Summary
The FAA proposes to supersede an existing airworthiness directive (AD) that 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 proposed AD would require 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 reidentification of the mounting tray of the contactors; as applicable. This proposed AD also limits the applicability of the existing AD. This proposed AD results from incidents of short circuit failures of certain AC contactors located in the avionics bay. We are proposing this AD to prevent short circuit failures of certain AC contactors, which could result in arcing and consequent smoke or fire.