Airworthiness Directives; Bombardier Model CL-600-2B19 (Regional Jet Series 100 & 440) Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Bombardier Model CL-600-2B19 (Regional Jet Series 100 & 440) series airplanes, that requires replacement of the existing smoke detectors in the cargo compartment with new, improved smoke detectors. This amendment is prompted by mandatory continuing airworthiness information from a civil airworthiness authority. The actions specified by this AD are intended to prevent false smoke warnings from the smoke detectors in the cargo compartment. A false smoke warning prompts the flightcrew to discharge fire extinguisher bottles, leaving those bottles depleted in the event of an actual fire. Repeated false smoke warnings create uncertainty as to whether an emergency landing and emergency evacuation of passengers and flightcrew is warranted.