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

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Bombardier Model CL-600-2B19 (Regional Jet Series 100 & 440) airplanes, that currently requires installation of protective tape on the fire and overheat control unit located in the flight compartment. This amendment requires the installation of protective tape and adds repetitive inspections of the condition of the protective tape and related corrective action. This amendment also mandates eventual replacement of the existing fire and overheat control unit with a modified unit, which ends the repetitive inspections. Additionally, this amendment adds airplanes to the applicability in the existing AD. The actions specified by this AD are intended to prevent fluid contamination inside the fire and overheat control unit, which could result in a false fire alarm and consequent emergency landing. This action is intended to address the identified unsafe condition.