The long-troubled partnership between AgustaWestland and Bell Helicopter to develop a civil tiltrotor is officially over. After years of messy public discord, the companies had announced a preliminary agreement in June for AgustaWestland, pending regulatory approvals, to assume the assets of Bell/Agusta Aerospace, the joint entity formed to develop the aircraft.

AgustaWestland announced on Tuesday that the acquisition has been completed and that a new U.S.-based entity would be formed to finish certification of the tiltrotor in 2015 or 2016. Development work will be based at AgustaWestland’s facility in Cascina Costa, Italy, where a third AW609 prototype is now under construction.

The 609 program was announced in 1996 and the first prototype flew in 2003. Two test aircraft have flown more than 600 hours at up to 25,000 feet and 275 knots. AgustaWestland said 85 percent of the flight envelope tests are complete and claims that orders for 70 AW609s remain in place.

However, many of those orders are price conditional, and the company could not immediately provide additional details on the new unit price and the viability of these orders.