both the General Electric GEnx-1B and Rolls Royce Trent 1000 engines are rumoured to have missed specific fuel consumption targets by 2-3% and 3-4% respectively.
a rumoured design change to the Trent 1000 low-pressure turbine could require Dreamliner One to switch to GEnx engines.
Is Trent XWB based on Trent 1000?
If yes, do Trent 1000 problems afflict the delivery date or range of Airbus 350?