Boeing Resumes 777X Test Flights After Grounding in August

A Boeing 777-9, a variant of the 777X, performs a flying display at the 54th International Paris Airshow at Le Bourget Airport near Paris, France, on June 20, 2023. Benoit Tessier/Reuters

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.