Spirit AeroSystems, a key supplier to US planemaker Boeing, warned on Tuesday there was “substantial doubt” that the company would be able to continue as a going concern.

Aircraft-parts supplier Spirit AeroSystems Holdings Inc. on Tuesday said that there was “substantial doubt” about its ability to keep running as a “going concern,” as losses, debt, and difficulties at jet maker Boeing Co.

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