The US Federal Aviation Administration has finalised an airworthiness directive that requires Bombardier CRJ700/900 operators to update aircraft flight manuals for cold weather operations related to frost, snow, slush and ice and the wings and leading edges of the aircraft.
First proposed in May, the directive applies to 336 aircraft on the US registry. Operators will have two weeks from 8 January, the effective date of the AD, to update the flight manuals with cold weather procedures developed by Transport Canada.
The FAA notes that frost, snow, slush or ice on the wing leading edges and upper wing surfaces "may change the stall speeds, stall characteristics and the protection provided by the stall protection system, which could result in reduced controllability of the aircraft".