Boeing is in talks to buy back Spirit Aerosystems, which makes fuselages for Boeing’s 737 Max jets, according to a person familiar with the matter, as both companies scramble to stamp out manufacturing flaws on the top-selling plane.

Shares of Spirit were up 13% as of early afternoon on Friday, while shares of Boeing were down about 1%. Spirit Aerosystems had a market capitalization of $3.3 billion as of Thursday’s close.

“We do not comment on market speculation,” a spokesperson for Spirit Aerosystems told CNBC. Boeing also declined to comment.

Boeing in 2005 spun off operations in Kansas and Oklahoma that became the present-day Spirit Aerosystems. About 70% of Spirit’s revenue last year came from Boeing, and about a quarter comes from making parts for Boeing’s main rival, Airbus.

The repurchase talks were first reported by the Wall Street Journal.

It comes less than two months after a section of a Boeing 737 Max 9 plane blew out during an Alaska Airlines flight. The Federal Aviation Administration temporarily grounded all of the planes in January, leading to investigations into the accident and Boeing’s production lines.

It was the latest and most serious in a host of flaws on the Boeing 737 Max, Boeing’s best-selling jet.

The bolts on the door plug of the Max involved in the January accident appeared not to have been attached when it left Boeing’s Renton, Washington, factory, according to a preliminary report from the National Transportation Safety Board.

Boeing has disclosed several production problems and quality flaws on the fuselages that Spirit makes, including incorrectly drilled holes and incorrect spacing on some fuselage components, problems that slowed deliveries of new jets to airlines.