Summary
This document revises an earlier proposed airworthiness directive (AD), applicable to certain Bombardier Model CL-600-2B19 series airplanes, that would have required replacement of the existing smoke detectors in the cargo compartment with new, improved smoke detectors. That proposal was prompted by mandatory continuing airworthiness information from a civil airworthiness authority. This new action revises the proposed rule by including spare part information. The actions specified by this new proposed 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.