Airworthiness Directives; Bombardier, Inc. Airplanes

We are adopting a new airworthiness directive (AD) for certain Bombardier, Inc. Model CL-600-2B16 (CL-604 Variant) airplanes. This AD was prompted by reports of loose, broken, or backed-out spur gear bolts on the horizontal stabilizer trim actuator (HSTA). This AD requires a revision to the airplane flight manual, a revision to the maintenance or inspection program, as applicable, and replacement of HSTAs having certain part numbers. We are issuing this AD to detect and correct loose spur gear bolts on the HSTA, which, if combined with the failure of the primary load path, could lead to failure of the HSTA and subsequent loss of the airplane.