I often hear of comments on this forum of people saying that a certain aircraft has bad performance because it is getting old when new aircraft of the same model are still coming off the production line. The best examples concern A340 "classics" and the B767 family. So here is my question : do aircraft loose performance with age. I can imagine a 1% change during an aircrafts' life but surely no more? Do this really justify replacing them with very expensive newer aircraft?
Thanks to all