composite materials, plastic type structure composite materials, plastic type structure that is backed to form constituent parts of the aircraft, more constituent parts of the aircraft, more than constituent parts of the aircraft, more than the boeing 787 but it is more more than the boeing 787 but it is more lightweight than metal is used previously, more durable and less susceptible to coercion in the way that metal susceptible to coercion in the way that metal is so all in all, it is positive that metal is so all in all, it is positive from the point of view of efficiency positive from the point of view of efficiency and fuel burn and that is why it efficiency and fuel burn and that is why it is efficiency and fuel burn and that is why it is becoming increasingly used but as why it is becoming increasingly used but as we why it is becoming increasingly used but as we know, plastic burns in a different but as we know, plastic burns in a different way to metal and