Boeing (BOE, Washington National) has grounded its B777-9 testbed fleet after a routine post-flight inspection revealed the failure of a piece of the structure that mounts the engine to the aircraft, The Air Current reported on August 19 and the manufacturer subsequently confirmed to ch-aviation.
“During scheduled maintenance, we identified a component that did not perform as designed. Our team is replacing the part and capturing any learnings from the component and will resume flight testing when ready,” Boeing told ch-aviation.
The impacted part is a structural component between the engine and the central structure, custom-made for the B777-9. Each engine has two parts of this component. The US Federal Aviation Administration (FAA) said Boeing had informed it of the discovery of a damaged component following a flight test last week, adding that the manufacturer was taking steps to assess the problem.
The Air Current reported that the issue was discovered on N779XY (msn 65799), Boeing’s third test aircraft. Subsequent inspections on other test aircraft of the type revealed cracks in the thrust link structure.
ADS-B data shows N779XY last operated a five-hour flight in Hawaii, departing and landing at Kona. No near-term flight tests have been planned on the other testbed widebodies, which have scheduled maintenance and layup activities, ch-aviation understands.
Boeing received the type inspection authorisation (TIA) for the B777-9 in July 2024 and began certification flight testing with FAA personnel onboard the aircraft, the company revealed in its second-quarter investors call. The manufacturer still expects the first delivery of the type to take place in 2025.
Boeing has received orders for 383 B777-9s, with Emirates being the largest customer (expecting 170 aircraft of the type). Other customers include ANA - All Nippon Airways, Air India, British Airways, Cathay Pacific, Ethiopian Airlines, Etihad Airways, Lufthansa, Qatar Airways, and Singapore Airlines.
