The FAA on April 14 issued an Airworthiness Directive for all Bombardier Challengers, as well as the derivative CRJ100 and 440 regional jets, that requires revising the aircraft flight manuals to modify the cold-weather operations limitations and include additional limitations and procedures. The FAA stated that AD 2008-08-06 results from reports of “uncommanded roll during takeoff” and said it is necessary to “prevent possible loss of control on takeoff resulting from even small amounts of frost, ice, snow or slush on the wing leading edges or forward upper wing surfaces.” The directive, which supersedes an AD issued in February 2005 regarding the same issue, became effective April 21.