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 a determination that certain maintenance tasks for the horizontal stabilizer trim actuator (HSTA) are inadequate. This proposed AD would require revising the maintenance or inspection program, as applicable, to incorporate new airworthiness limitations for the HSTA. We are proposing this AD to detect and correct premature wear and cracking of the HSTA, which could result in failure of the HSTA and consequent loss of control of the airplane.