The Army awarded the contract in December in the hopes of ending a years-long competition for its next-generation helicopter and partially replace its fleet of more than 2,000 medium-class UH-60 Black Hawk utility helicopters built by Sikorsky since the 1970s.

The Army has said it plans to fly its remaining Blackhawk fleet through the 2060's.

(Reporting by Mike Stone in Washington; Editing by Leslie Adler)