The signal is clear. In the first quarter of this year, just three C919 aircraft were delivered – two to China Southern Airlines and one to Air China. For a Chinese programme expected to deliver more than 30 of these home-grown narrowbody airliners this year, the gap between ambition and reality has opened up quickly.

Commercial Aircraft Corporation of China (Comac) delivered 15 C919s last year, far short of the target of 75 set before supply disruptions forced a reset. Even the modest reported goal of at least 28 this year now looks stretched. Since late 2022, Comac has delivered just 35 C919s.

Comac’s position has been consistent: quality will not be sacrificed for speed. In aviation, that instinct is sound. But the slowdown points to something deeper: a structural constraint at the heart of China’s narrowbody airliner ambitions. And that constraint lies in the engine.

The C919 depends on the LEAP-1C engine, produced by CFM International, a joint venture between GE Aerospace and Safran. Assembly in Shanghai has found its rhythm. Airframes no longer seem to be the problem. The bottleneck appears to emerge after completion, when finished aircraft wait for engines and key components that arrive more slowly than expected.

This is more than a temporary squeeze. Shortages in high-performance turbine components have forced suppliers to prioritise established customers such as Boeing and Airbus while new entrants wait. More importantly, it exposes how much of the C919 still depends on external inputs at its most critical point. Engines define performance, reliability and maintenance ecosystems. When access to them tightens, whether due to production limits or political decisions, everything else slows down.

That vulnerability became clear last year, when US export licensing restrictions disrupted engine deliveries and forced Comac to revise output. What looked like an operational delay revealed structural exposure. As aviation consultants have pointed out, the challenge is not simply how many aircraft can be built, but whether the supply chain behind them can be relied upon.