Airbus expects to finalise the A350 XWB's "aero-lines" in July as it heads for the detail definition freeze of the baseline -900 version at the end of the year.
However, the airframer says it still has two years to refine the wing design of its largest model, the -1000, which will be the last A350 variant to enter production.
"This year we've had a lot of work in front of us," says A350 programme chief Didier Evrard. There will be final freeze of the details of all the aero-lines in July." He adds that "the important milestone of the detail definition freeze will be reached at the end of the year".
Airbus's three-pronged A350 family development plan calls for each of the models to enter service around a year apart, beginning with the A350-900 in 2013 and followed by the smaller -800 and larger -1000.
Evrard says that the detail definition freeze for the -800 and -1000 variants will follow this "left to right plan" and occur one and two years after the -900's respectively. "Because of the family concept, the scope of this milestone for the -900 is much more important as it is the first version," he says.
At 295t, the -1000's maximum take-off weight will be 20% greater than the -800's and Evrard says while there are currently no plans to change the wing design significantly, "we have another two years" before the design will be finalised.
He says that while the structure will be optimised for each variant, "it is not intended to change the wing aero-lines, at least for now". As currently proposed the -1000 "will have a similar wing" to the smaller models, he says, although "there will be detail differences, for example to the high-lift system and the pylon".
In the meatime, Airbus will hold the third A350 programme progress review (PPR3) in June in Madrid with customers. PPR2 was held in September last year in Bordeaux with 40 airlines.