Summary
We propose to adopt a new airworthiness directive (AD) for certain Bombardier, Inc. Model CL-600-2B19 (Regional Jet Series 100 & 440) airplanes. This proposed AD was prompted by reports of the horizontal stabilizer trim actuator (HSTA) spur gear bolts inside the gearbox found loose, broken, or backed out due to incorrect bending of the anti-rotation tab washer and the improper application of glue during installation. This proposed AD would require replacing certain HSTAs with a new HSTA. This proposed AD would also require revising the airplane flight manual (AFM) and the maintenance or inspection program, as applicable. We are proposing this AD to prevent failure of the HSTA and subsequent loss of control of the airplane.