Europe’s Airbus has finalized an agreement to take some assets from Spirit AeroSystems, both companies said Monday, completing a critical part of a transatlantic carve-up of the struggling supplier with US rival Boeing.

European plane maker Airbus will take over parts of Spirit AeroSystems as it and Boeing carve up the key supplier in an effort to improve production quality.

Airbus will take over some parts of Spirit AeroSystems as Spirit is reacquired by Boeing. “Spirit has entered into a definitive agreement with Airbus SE to transfer ownership of certain assets and sites involved in the production of Airbus aerostructures to Airbus,” a news release from Spirit said.