Lockheed Martin [LMT], the government of Turkey, and members of the Turkish aerospace industry activated contractual agreements worth $3.5 billion under the Turkish Utility Helicopter Program (TUHP) to build and deliver 109 T70 utility helicopters, the company said June 16.

The T70 is based on UH-60 Black Hawk utility aircraft made by Sikorsky, which was purchased by. Lockheed Martin in 2015 and now operates as a business unit of the defense giant. The agreements were approved by both the United States and Turkish governments and license TUHP’s prime contractor Turkish Aerospace Industries (TAI) to deliver the helicopters over the next 10 years.

Aircraft delivery may begin as early as 2021 to six Turkish agencies including the Land Forces, Air Force, Gendarme, Special Forces, National Police, and Directorate General of Forestry.

TAI is also set to deliver an equal number of baseline S-70i Black Hawk aircraft for export to Sikorsky over a 30-year timeframe. Sikorsky and TAI are currently in discussions to establish a joint marketing team to support Sikorsky’s sale of S-70i helicopters to new markets in the Middle East, Central Asia, and Africa, Lockheed Martin said.

“These finalized agreements mark the beginning of an important and highly collaborative industrialization partnership with Turkish industry that will endure for decades,” Dan Schultz, Sikorsky president, said in a statement.

“We thank the Republic of Turkey for choosing a Sikorsky multi-role helicopter, and we congratulate Turkish industry for building this manufacturing capability,” Schultz added.

Sikorsky plans to provide TAI with engineering data to establish an assembly line and begin manufacturing the T70s during the latter half of 2016. Sikorsky will also deliver the first five aircraft in kit form for assembly by TAI starting in 2018.

The first Turkish-built T70 is expected to be certified and qualified for delivery to Turkey’s government by 2021.

Thereafter, TAI is set to gradually increase its manufacturing scope beyond the final assembly and test stages. The increased scope will include manufacturing all airframe structure and composite rotor blades.

The agreement also stipulates Alp Aviation, a Sikorsky joint venture, will precision-machine the dynamic components, flight controls, and assemble landing gear and transmissions. Turkish military radio and electronic maker Aselsan and Sikorsky will co-develop an enhanced digital cockpit, the Integrated Modular Avionics System (IMAS). Turkish Engine Industries (TEI) will build the helicopter engines under license from General Electric [GE].

Sikorsky will also transfer to Aselsan a new S-70i helicopter to be used as the Prototype Turkish Utility Helicopter for the qualification of a new avionics system in 2019 to facilitate the development and integration of the IMAS.

The agreement calls for TAI to produce T70s in two configurations, 89 as common utility and 20 in a firefighting version for the Directorate General of Forestry. All of the 109 T70s are to be delivered by 2026.

The program also includes options for TAI to produce up to 600 total T-70 and S-70i helicopters.