Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Bombardier Model CL-600-1A11, CL-600-2A12, CL-600-2B16, and CL-600-2B19 series airplanes, that currently requires an inspection to detect cracking in the rudder control quadrant; replacement of any cracked quadrant with a new assembly; and retorquing of the castellated nut, as necessary. This action would require a follow-on inspection of certain rudder control quadrants to detect cracks that start at the inside root radius of the spigot; modification of any cracked quadrant; and eventual modification of certain quadrants. This action also would add airplanes to the applicability of the existing AD. This proposal is prompted by the development of a modification, which, when installed, will positively address the identified unsafe condition. The actions specified by the proposed AD are intended to prevent loss of rudder control due to stress corrosion of the rudder control quadrant.