The U.S. Air Force will restart its stalled $1 billion competition to buy light attack aircraft for the Afghanistan military, it said today.

The military will issue a draft request for proposals April 17 and a final version April 30, the service said in an e-mailed statement. A new award is scheduled for early 2013.

The Air Force on Feb. 28 canceled a disputed $1 billion contract to Sierra Nevada Corp. after determining the documentation used to make the award was flawed.

Sierra Nevada and its Brazilian subcontractor, Embraer SA (EMBR3), will again compete against Hawker Beechcraft Corp. Hawker, a closely held company that is 49 percent-owned by Goldman Sachs Group Inc. (GS), had protested the Defense Department’s December decision, which gave Sierra the order to provide the aircraft for the Afghan military.