In light of Hawker Beechcraft’s pending litigation over award of a light attack aircraft contract to competitor Sierra Nevada, the U.S. Air Force has issued a temporary stop-work order. Hawker Beechcraft filed suit after learning that the GAO had dismissed its protest over exclusion from the bidding. Sparks, Nev.-based Sierra Nevada partnered with Brazilian aircraft manufacturer Embraer to offer U.S.-assembled Embraer Super Tucanos in the bidding process. The contract could be worth as much as $1 billion, with deliveries expected to begin next year.