In Flight Intl a month or two back they had an article about the A350 and IIRC they said that with the use of composites etc etc in the airframe they would reduce the A350s weight by x compared to the a330. But because of something to do with the new generation engines being heavier or needing a heavier pylon, actual weight reduction would be less than x by a certain amount (IIRC it was maybe 1 or 2 metric tons per plane).
In AWST this week, they have a whole article (well, actually more like an advert) on the 787 suppliers and the GenX engine etc is supposed to save 350kg in weight vs a similar engine without composite casing, blades etc.
So whats with the A350 engines or the pylon (supposedly the same basic engine as the 787s but with bleed air) being heavy. Is it all related to the associated bleed air systems?? Or is there something else I am missing or misunderstood?
(Interestingly, if I read the AWST article correctly, the 20% fuel savings that the 787 will have over present planes (presumably the 767) is something like 13% from composite airframe structure, 3% from bleedless systems, 3% from improved aerodynamics.)