Sikorsky Aircraft, a unit of United Technologies, and Lockheed Martin have bagged a $1.28bn contract to develop a new combat rescue helicopter (CRH) for the US Air Force.
The deal could eventually be worth about $7.9bn (£4.6bn, €5.8bn).
The initial contract covers the development and delivery of four CRHs based on Sikorsky's UH-60 Black Hawk helicopter -- the US Air Force has, for nearly 15 years, been trying to replace its aging fleet of HH-60G Pave Hawk rescue helicopters.
The Air Force said Sikorsky and its key supplier, Lockheed, beat the service's affordability target by about $700m. Lockheed will supply the mission systems and special equipment for the new helicopters.
Sam Mehta, president of Sikorsky Defense Systems and Services, told Reuters that Sikorsky bid aggressively to secure the contract.
The new contract - and a separate one for a new presidential helicopter - will boost Sikorsky's production 2019 onwards, but the firm faces challenges in the near-term owing to waning US military spending, Mehta added.
On 24 June, the US Pentagon approved the sale of Black Hawk helicopters to Mexico, a deal worth $225m.
The CRH contract has suffered a fair share of controversy.
The US revisited the procurement programme in 2012 after protests from Sikorsky and Lockheed forced the government to cancel an earlier contract awarded to Boeing.
However, Boeing, Airbus and Northrop Grumman exited the 2012 bidding process arguing that the Air Force had altered its requirements to favour Sikorsky's helicopter.