into the atmosphere. The metal devices have needles or spikes on the end and get electrically connected to the aircraft’s frame.
Static wicks are encased in a fiberglass rod and connected to the frame to insulate them from the aircraft. Since the spikes concentrate the electrical charge around them, the airplane can dissipate any built-up static electricity into the air. If lightning does strike the aircraft, the electricity will travel through the dissipater instead of the plane.
Diverter Strips
Diverter strips are plastic strips with metal buttons that fasten to the satcom systems and nose of the aircraft. These segmented lightning diverters prevent heat damage by attracting lightning’s energy and forcing it to jump the gaps through the air.
Bonding and Grounding
Bonding and grounding ensure all aircraft parts maintain a continuous electrical path. Small metal protrusions on the rear edge of the tail and wing discharge static electricity that accumulates on the aircraft. When the plane lands, grounding helps safely discharge the electricity accumulated during flight.
Aircraft Lightning Protection From CThru Metals
Aircraft lightning protection incorporates numerous technologies and design principles to help keep passengers and electrical systems safe during a lightning storm. With over 30 years of industry experience, CThru Metals is a top provider of EMF and other conductive materials that help protect aircraft from lightning strikes.
Contact us or request a quote to learn how CThru Metals can meet your aircraft lightning protection needs. You can also request a sample of our CThru Mesh® expanded metal to test its full capabilities.