Wednesday, June 22, 2011

Lighting strick on Aircraft

Lightning is a discharge of electricity between highly charged clouds, or between a charged cloud and the ground.
If an aircraft is operating in the vicinity of such clouds, a discharge may strike the aircraft.
This may happen during flight or on the ground and can result in very high voltages and currents passing through the aircraft structure.

All separate parts of an aircraft are electrically bonded together to conduct a lightning strike away from areas where damage may hazard the aircraft, eg fuel tanks or flying controls.
Metallic wires or filaments within the composite structure, allowing for conductivity, may protect composite or non-metallic structures such as wing tips and nosecones.
The use of metallic wires or filaments within nosecones radomes or dielectric panels is a design feature that will not interfere with radio and radar efficiency and effect transmissions.
Lightning strikes may have two effects on an aircraft:
• Strike damage where the discharge enters the aircraft.
• Static discharge damage after the strike.

Strike damage is usually found at the wing tips, leading edges of wings and tail unit, and at the fuselage nose.
On some aircraft types, other areas may be more likely to be struck by lightning; Information on this should be obtained from the aircraft maintenance manual.Static discharge damage is usually found at wing tips, trailing edges and antenna.
Strike damage is usually in the form of small circular holes and pinholes in the exterior skin. These may be in clusters or spread out over a wide area.Burning or discoloration, blisters or holes may accompany them on radomes and cracks in glass fibre.Static discharge damage is usually in the form of local pitting and burning at trailing edges.


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