SEATTLE—Boeing resumed testing for its long-delayed 777X widebody jet on Thursday, with the first flight since the planemaker grounded the test fleet in August due to the failure of a key engine mounting structure.
The grounding came just five weeks after it had started certification flights for the 777-9 with officials from the U.S. aviation regulator onboard.
Federal Aviation Administration staff were not on board for Thursday’s flight, according to the company.
The 777X is the successor to Boeing’s 777, one of the most commercially successful long-haul airliners. The company initially planned to deliver the first 777X to launch customer Qatar Airways in 2020….