Airbus is to confirm plans at the Paris air show for a significant redesign of the A350-1000 in an effort to increase the largest XWB variant's competitiveness with the rival Boeing 777-300ER.
Flightglobal understands that the update centres on engine, wing and weight changes to boost payload-range.
The 350-seat A350-1000 is the last of the three main XWB variants in the initial development plan, with service entry officially slated for the end of 2015.
It has been undergoing a major design review as Airbus engineers work to finalise the aircraft's configuration and performance as part of the definition effort. This phase of development is due to conclude with the "detailed definition freeze" at the end of 2011.
Key A350 customers are being briefed by Airbus on the revamped design ahead of the Paris air show, when the airframer is due to provide a public update.
Sources familiar with the situation indicate that the aircraft has undergone some significant changes, central to which is the acceptance by sole engine supplier Rolls-Royce to redesign the version of the Trent XWB that will power the A350-1000.
Originally slated to be a slightly modified version of the A350-800/900's 75,000-84,000lb thrust (374kN) Trent XWB variant rated at 93,000lb thrust, Flightglobal understands that the engine will now incorporate a revised core to deliver a significant boost in thrust towards 98,000lb.
The option of enlarging the fan is understood to be problematic due to wing-to-ground clearance issues.
"Rolls has accepted that it must increase the engine thrust," said Akbar Al Baker, chief executive of A350-1000 launch customer Qatar Airways.
The original plan for the A350 wing was for it to be common wing across all three variants, with changes on the -1000 limited to trailing edge extension of around 400mm (16in). Airbus is is now understood to have decided to enlarge the wing further as part of the wider redesign.
In parallel, Airbus has raised the -1000's maximum take-off weight above the current 298t, which is understood to have delivered a 500nm (925km) boost in payload-range to an estimated 8,500nm. The revisions are believed to have pushed planned service entry into 2016. "We'd like increased take-off weight and increased range," said Al Baker.
Sized to compete with the 777-300ER, there have been pressure from some quarters - notably Emirates chief Tim Clark - for Airbus to boost the -1000's payload-range to make it a better proposition.
While these changes look to address that, former International Lease Finance chief Steve Udvar-Hazy, who previously pushed Airbus to redesign the original A350 five years ago, does not yet view the A350-1000 as a genuine 777-300ER rival. "There is some overlap, but I see it more as a replacement for the operators of the Airbus A340," he said.
Airbus currently holds orders for 75 A350-1000s from four customers - Qatar Airways and Emirates each with 20, Etihad Airways with 25 and Asiana with 10. Neither Airbus nor Rolls-Royce are commenting ahead of the air show.