Excel-Jet of Monument, Colo., is suing the FAA over the June 2006 crash of its proof-of-concept Sport-Jet, which was destroyed on takeoff from Colorado Springs Airport. According to witnesses, the single-engine composite jet rolled to the left, hit the runway and cartwheeled down the runway just after takeoff. Test pilot James Stewart and flight-test engineer John Welty sustained only minor injuries. The NTSB determined the probable cause to be “a loss of control for an undetermined reason during takeoff/initial climb that resulted in an in-flight collision with terrain.” According to Excel-Jet president Bob Bornhofen, the crash was caused by wake turbulence created by a Dash 8 twin turboprop that had just taken off, though the NTSB report dismisses this theory. The lawsuit claims that “air traffic control cleared the aircraft for takeoff behind a large commercial aircraft, in violation of mandatory separation requirements.” The prototype had logged 24 hours of flight time before the accident.