Boeing completed the ultimate limit-load test on the static test 787 airframe, ZY997, at Everett on March 28. The test – officially dubbed Condition 18b - evaluates the ability of the wing-body structure to sustain loads equal to 150% design limit load - or the most extreme forces ever expected to be seen in service, and its clearance marks the passing of a significant hurdle on the way to FAA certification.
787's amazing swallow-like wing deflection at 150% of design limit load. (Boeing)
During the test, which occurred with 14.9 psi fuselage pressure, the wingtips deflected upwards by approximately 25 ft. The test, which did not continue until the wings failed, was also a key evaluation of the strengthened side-of-body modification which in June last year caused a six-month delay to the start of 787 flight tests. The deflection of the higher-aspect ratio composite wing was greater than that of the metallic 777 wing, the last major primary structure to undergo “wing ultimate up-bending” tests in Boeing’s sprawling Everett site more than 15 years ago. The 777 wing failed at 154%, having deflected 24 ft.
Internally Boeing is hailing the test as a major success, though externally the company is sounding a note of caution. “The initial results of the ultimate-load test are positive. More extensive analysis and review are required before the test can be deemed a success,” says Boeing.
With static test complete, all eyes will be back to the flight test fleet and the hoped-for granting of FAA type inspection authorization which will clear the way for the official start of certification. The completion of static work is important as an enabler for testing of the extreme edges of the flight envelope during certification.
The milestone inside the factory coincides with events on the flight line and at the engine manufacturers, both of which are testing upgrades to their respective 787 engines which they say are on track to get within 1% of Boeing’s original fuel burn performance specifications.
The first General Electric GEnx-1B powered 787, ZA005, has rolled out to the flight line in readiness for pre-flight tests in April. The aircraft, along with sistership ZA006, will be powered by the ‘Block 4’ variant of the engine. However, most production aircraft will be delivered with GE’s enhanced GEnx-1B “performance improvement package” (PIP 1) which is centered on a revised turbine module to help reduce fuel burn.
The first new turbine is now on test at GE’s Evendale, Ohio facility and indicating positive results, according to the engine maker. The initial production PIP1 standard GEnx-1B engines will be delivered to Boeing by the end of 2010, meaning that the first 787s with the upgraded engines could be delivered in the March to May 2011 timeframe says GE. However the first GEnx-1B 787 will enter service (aircraft No.17 to Royal Air Maroc) with Block 4 configuration engines.
Flight tests of Rolls-Royce's Package B Trent 1000 variant are getting underway in Alaska. (Rolls-Royce)
Rolls-Royce is now flight testing the first Trent 1000 built to the improved ‘Package B’ standard which is designed to bring performance to within 1% of Boeing’s original specification. The first Package B engine is currently installed on the company’s 747-200 flying testbed and performing tests in Alaska in preparation for the installation of upgraded engines on 787 ZA004. In all, Rolls has run three Package B performance engines and says all are showing fuel burn performance in line with expectations. To read more about the engine programs check out this week’s edition of AW&ST.