The first ship, America, LHA 6, is 25% complete.
The defense contractor will use the funds to buy long lead-time materials and major equipment, such as the main reduction gears, for the new ship and to do initial design and planning. The work will be done at the company's Gulf Coast facilities.
If all contract options are exercised, the value could reach $193 million.
"This contract marks the first milestone for the Navy's newest large-deck amphibious ship," said Kevin Jarvis, vice president of large deck programs. "Procuring long-lead material in advance of starting construction helps the shipbuilder manage cost and schedule, and managing our supply chain is one of our top priorities in shipbuilding."
LHA 7 will be 844 feet long and 106 feet wide and weigh 44,854 tons. A hybrid propulsion system can push it to speeds of 22 knots or more on gas turbines, and it also will run on auxiliary electric propulsion motors. It will accommodate 1,204 crew and 1,871 troops.
Northrop's shares closed at $54.44 and were inactive after hours. The stock was down 3% as of the close.