Boeing Co has paused flight tests of its 777X jetliner while it inspects the four-aircraft fleet for cracking in a crucial structural component that connects the hulking General Electric Co engines to the plane’s wings.

The plane-maker said it discovered a damaged thrust link on a 777-9 during routine maintenance following a test flight. The component “didn’t perform as designed”, the company said in a statement. Boeing plans to replace the component and “will resume flight testing when ready”, it said.

The issue marks the latest setback to Boeing’s effort to certify its largest jetliner, which is already about five years behind schedule, after the company finally began flight tests with US regulators on board in July. The company has been embroiled in crisis since a midair blowout on one of its jets early this year threw a spotlight on its manufacturing and safety record.

“The grounding could push 777X delivery expectations to the right, and potentially into 2026,” Ken Herbert, an analyst with RBC Capital, told clients in a note on Monday. He predicted the 777X programme would likely encounter a “prolonged approval period”.

Boeing shares fell 0.9% in pre-market US trading on Tuesday. The stock has declined 31% this year. 

Boeing said it is inspecting other jets in the 777X flight test fleet for the issue. No near-term flight tests were planned for those airplanes. GE Aerospace said there is no issue with the GE9X turbofan, which is the largest and most powerful commercial jet engine ever built.

Boeing said it had notified the Federal Aviation Administration and customers of the issue on the thrust link, which is custom-designed for the 777-9, the first jet to be developed in the 777X family. 

The agency said the flight test that preceded the discovery occurred last week, confirming an earlier report by the Air Current.

  - Bloomberg