Boeing’s 777X certification depends on fixing durability issues within the GE Aerospace GE9X engine. The combustor liner suffers premature wear while operating at temperatures near 2,400°F (1,315°C).
Engineers must also resolve a separate engine seal durability concern identified in early 2026. These technical hurdles have delayed the 777X service entry until 2027.
GE and Boeing report that these issues do not currently disrupt certification flight tests. The long-term reliability of the world’s largest jet engine remains critical for the widebody program’s success.