A new setback for Boeing and its upcoming – but heavily delayed – 777X widebody flagship has emerged, as Boeing admitted late on Monday that it had suspended all flight tests on the 777X after it found damage in a structure that joins the aircraft wing with the engine.The discovery was made during post-flight inspections of the third test aircraft, WH003, following its return to Kailua-Kona, Hawaii, from a 5 hour 31 minutes certification test flight over the Pacific.The company said it discovered the damage to the custom part, which it described as between the engine and the aircraft structure, during scheduled maintenance. It has since grounded the three other 777-9 airplanes in its test fleet. No other flight testing was scheduled for the other aircraft, Boeing said.“Our team is replacing the part and capturing any learnings from the component and will resume flight testing when ready,” Boeing said in a statement. It said it has informed the Federal Aviation Administration and its customers, which have ordered 481 of the 777X, according to the company’s website.It’s not immediately clear whether the grounding and issue would impact certification and delivery of the new wide-body jetliners, which are scheduled for 2025, around five years behind schedule. Boeing started a flight test campaign of the aircraft with the FAA in July, a major milestone. The news, first reported by The Air Current, comes as Boeing’s leaders, including new CEO Kelly Ortberg, are trying to strengthen the company’s safety culture following high-profile incidents as a result of shortcomings in the production of Boeing aircraft.During Boeing’s Q2 earnings call on July 31, former President and CEO Dave Calhoun announced that the 777-9s had completed over 1,200 flights and accumulated 3,500 flight hours (FH) across various conditions. Brian West, Boeing’s CFO and executive vice-president of finance, reaffirmed the company’s commitment to following FAA guidelines, with plans to deliver the first 777X to a customer in 2025.Gulf carriers account for two-thirds of the total orders placed for the Boeing 777X. Qatar Airways is set to take its first delivery of a 777X in the first quarter of 2026. Boeing expect the -9 variant of the 777X, which has secured the most orders, to be around 12% more fuel efficient than the existing 777-300ER which is in service with multiple major airlines worldwide. Once the 777X does finally enter service, the aircraft will become the world’s largest twin-engine airliner.Meanwhile, aviation regulators in the United States have ordered airlines to carry out inspections of hundreds of Boeing 787 Dreamliners after a sudden mid-air dive during a flight in March injured dozens of passengers.The Federal Aviation Administration (FAA) said on Monday that the captain’s and first officer’s seats on certain 787-8, 787-9 and 787-10 aeroplanes should be inspected “for missing or cracked rocker switch caps and for cracked or non-functional switch cover assemblies” within 30 days.“Operators must also perform any necessary corrective actions,” the FAA said in a statement.The FAA directive affects 158 US-registered aeroplanes and 737 aeroplanes worldwide, the regulator said.The airworthiness directive (AD) comes after Chile’s aviation authority said earlier this year that preliminary inquiries into the March 11 incident showed that the captain’s seat experienced an “involuntary movement forward” during the flight.Some 50 passengers were injured when LATAM Flight 800 suddenly plunged 400 feet (120 metres) while en route to Auckland, New Zealand from Sydney, Australia.In its directive, the FAA said the “uncommanded horizontal movement” of the captain’s and first officer’s seats during LATAM Flight 800 had “caused the control column input to disconnect the auto-pilot, resulting in a rapid descent until the First Officer took control of the flight”.The FAA received four additional reports of the problem from Boeing following the incident, the most recent of which was in June, the regulator said.“Uncommanded horizontal movement of an occupied seat can cause in-flight upset from unintended and abrupt flight control inputs, which could result in a rapid descent of the airplane and serious injury to passengers and crew,” the FAA said.“The FAA is issuing this AD to address the unsafe condition on these products.”Boeing said in a statement that it fully supports the directive, “which makes mandatory a supplier’s guidance to 787 operators.” The directive is the latest in a series of incidents to draw attention to safety issues at Boeing.Boeing last month finalised a deal to plead guilty to fraud after US prosecutors concluded that the company violated a deferred prosecution agreement over two fatal crashes of the 737 Max in 2018 and 2019.The Arlington, Virginia-based aircraft giant is also facing a separate criminal investigation into a January incident during which a 737 Max operated by Alaska Airlines lost part of its fuselage mid-flight.The author is an aviation analyst. X handle: @AlexInAir