Originally Posted by
freshgasflow
I am not an aviation professional so grateful if someone could explain things to me:
If the theory of lightning strike are true, how does it lead to electrical failure ? I thought that an aircraft aluminium or metal mesh composite effectively created an Faraday cage ?
If there were local electrical transients, would this only trip circuit breakers. which presumably could be reset quickly ?
Thank you.
Well, it's not that simple. Lightning generates very large currents. I don't know anything about the specific's of the Sukhoi electrical system, but many aircraft electrical systems are single wire, chassis ground systems like an automobile. In those, lightning generating a large current in the airframe, is the same as the lightning generating a large current within the electrical system ... with the resulting possibility of overcurrent damage to critical components. Even in electrical systems whcih do not use the airframe as a conductor, the fact that you have large current transients in the airframe, adjacent the wiring, can lead to burned insulation, induced voltage spikes within the conductors, and other effects that may result in damage to critical components. As far as breakers are concerned, they are designed to protect from excessive current flowing through the normal path of the electrical circuit. A lightning strike may not trip them, it may be causing damage on components in a way that there is no excessive current flowing through the wiring at the breaker panel.