The order, won by the group's Westland Aerospace division on the Isle of Wight, involves making composite engine casings for 180 of Lockheed's new C-130J aircraft.
Westland, which won the contract in the face of stiff competition, said the work would help to safeguard jobs.
This is the latest in a series of overseas aerospace orders secured by Westland. Other customers include Boeing, Dornier de Havilland and Saab.
The C-130J is the latest variant of Lockheed's best-selling Hercules, over 2,000 of which have been made to date. Sales of around 700 of the latest model are expected, Westland said.
The contract includes design of the lower cowl and all nacelles - streamlined engine coverings - for the C-130J and the supply of complete nacelles for other variants of the plane.
The C-130J is powered by the new Allison GMA2100 engine and marks the second Allison contract won by Westland.
Development of the C-130J project is being funded jointly by Lockheed and its team of risk-sharing UK contractors.Reuse content