The first flight of a engine kicks off a busy year for the lone engine supplier for the twin-widebody as a raft of tests and design choices have to be accomplished to keep the program on track.
The test flight on an Airbustook place in Toulouse on Feb. 18, with the flight lasting more than five hours, reaching an altitude of 43,000 ft. and speeds of up to Mach 0.9, according to Airbus. The Trent XWB was the inner-left engine, with the other powerplants .
Ground testing of the engine began in June 2010.and Airbus were hoping to begin flight trials last year, but decided to make fixes to the engine after discovering a flaw to ensure the most production representative standard available could be flow, even at the cost of a few months of schedule delay; since then, the overall A350 program schedule has been adjusted to delay entry into service to 2014. The schedule adjustment also means Rolls-Royce will likely be able to introduce some weight savings at the get-go for production aircraft, rather than phasing them in later.
Around 175 flight hours are to be logged during the trial phase running around seven months. Airbus notes thenacelle and thrust reverser are also being put through their paces.
“The A350XWB’s engine performed excellently during its first flight-test, just as we expected,” says Charles Champion, Airbus Executive Vice President of Engineering said in a statement.
Since the beginning of ground testing, Rolls-Royce has already used some positive news on performance margins in some areas to trade in for better fuel burn numbers, with more underway. The engine maker is still seeing sufficient surge compressor margin to garner another reduction in specific fuel consumption. Rolls-Royce, last year, already traded some of the surge margin to boost 0.25% of the SFC improvement, but believes it can take a bit more for the additional 0.1 percentage point, according to the powerplant’s program director Chris Young.
Eight engines have been used for various phases of ground testing and clocking more than 1,500 test hours so far. The number of test hours should also start increasing more rapidly as the focus shifts to validating engine maturity and fewer changes are made to build standard. Cyclic testing using engine 20003 began in late December, contributing to the ramp-up in hours.
Among the key test milestones ahead is ingestion of a large, 4 lb. bird, with the goal of completing the milestone before April. Fan-blade-off testing should take place mid-year.
Furthermore, a second round of endurance testing is planned to start soon as well. The first ran for 150 hours. It was during these trials that the need for a flying seal fix was identified, which led to the original delay in A380/TrentXWB flight trials.
Moreover, Rolls is working to lock-in the exact configuration around mid-year for the engine to power the largest member of the A350 family, the A350-1000. The -1000 changes are requiring Rolls to deliver a 97,000 lb. thrust powerplant, rather than just 93,000 lb., with a target of maintaining the same specific fuel consumption level. Broadly, the engine will feature increased flow through the fan system and a larger core incorporating tip clearance control, enhanced materials, and advanced coatings.
The exact definition will be set around mid-year, after which detailed design will commence. The A350 schedule change, with entry into service moved to 2017 from 2015, means “a greater choice of potential technologies” to use for the TrentXWB-97, Young says. It also should reduce the level of risk involved with some of the technologies.
Rolls is drawing on a number of technology activities to help validate what may be feasible on its most powerful turbofan. They include a TrentXWB-84 engine being converted to test some of the -97 technologies, the two shaft E3E test engine being run in Germany to explore tip clearance, and the three-shaft Environmental Friendly Engine running in Bristol where turbine blade cooling is being looked at closely.
Some programmatic decisions remain to be made, including how many test engines will be built – the initial assumption is five – and whether another flight test campaign will be required. That could involve either the A380 (being used for the core Trent XWB program) or an A350.
Rolls plans to start building the first TrentXWB-97 test engine in early 2014 to allow first engine runs in mid-2014, with first flight on an A350-1000 in the first half of 2016.
Production of the engines is likely to happen in the same line as the other Trent XWBs.