Bombardier Model CL-600-1A11 (CL-600), CL-600-2A12 (CL-601), and CL-600-2B16 (CL-601-3A and CL-601-3R) Airplanes - 2005-NM-156-AD

Comment on [Docket No. FAA-2005-22627; Directorate Identifier 2005-NM-156-AD; Amendment 39-14425; AD 2005-26-04] RIN 2120-AA64 For some reason we overlooked the issuance of this action as an NPRM and are now forced to respond to the final rule. We apologize for the oversight. This action requires modification or replacement of the horizontal surface trim actuator (HSTA) of certain Bombardier aircraft. Because a Goodrich service bulletin is referenced, we infer that Goodrich is the manufacturer of the HSTA installed by the manufacturer on the affected aircraft. However, there are other HSTA and components approved under 14 CFR § 21.303 (PMA) that may be installed on these aircraft. Because the exact requirements are buried in manufacturer service bulletins that are proprietary documents and not generally available to the public it is impossible to accurately determine if any of the alternatively approved parts exist or are in use. Airframe manufacturers, especially those not located in the United States, universally ignore the possibility that their aircraft may have been modified since delivery. Therefore their service documents may not apply in certain instances and cannot be adopted ver batim without further investigation. We therefore suggest and request the following: (1) That the action be restricted in applicability to those aircraft where the defective HSTA is installed. (2) That the action identify by manufacturer and part number the defective components so that parts vendors, maintenance facilities and the considerable PMA industry can be apprised of the defect and take appropriate actions. It is possible that PMA alternatives may exist that were approved by identical design criteria and that the defect may therefore exist on these components. We also suggest that the language addressing applicability be expanded to include any such parts that may now or in the future exist. (3) That any mandated replacement parts or components be identified by manufacturer and part number and include the appended phrase "or other FAA approved equivalent part." (4) That the prohibition of installation of an HSTA on these aircraft be restricted to those known to be defective. For example, a PMA HSTA may not suffer the same defect as the Goodrich part and should not be required to be modified when such modification is inappropriate and therefore unnecessary. (5) That the service bulletins be published in the dms in pdf format. (If the Canadian AD, which is not appropriate for US operators can be published, certainly the applicable service bulletins should also be.) Modification and Replacement Parts Association (MARPA) Jack Buster AD Committee