Summary
We propose to adopt a new airworthiness directive (AD) for certain Bombardier, Inc. Model CL-600-2B16 (CL-604 Variant) airplanes. This proposed AD was prompted by reports of loose, broken, or backed out spur gear bolts on the horizontal stabilizer trim actuator (HSTA). This proposed AD would require a revision to the airplane flight manual, a revision to the maintenance or inspection program, and replacement of HSTAs having certain part numbers. We are proposing 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 control of the airplane.