Spirit AeroSystems (NYSE:SPR) rose 3% in premarket trading after Boeing's (NYSE:BA) CEO said the potential acquisition is not delayed. "It's not being delayed, nothing's off the rails," Boeing CEO Dave Calhoun said in an interview on CNBC.

Boeing moving its inspection and rework teams to Wichita has "dramatically reduced our nonconformances," Calhoun said Wednesday.

(Reuters) -Spirit AeroSystems said Boeing would give it advance payments of $425 million and help it address issues like higher levels of inventory and lower cashflows after the U.S. aviation regulator capped the planemaker's 737 MAX production.

Boeing's (BA) issues continue to mount as the aerospace manufacturer grapples with shrinking orders, a growing backlog of orders it needs to fulfill, and more, according to its first-quarter earnings report.

The Boeing Co. has agreed to forward Wichita's Spirit AeroSystems, its biggest supplier, $425 million over the next six months to help the company with cash flow, according to a Tuesday Securities and Exchange Commission filing.

Boeing's plan to buy back supplier Spirit AeroSystems has become mired in protracted discussions over pricing for factories that make components for Airbus.

Tough questions await Boeing when it announces its results on Wednesday, including on potential CEO candidates, talks with Spirit AeroSystems and slumping 737 MAX jet output, while its quarterly report is expected to show a surge in cash-burn rate.

Boeing's attempt to buy back Spirit AeroSystems is hindered by valuation disputes of factories that supply Airbus.

Boeing is providing a $425 million advance payment to Spirit AeroSystems in an attempt to steady its embattled supplier in the short term.

The Boeing Company is advancing Spirit AeroSystems $425 million so the Wichita company can keep operating at the level Boeing needs.