14 March 2013

Engine blade-off test indoor for first time.

Certification of the Trent XWB was awarded by the European Aviation Safety Agency on 7 February following successful completion of the critical full engine blade-off test, conducted using 58 Bed at Rolls-Royce's factory in Derby, UK. This was preceded by a blade-off test using only a fan module at the company's Dahlewitz site in eastern Germany on 2/Nov/2012, which provided the "data and confidence" to move to the full engine test in the UK on 29/Nov/2012.
"It's lots of millions of dollars to do [the full engine test], and we like to make sure that we're completely confident in the successful outcome of that test before we go into it," said R-R Trent XWB Program Director Chris Young, adding that the fan module test is conducted to identify any "last-minute design tweaks" that may be required.
Conducting the full engine blade-off test inside 58 Bed threw up a host of technical challenges, as the Trent XWB has the biggest fan built by Rolls-Royce, as well as the biggest individual blades. The high energy levels involved meant the company's engineers had to be sure 58 Bed - the newest and most modern test facility on the Derby campus - was structurally capable of hosting the demonstration.
"That was the first time we've done a big fan indoors - it had always been an outdoor test before," says Young. The move inside was necessitated by the UK company's decision to decommission its outdoor test facilities at Hucknall in Nottinghamshire, UK, which had been encroached by housing estates in recent years.
"It means that we can do everything that we want to 24 hours a day and be more effective in our operations rather than just do it a few hours a day when we're not annoying the neighbours too much," says Young.
In the event all went well as the blade was released at the root and the engine ran down, and was then shut down, in the presence of representatives from Airbus and EASA.
The blade was released at the "absolute maximum, red-line N1 speed, and then we actually add a little bit of margin to make sure that we're comfortable that we have some growth capability on the engine if we ever need it in the future", says Young. "It's a very arduous test that really proves the robustness and overall capability of the engine. We effectively do it at a higher speed than would ever occur in a service environment. The good news is it went very well and delivered all of the evidence that we needed for certification," he adds.

The blade-off test involved the baseline 84,000lb-thrust Trent XWB-84 for the ­A350-900. The more powerful, 97,000lb-rated XWB-97 in development for the stretched A350-1000 will require another test as it features stronger, heavier fan blades which rotate at a higher speed.
"At the minimum, we'll do a full-fan rig test," says Young.
Endurance tests.
Among the final certification tests performed for the XWB-84 was a second 150h endurance test to clear modifications designed to provide higher turbine temperature margins to extend service life. "The low-pressure turbine rotor dynamics was one last test that we had to do, again successfully completed," says Young.
Based on the article “All eyes on XWB” published in FlightGlobal

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