2005-CE-35-AD

Comment on [Docket No. FAA-2005-21835; Directorate Identifier 2005-CE-35-AD] RIN 2120-AA64 This proposed action requires the replacement of certain defective main landing gear bolts with "new and improved bolts." Both bolts are designated by manufacturer part number. Regulatory actions that derive from manufacturer issued service bulletins specifying parts by part number generally leave regulatory loop holes. Type certificate holders, particularly those of foreign origin, typically ignore the potential effect of 14 CFR 21.303 (PMA) upon recommended corrective actions. As a general rule there always exists the possibility that PMA parts approved as replacements for OEM parts may suffer from the same design defects present in the original. Because PMA parts frequently carry different part numbers from the OEM parts from which they derive they can be excluded from an action designed to correct a defect thereby creating a safety issue. Correspondingly, approved PMA parts equal to the parts mandated to be installed that are free of the defect can be excluded as a method of complying with the action. The regulatory action can thus appear to countermand an existing law (21.303) requiring an additional level of approval for a part already approved. It is unsettled law whether an airworthiness directive can contravene an existing federal aviation regulation. In the instant case the defective part can only be the OEM part so no concern is raised by restricting the corrective action just to that domain of parts. Further, there are no known or contemplated PMA alternatives to the part mandated to be installed and, we believe, none likely to be created in the future. This commenter, Modification and Replacement Parts Association (MARPA) therefore makes only a general comment that restricting parts to be replaced and parts to be installed to just those cited in the manufacturer service document is not good form and might establish a dangerous precedent. The usual method employed by AD writers to avoid this pitfall is to qualify the part number mandated to be installed by appending the term "or FAA-approved equivalent part number(s)." We believe such language to be adequate for replacement parts, but prefer a MARPA developed broader statement that also addresses possible alternatively numbered defective PMA parts: "The parts designated herein as requiring replacement or modification as well as those designated to be installed shall be interpreted broadly to also include any replacements parts approved under FAR 21.303 for the original equipment parts cited in this action. Nothing in this action prevents or precludes the installation of such alternatively approved parts provided such parts meet current airworthiness standards including those cited in this action." Jack Buster AD Committee