HONG KONG (AP) — China’s ambition to challenge Boeing and Airbus with its own homegrown passenger jet is running into turbulence, with deliveries of finished aircraft likely to fall far short of its target announced for this year. The C919 jet -- a single-aisle passenger plane aiming to rival Boeing’s 737 and Airbus’ A320 – is made by state-owned aircraft manufacturer COMAC. Beijing is showcasing it as evidence of China’s technological advancement and progress in self-reliance, though it uses