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

The FAA is superseding an existing airworthiness directive (AD), which applies to certain Bombardier Model CL-600-2B19 (Regional Jet Series 100 & 440) airplanes. The existing AD currently requires inspecting contactors 1K4XD, 2K4XD, and K4XA to determine the type of terminal base plate, and applying sealant on the terminal base plates if necessary. This AD requires an inspection to determine if certain alternating current (AC) service and utility bus contactors have a terminal base plate made from non-G9 melamine material, and corrective actions if necessary; or re-identification of the mounting tray of the contactors; as applicable. This AD also limits the applicability of the existing AD. This AD results from incidents of short circuit failures of certain AC contactors located in the avionics bay. We are issuing this AD to prevent short circuit failures of certain AC contactors, which could result in arcing and consequent smoke or fire.