Forget the 737 MAX crisis – even the 777X program has not been without its challenges. In September 2019, it was widely reported that a cargo door on a Boeing 777X static test plane “blew out” during a ground stress test at the manufacturer’s Everett, Washington, plant. Keeping silent about the details of the incident, Boeing confirmed that the fuselage of the test aircraft suffered a high-pressure rupture just as it approached its ultimate load required to certify the jet.

It was certainly not the outcome that Boeing engineers expected when they put the new 777X airframe on a final structural strength test on September 5, 2019. First to report the news, The Seattle Times wrote at the time that a cargo door on a 777X test aircraft had failed during the high-pressure stress test, exploding outwards. Because of the incident, the manufacturer was forced to suspend load testing of the new model.

“During final load testing on the 777X static test airplane, the team encountered an issue that required suspension of the test,” the company’s spokesperson Paul Bergman said in a statement confirming the news back in September, as quoted by the newspaper.

Since then, Boeing has kept silent on the details of the failed test and what actually occurred at the facility. But a new report by The Seattle Times on November 27, 2019, revealed additional information on the incident, rectifying certain crucial details reported previously.

The final load trial of the 777X static test airplane (built for ground testing only) involved flexing the aircraft’s wings beyond the expected level during normal commercial flights. Just as the test approached its target stress level, a failure occurred.

“A testing issue occurred during the final minutes of the test, at approximately 99 percent of the final test loads, and involved a depressurization of the aft fuselage,” Boeing said in a statement, as quoted by Reuters.

However, according to the The Seattle Times, the door that blew out and fell to the factory floor was, in fact, a passenger door (not cargo, as reported prior) and was a secondary impact of the initial rupture that tore through the fuselage, located far below the door.

Photos of the 777X test that the newspaper said it obtained show the fuselage skin of the test aircraft ripped apart just behind the wing, indicating that the extent of the damage to the test aircraft was greater than previously suggested.

Boeing has previously said that the incident will not cause delays in the 777X program schedule. In any case, the failure of the test comes at a time when the program is already experiencing delays due to problems in the development of the massive GE9X engine purpose-designed for the new jet.

The plane maker also said that it does not see any significant impact on the design of the jet or preparations for the first flight. Boeing currently targets first flight of the 777X in early 2020 and the first airplane to be delivered to an airline in 2021.

Earlier in November, several media reports indicated that GE Aviation has managed to fix the issue with its  GE9X, involving the engine’s stator vanes, and is in the final stages of certification testing, which would pave the way for the 777X to eventually take to the skies for its first flight test. 

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Boeing expects the “exploding door incident” to have no significant impact on the 777X design. The incident is unlikely to affect the overall test program schedule of the new widebody jet, the planemaker said in a statement on September 10, 2019.