Boeing has grounded its fleet of 777X test aircraft following the discovery of a cracked thrust link, a structural component connecting the engine to the airframe, during routine maintenance. This issue, affecting multiple test aircraft, has led to a halt in flight tests and poses potential further delays to the already delayed 777X program, initially expected to enter service in 2020 but now projected for 2025 or later. Boeing is replacing the faulty parts and will resume testing once the replacements are verified. This setback adds to Boeing's ongoing challenges, including previous quality control issues and delayed certifications by the FAA, with major customers like Emirates expressing doubts about receiving their orders by the revised timelines. Boeing has informed the FAA and customers about the issue and is working to ensure safety and compliance before resuming operations.