The Federal Aviation Administration (FAA) will not certify the Boeing 777-9 until it approves a redesigned mid-seal for the aircraft’s GE Aerospace GE9X turbofan engines, an agency official told FlightGlobal.
GE Aerospace is seeking approval of the redesigned mid-seal by the end of 2026, while Boeing continues to target the first 777-9 delivery in 2027.
The clarification is significant because the seal does not need to be installed on the engines used during the aircraft’s Extended-range Twin-engine Operational Performance Standards (ETOPS) certification testing.
In September, Boeing said the FAA needed to approve GE’s certification plan for the redesigned component before allowing the 777-9 ETOPS flight-test program to proceed. GE subsequently said the aircraft could conduct those tests with the previous seal configuration.
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The latest FAA statement establishes a separate requirement for final aircraft certification: the agency must approve the redesigned GE9X mid-seal before it issues the 777-9 type certificate.
GE9X deliveries resume with new seal
GE identified a durability problem with the GE9X mid-seal earlier this year after a crack was discovered during an engine shop visit. The component connects sections of the engine and had not demonstrated the durability GE expected.
The engine manufacturer determined the root cause, redesigned the component and completed internal testing before incorporating the modification into production engines.
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GE began delivering GE9X engines equipped with the redesigned seal to Boeing during the third quarter. Chief Financial Officer Rahul Ghai said in September that the company had a high degree of confidence in the new design after completing its testing.
The company’s latest financial results provide another indication of the unusual status of those engines. GE confirmed that it delivered GE9Xs during the third quarter but will not recognize the financial impact of the shipments until the mid-seal receives certification.
GE9X deliveries had previously been paused while the manufacturer addressed the durability issue. The engine is the exclusive powerplant for the 777X family and received its original FAA type certification in September 2020.
Boeing has continued producing 777-9s while certification remains underway, and GE is supplying engines for those aircraft before regulatory approval of the new seal configuration.
The 777-9 certification program began FAA flight testing in July 2024 but has encountered several delays since then. Boeing currently expects the first aircraft to enter service in 2027, about seven years later than originally planned.
