Bell Helicopter received a $423 million contract modification to manufacture and deliver 25 Lot 14 AH-1Z Viper helicopters to the U.S. Marine Corps.

The contract was awarded by the U.S. Navy in support of the H-1 program, an effort to supply the Marines with upgraded attack helicopters. Under the program, Marines receive AH-1Z Vipers and UH-1Y Venom rotorcraft to replace their aging fleets of AH-1W Super Cobras and UH-1N Twin Hueys.

The modification award comes just a day after the company received a $49 million contract to procure long-lead items to support the AH-1Z.

The U.S. Department of Defense says the work will be performed at Fort Worth and Amarillo in Texas, and expects it to be complete by February 2020.

Bell Helicopter received all funding at the time of the modification award, comprised of Fiscal 2016 and Fiscal 2017 procurement funds. The Naval Air Systems Command in Patuxent River, Md., is the contracting activity.

The AH-1Z Viper, also referred to as the "Zulu", is a twin-engine attack helicopter based on the design of the AH-W SuperCobra. The four-blade rotorcraft is equipped with a composite main rotor system, an updated transmission, and new target identification technology.