In April, Boeing provided a $425 million advance to support Spirit's liquidity. Spirit, Wichita's largest employer with around 12,800 full-time workers, previously disclosed it has spent all of that money, as well as the entirety of a $350 million bridge loan that was set up earlier this year.

Spirit AeroSystems and Boeing are close to reaching a funding agreement that would give a cash lifeline to the struggling Boeing supplier, an industry source familiar with the matter said.

Spirit AeroSystems said on Tuesday that Boeing will pay a total of up to $350 million in advance payments to the firm, providing the struggling supplier a lifeline as it continues to burn cash after four consecutive years of losses.

"We would not be surprised to see another such arrangement be announced," a prominent Wall Street aerospace sector analyst said.

By David Shepardson and Allison Lampert (Reuters) -Spirit AeroSystems said Tuesday that planemaker Boeing will pay up to $350 million in advance payments to the firm, providing the struggling supplier a lifeline as it continues to burn cash after four consecutive years of losses.