Bond-rating agency Moody's says Chicago's pension woes could become such a drag that they throttle the growth of the city's main economic engine, O'Hare International Airport. "While the airport is largely immune from the pension funding issues affecting other Chicago credits, Moody's expects that steps to remedy pension funding issues will reduce the trajectory of long-term economic growth, which will cause the airport to see weaker origination and destination passenger growth than its international gateway peers," the ratings agency said yesterday even as it maintained a healthy A2 bond rating for the airport, which is in the process of issuing some refinancing bonds. The news about Chicago's pension funding problems has been gloomy for a long time, and Moody's has been more bearish than most on the city's prospects. It was the first to downgrade city debt to junk status two years ago.