Airworthiness Directives; Cessna Aircraft Company 310, 320, 340, 401, 402, 411, 414, and 421 Airplanes

الملخص

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD would require you to install a placard that prohibits flight into known icing conditions and install a placard that increases published speed on approach 17 mph (15 knots) in case of an inadvertent encounter with icing. This proposed AD was prompted by an investigation of recent and historical icing-related accidents and incidents for the products listed above. We are proposing this AD to prohibit flight into known icing conditions as well as increase the approach speed in case of an inadvertent encounter with icing. This condition, if not corrected, could result in unusual flight characteristics that could lead to loss of control after flight into known icing conditions or an inadvertent encounter with icing conditions. Based on the data, an example of the unusual flight characteristics seen in many of the accidents is high sink speeds that resulted in a hard landing.