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Load testing of Boeing 777X plane resulted in fuselage failure

Near the end of a stress test, the exterior of a plane 777X ruptured.

EVERETT, Wash. — A depressurization of the aft fuselage of a 777X static test airplane, which is a test plane used for structural certification testing, occurred during testing, according to a statement from Boeing. 

The issue occurred in the final minutes of the test at approximately 99 percent of final test loads, according to the statement. The test involved bending the wings of the plane "to a level far beyond anything expected in commercial service," the statement says. 

Boeing said the results will "not have a significant impact" on design or the company's preparations for a first flight. The first delivery of the 777X is expected in early 2021. 

The Boeing 777X is still in development and is the first airliner with folding wingtips. The outside 12 feet of each wing can fold up, allowing the jet to get into airport gates. The plane’s overall wingspan is 235 feet.

The details were kept secret until The Seattle Times published a photo that showed the extent of the damage from the test.

Near the end of the test, the plane's wings were bent more than 28 feet - past the normal deflection of 9 feet, a source told The Times. While the wings were bent up, the fuselage was pulled down while the plane's interior was pressurized beyond normal. The test was simulating a force of 3.75G, The Times reports. 

The result: the plane's exterior ruptured. 

"As we shared on our Oct. 23 earnings call, our root cause assessment continues, and we are pleased with the progress we are making as we complete our detailed analysis. What we’ve seen to date reinforces our prior assessment that this will not have a significant impact on the design or our preparations for first flight. We do not see any impact from the test on the overall program schedule," Boeing said in the statement. 

A source within the Federal Aviation Administration confirmed to the Times that because the failure occurred so far along during the test, it won't have much of an impact on development.