Rolls-Royce is preparing a prototype demonstration for the higher-thrust Trent XWB-97 engine which will be used on the A350-1000.
The basic XWB-84 engine for the A350-900 has been newly certificated. It is capable of delivering 84,000lb of thrust and the certification also covers the XWB-75 and -79 versions for the smaller A350-800.
But the XWB-97 powerplant for the A350-1000 - put forward as part of the larger type's redesign in 2011 - is undergoing a separate development and approval process.
The prototype will be built from an XWB-84 engine platform with additional turbine technology fitted, says Trent XWB programme director Chris Young.
He says this will allow the manufacturer to "run it as close as possible to [more demanding] conditions and temperatures".
Rolls-Royce intends to construct two demonstrators this year, with initial build about the begin. Young expects the first runs will start around the middle of 2013.
It held a preliminary design review for the XWB-97 powerplant in January. Young says this allows the manufacturer to move into detailed design of individual components, and work on the machining definition and initial casting to "get the prototype engine in place".
The XWB-97's basic dimensions - such as the fan size, mounting points and interfaces - remain the same as those for the XWB-84.
"But we take more flow through the fan, by spinning the fan faster, and changing some aerodynamics in the fan system," says Young. The changes include an inflected annulus and a larger core, and technical changes to extract more power. Technological advancements will include shroudless high-pressure turbine blades and an adaptive cooling system.
Young points out that the XWB-84 engine has already been run at thrusts "well in excess" of 100,000lb, and that the growth is "more about restoring margins than airflow".
The design review has confirmed that the higher-thrust engine will have 80% commonality with the XWB-84 in terms of line-replaceable units, with only fuel pumps and metering systems not retained.
Rolls-Royce has completed the latest build of its EFE technology platform in Bristol, which is based on the Trent 1000 core, and has carried out tests of high-temperature thermal paint. Young says that using a platform "as representative as possible" for the XWB-97 prototype will help with "risk reduction" during the powerplant's development.