Northrop Grumman Corp. said Wednesday that Australia will buy 24 advanced Super Hornet fighter bombers in a deal worth about $4.6 billion.

The Super Hornet aircraft are partially assembled in El Segundo at a Northrop facility. The airframe is built by the prime contractor on the contract, Chicago-based Boeing Co., but nearly all of the interior electronics and fuselage assembly are completed at the Northrop facility, which employees about 1,200 and is currently on a $3.2 billion contract.

The order will keep the plant open at least until 2012, a Northrop spokesman said. The radar for the jets is also build at a Raytheon facility adjacent to the Northrop plant.

The Hornet is the U.S. Navy’s primary fighter/bomber and will remain in service until at least 2030, the Navy recently said.

Shares in Los Angeles-based Northrop were up 22 cents to $72.31 in afternoon trading Wednesday on the New York Stock Exchange.