Russian state firm Rostekhnologii has agreed to acquire up to 85 Irkut MS-21s, including 50 firm aircraft.
The company reached the agreement, which Irkut values at $3.8 billion, during the MAKS Moscow air show. Deliveries will start around 2017 and run to 2022.
Rostekhnologii will take 35 MS-21-300s and 15 MS-21-200s, plus options on 35 more aircraft, through leasing operation Aviakapital-Servis, with Aeroflot lined up as a customer.
The deal came alongside a pact with lessor Ilyushin Finance which is taking 28 with 22 options.
Rostekhnologii has also signed a strategic partnership agreement with United Aircraft covering development of domestic airframes.
The purpose of the pact is to "create competitive Russian aircraft", said Rostekhnologii, and secure 10% of the global sales in the civil market by 2025, with domestic suppliers providing at least 70% of the systems.
Rostekhnologii and United Aircraft have identified four priority areas. These comprise new-technology aircraft - such as the Irkut MS-21 and Sukhoi Superjet - plus modernised types, like the Tupolev Tu-204SM, aircraft for the government, and a segment including the updated Antonov An-124 and An-70.
Their partnership comes in the wake of heavy criticism from the Russian government that the country's commercial air transport industry is weak and unable to compete with foreign manufacturers.
The two sides will create "innovative products" featuring advanced engines, modular avionics and composite materials.