Boeing said Monday that it has grounded its fleet of 777X test aircraft for inspections following discovery over the weekend of a failed component connected to the jet’s engine.
After one of the 777X test airplanes landed Friday in Hawaii, maintenance mechanics found damage in a structural part that links the engine and the airframe.
Inspections of the two other active 777X test planes found cracks in the same structure, according to a report in The Air Current, an online aviation news service that first reported the details Monday.
In a statement, Boeing said only that the damage on the plane in Hawaii was discovered “during scheduled maintenance” and that it is inspecting the other 777X test planes.
“Our team is replacing the part … and will resume flight testing when ready.”
The affected part is called a “thrust link,” a heavy titanium component. The thrust of the engine is transferred to the airframe through this link between the engine and where it is mounted on a pylon beneath the wings.
The thrust link is not part of the GE-9X engine that powers the airplane, but a Boeing-designed connector to the engine. This specific design is unique to the 777X.
The GE-9X is an enormous engine, weighing about 11 tons and featuring a front fan that’s more than 11 feet in diameter.
Each engine has two of these thrust links for redundancy, in case one were to fail.
The news is another setback for the 777X program. The jet was launched in 2013 and first flew in 2020, but certification of the jet by the Federal Aviation Administration has been repeatedly delayed.
The FAA last month finally cleared Boeing to begin test flights for credit. Now those flights are paused.
Boeing said it has informed the FAA and is sharing information with prospective 777X customers. Boeing recently said it aims to deliver the first 777X in 2025, five years behind schedule. But customers, including Gulf carrier Emirates, have already said before this latest problem that they don’t expect it until mid-2026.
In a note to investors Monday, Ken Herbert, a financial analyst with RBC Capital Markets, wrote that “Even if flight testing resumes in the near term, the current grounding could limit investor confidence in the [777X] program.”
In the spring of 2022, having built — in addition to four test jets — about 20 777Xs for customers (some are now stored nose to tail on an unused runway in Everett), Boeing paused 777X production until certification was closer. It resumed 777X production only late last year.
Herbert said if the new discovery causes production to halt again, that will slow Boeing’s cash flow recovery.
Of the four 777X test planes, only three are actively flying now. One is the jet in Hawaii; another is parked at Boeing Field; the third is in Everett.
