Thousands of lightning strikes per minute. When lightning strikes a moving aircraft, it may not cause any damage or cause great damage. The date of the last accident caused by lightning occurred in 1988 according to the records. In the following years, the investigation of the effects of lightning on airplanes together with technological developments and taking measures in this direction led to the development of effective protection techniques. Airplanes are often struck by lightning as they travel through the clouds. Lightning strikes can also be triggered when airplanes travel in different charged areas. An aircraft subject to lightning is part of the charge transfer line between electrically opposed charge-loaded zones (eg cloud and ground or cloud and another cloud). First, the lightning contacts the pointed areas of the aircraft, such as the front or wing tip. In the vicinity of the point where lightning contacts the aircraft surface, a flare may occur due to the ionization of molecules in the air. The electrically charged particles (moving along the lightning line) travel along the conductive outer surface of the aircraft and emerge from another pointed area of the aircraft (eg, the tail).
Aluminum structures with high electrical conductivity have been very much preferred in the past for aircraft body parts. Nowadays, composite materials consisting of a combination of materials of different structure can be used in the hulls of aircraft. The conductivity of these materials is generally lower than that of aluminum materials. Aircraft parts made of composite materials are coated with highly conductive materials to transfer electrically charged particles to the outer surface of the aircraft in case of lightning. When the plane is struck by lightning, sparks that occur where it encounters a crash may cause melting or burning in some areas of the aircraft. The damage caused by lightning on the fuselage is usually no deeper than 1 mm. The outer cladding of aircraft is made of thick material (mostly metal) to prevent damage to such conditions.
Lightning can cause deformation and fragmentation of parts with low electrical conductivity. The most important damage to the aircraft is the damage to the fuel systems. If a spark occurs near the fuel system when lightning strikes the aircraft, the fuel vapor of the aircraft may ignite. When lightning passes through the connections, which usually hold different parts of the aircraft together and are usually insulating, it may cause sparking at these points. Therefore, fuel tanks and ports of aircraft are designed to prevent spark formation.
Since today’s technology is controlled by computer systems from flight control systems to engines, lightning damage to aircraft electrical systems can pose a great danger to flight safety. It may cause electrical voltage fluctuations in current equipment or electrical cables running on the fuselage surface of the aircraft. In order to prevent lightning damage to the electrical systems, the cable harnesses are covered with robust protective materials. In addition, in order to discharge the static charge accumulated in the aircraft, that is to discharge it, special structures called static discharger are used which form bumps on the wing ends and behind them.