Defense contractors Northrop Grumman Corp. and Lockheed Martin said Monday that their joint venture was awarded an $86 million contract to develop and repair radar systems for Apache helicopters.

The venture, Longbow LLC was awarded a four-year contract by Agusta Westland to provide engineering services, integrated logistics and repairs for the all-weather radar systems.

The work will be performed at Northrop Grumman facilities in Baltimore; Lockheed Martin facilities in Ocala and Orlando, Fla., and Wattisham Airfield in the United Kingdom.

Separately, Los Angeles-based Northrop announced that its navigation systems division broke ground on a plant expansion in Salt Lake City. The facility makes navigation systems for military and commercial clients and has about 750 workers.

Northrop stock was up 55 cents, or less than 1 percent, to $61.76 in midday trading on the New York Stock Exchange.