(Reuters) - U.S. supplier Spirit AeroSystems ( SPR ) said on Tuesday in a quarterly filing that substantial doubt exists about the company's ability to continue as a going concern.

Last month, the company said was burning through dwindling cash reserves, as a strike by Boeing's U.S. factory workers hammered the finances of its biggest supplier.

Spirit Aero said that it had drawn down an entire $350 million bridge loan set up when Boeing agreed to acquire the supplier in June, confirming an earlier report from Reuters.