Visual and tactile inspections of the wings of Bombardier Challenger business jets and 50-seat CRJ regional jets whenever there is a risk of icing have been mandated in a just-issued US Federal Aviation Administration airworthiness directive (AD), which is effective immediately.
"Even small amounts of frost, ice, snow or slush on the wing leading edges or forward upper wing surfaces can cause loss of control at take-off," says the AD.
Following recommendations by UK and US accident investigation bodies and a similar AD actioned by Transport Canada on 16 February, operators have been told that visual inspection alone is not sufficient, and that tactile inspection in icing conditions is essential, with de-icing to be carried out if any ice or frost contamination is detected.
The US National Transportation Safety Board says: "The bottom line is that pilots should be aware that no amount of snow, ice or frost accumulation on the upper wing surface should be considered safe for take-off." The FAA's AD emphasises that contamination can cause "an adverse change in the stall speeds, stall characteristics, and the protection provided by the stall protection system."
The ADs have been prompted by recommendations in the accident report on the January 2002 take-off crash of a Challenger 604 at Birmingham, UK. Since then two fatal accidents in icing conditions - both of which occurred in November 2004 and are still under investigation - have involved a Challenger 604 business jet on take-off from Montrose, Colorado, and a Yunnan Airlines CRJ200 just after take-off from Baotou.
Source: Flight International
