Airworthiness Directives; Bombardier Model CL-600-2B16 (CL-604) Airplanes and Model CL-600-2B19 (Regional Jet Series 100 & 440) Airplanes

The FAA is superseding an existing airworthiness directive (AD) that applies to certain Bombardier Model CL-600-2B16 (CL-604) airplanes and Model CL-600-2B19 (Regional Jet Series 100 & 440) airplanes. These models may be referred to by their marketing designations as RJ100, RJ200, RJ440, CRJ100, CRJ200, CRJ440, and CL-65. The existing AD currently requires revising the Emergency Procedures section of the airplane flight manual (AFM) to advise the flightcrew of additional procedures to follow in the event of stabilizer trim runaway. For certain airplanes, the existing AD also requires revising the Abnormal Procedures section of the AFM to advise the flightcrew of procedures to follow in the event of MACH TRIM, STAB TRIM, and horizontal stabilizer trim malfunctions. This AD requires revising the same Emergency and Abnormal Procedures sections of the AFM to advise the flightcrew of revised/additional procedures. This AD also requires revising the Normal section of the AFM to require a review of the location of certain circuit breakers and a functional check of the stabilizer trim system. This AD also requires installing circuit breaker identification collars and provides an optional terminating action for the requirements of the AD. This AD also removes airplanes from the applicability of the existing AD. This AD results from reports of uncommanded horizontal stabilizer trim motion. We are issuing this AD to ensure that the flightcrew is advised of appropriate procedures to follow in the event of uncommanded movement or stabilizer trim runaway. Failure to follow these procedures could result in excessive uncommanded movement of the horizontal stabilizer trim actuator (HSTA) and loss of ability to use trim switches to override uncommanded movement or yoke disconnect switches to disconnect the HSTA, which could result in reduction of or loss of pitch control and consequent reduced controllability of the airplane.