One of the black boxes from the Cessna Citation 550 that crashed near Statesville Regional Airport has been recovered and sent to Washington DC for examination, as investigators continue to analyze the December 18 accident.The jet crashed after attempting to return amid low clouds and rain, killing former NASCAR driver Greg Biffle, his family and three crew members, and authorities plan a preliminary NTSB report within 30 days with a full investigation in up to 18 months.