Rolls-Royce (R-R) and Airbus have completed a critical design review (CDR) for the Trent XWB-97 engine destined for the A350-1000.
The XWB-97 is designed to generate the higher thrust needed by the A350-1000 without any increases to the size of the nacelle used on the A350-800/900, and without impacting the specific fuel consumption or on-wing life of the engine. To solve this conundrum, the larger engine incorporates a higher flow-capacity fan to pump more air, a larger core to increase flow and higher-capability turbines to extract power for the fan.
Prototype demonstrations to prove key technology for these improvements also are underway at INTA (the Spanish space agency) in Spain, using a modified XWB-84, and the design groups at the CDR meeting viewed data from these tests as part of development review.
“Some key milestones are coming,” says Trent XWB’s program director Chris Young. Development activity is rapidly accelerating on the new engine as the first Trent XWB continues in flight testing. “We still have a lot of people working on the 84K [XWB-84], but now we have passed the crossover point where there are more people working on the XWB-97.”
Prior to the joint review with Airbus last week, R-R had “just completed the CDR [at R-R] for the 97K engine. It’s a really important milestone because it is the one that says you are good to start machining and to start releasing the drawings to get into final manufacturing. After that is when parts start coming in to stores at the end of the year and early next year. That clears the way for the start of assembly and first test in the middle of next year,” Young explains.
Following the completion of a preliminary design review for the XWB-97 in January, Young says “there is real raw material coming together for forgings and castings.” These include the completion of rough machining of the first variable stator vanes, initial machining of the intermediate pressure (IP) compressor sixth-stage disc, and trials of the linear friction stir weld process on the IP compressor first-stage blisk. The cone for stage six of the high-pressure (HP) compressor rear drum assembly and other core parts of the first engine are also underway.
Baseline development engine ESN20001 has begun runs of XWB-97 development materials and tip clearance control systems. Tests will evaluate new shroudless HP turbine blades and seal segments. “So we are trying to prove that when the turbine runs into the ceramic seal it will last forever, even though it has had a rub,” says Young.
A second run early in 2014 will include tests of a “full standard of shroudless turbine with tip clearance and cooling,” he adds.
The engine is scheduled to be flight-tested on the Airbus A380 flying testbed at the end of 2015, and will power the A350-1000 for its maiden flight in 2016. Entry-into-service is targeted for mid-2017. Meanwhile, the XWB-84 version continues in flight test on the A350-900 prototype, which it has powered without incident since the first flight on June 14.