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

The FAA is adopting a new airworthiness directive (AD) for all Bombardier Model CL-600-2B19 (Regional Jet Series 100 & 440) airplanes. This AD requires revising the Certification Maintenance Requirements and the Maintenance Review Board Report sections of the Canadair Regional Jet Maintenance Requirements Manual to include changes and additions to checks of the aileron power control units (PCUs) and a change to the interval of the backlash check of the aileron control system. This AD results from a report that data collected from in- service airplanes show that approximately 19 percent of aileron backlash checks conducted at 4,000-flight-hour intervals reveal that aileron backlash wear limits are being exceeded. We are issuing this AD to prevent exceeded backlashes in both aileron PCUs, which, if accompanied by the failure of the flutter damper, could result in aileron vibration/flutter and reduced controllability of the airplane.