A Boeing 777X aircraft performs a demonstration flight at the 2021 Dubai Airshow in the Gulf emirate on Nov 14, 2021. (GIUSEPPE CACACE / AFP)

WASHINGTON - Boeing Co said on Thursday it had resumed flight testing of its 777X jets after an inspection in October found an engine issue.

GE said last month it was reviewing a technical issue that occurred during GE9X post-certification engineering testing of the plane, and had decided with Boeing to remove the engine and send it to a test facility in Ohio for engineering test runs.

The 777X, also known as the 777-9, is a larger version of the 777 wide-body jet and has been in development since 2013

The 777X, also known as the 777-9, is a larger version of the 777 wide-body jet and has been in development since 2013.

Boeing in April said it was halting production of the 777X through 2023 and confirmed a delay in handing over the first 777X jet to 2025 from the previous target of late 2023, but said it remained confident in the program.

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The Federal Aviation Administration warned Boeing in a March 21 letter that existing certification schedules for the 737 MAX 10 and 777X were "outdated and no longer reflect the program activities."

Certification is needed before Boeing can begin deliveries.

In May 2021, the FAA told Boeing that, realistically, it would not certify the 777X until mid- to late 2023 and rejected a request by Boeing to clear a certification hurdle, citing numerous concerns about lack of data and lack of a preliminary safety assessment. The 777X had previously been expected to be released for use in June 2020.

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Congress approved a sweeping certification reform bill in late 2020 after two fatal Boeing 737 MAX crashes that had added new requirements to getting aircraft approved.

Boeing Chief Executive Dave Calhoun said in April that it is "definitely a more rigorous process that we're all going through" to get airplanes certified.