Three years after its maiden commercial flight as China’s flagship civilian airliner, the C919 is entering a pivotal maintenance phase, with jets across the series being progressively grounded for rigorous inspections. The results of these safety-focused “C-checks” are expected to play a role in convincing European aviation regulators of the aircraft’s long-term airworthiness. State-owned carrier China Southern Airlines finished the first C-check of its C919 fleet at the end of May. The process...