Airworthiness Directives; Bombardier, Inc. Airplanes

We are adopting a new airworthiness directive (AD) for all Bombardier, Inc. Model CL-600-2B19 (Regional Jet Series 100 & 440) airplanes. This AD was prompted by reports of burr marks on the primary wheels, and cracked rings on the primary wheel shaft, on certain horizontal stabilizer trim actuators (HSTAs). This AD requires replacing certain HSTAs. We are issuing this AD to prevent burr marks on the primary wheels, and cracked rings on the primary wheel shaft, on certain HSTAs, which may lead to a disconnect of the pitch trim surface and subsequent loss of pitch control, resulting in loss of control of the airplane.