Brazil’s Embraer and its U.S. partner, Sierra Nevada Corp., confirmed that the A-29 Super Tucano won the U.S. Air Force Light Air Support (LAS) competition. Hawker Beechcraft continued to protest the decision, by appealing to the Court of Federal Claims, and the Air Force issued a stop work order this week, just days after Sierra Nevada was awarded a $355 million contract for an initial 20 aircraft, as well as training equipment and support.

Sierra Nevada said it won “a fair and open” contest that had been favorably reviewed by the Government Accountability Office (GAO). “We remain confident that the issue will be resolved expeditiously,” Sierra Nevada added.

According to the GAO, the Air Force found “multiple deficiencies and significant weaknesses” in Hawker Beechcraft’s AT-6 proposal for the LAS. The GAO supported an Air Force ruling that the company’s request for a debrief was filed late and was therefore invalid.

Sierra Nevada noted that the Super Tucano was built specifically for counter-insurgency missions and thus required no further development. Six air forces are already using more than 150 of the aircraft in LAS-type missions. More than 18,000 combat hours had been logged without a loss, it added.

Hawker Beechcraft said that the AT-6 would offer logistics and cost efficiencies by adding the A-10C mission system and MC-12W sensor suite to the proven T-6 airframe. The Kansas-based OEM continued to claim that the AT-6 is the all-American solution.

Embraer and Sierra Nevada said that Super Tucano would be built in Jacksonville, Fla., by American employees, using parts or services supplied by more than 70 U.S. companies in 21 states.

According to Hawker Beechcraft, the LAS contract will ultimately be worth nearly $1 billion. The company has been downsizing to match depressed market conditions, and was hoping to boost turnover at its Wichita operation by clinching the LAS award.