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Comment on [Docket No. FAA-2005-20803; Directorate Identifier 2005-CE-19-AD; Amendment 39-14433; AD 2005-26-12] RIN 2120-AA64 The subject regulatory action requires the replacement of certain brackets with brackets of "new and improved" design and goes on to specify the parts to be installed by part number. It is ironic that two airworthiness directives published on the same day with similar requirements are treated in entirely different ways. Here is the comment submitted on [Docket No. FAA-2005-22156; Directorate Identifier 2005-CE-43-AD; Amendment 39-14435; AD 2005-26-14] RIN 2120-AA64 __________________________________________________________________________________ Many, if not most, airworthiness directives(AD) are merely restatements of manufacturer's service documents. Problems can arise from this procedure with respect to 14 CFR § 21.303 (PMA) since the ramifications of this law are generally ignored in the service documents. The most frequent problem that arises is the service document specifying a defective part numbered part with the requirement that the defective part be replaced by a "new and improved" part numbered part. The service document and, all too frequently, the resulting AD fail to address the possibility that a PMA part may be installed in lieu of the original part. Since the PMA part may often share the identical design data with the original part while carrying a completely different part number it is possible the AD will not address certain defective PMA parts installed on the aircraft thereby permitting the unsafe condition to continue. It is also possible that a "new and improved" PMA version of the defective original part may already exist in the marketplace. Therefore, specifying one approved part in preference to a different, but also approved part will impart a commercial advantage to one manufacturer over the other. In either case, simply echoing part numbers without some qualifying language places the AD in conflict with existing law (FAR 21.303) AD writers frequently refer to the clause in the AD or proposed AD allowing alternative methods of compliance thereby implying that the use of a PMA part is such a method. It is not. A PMA part is already approved by operation of existing law and needs no further approval for installation and use. Therefore, this commenter, Modification and Replacement Parts Association (MARPA) requests that the final action include the phrase "or other FAA-approved equivalent part." after the part number of the part mandated to be installed. Jack Buster AD Committee And here is the comment response issued by the FAA What is the commenter's concern? The commenter states that the PMA part may often share the identical design data with the original part while carrying a completely different part number; therefore, it is possible the AD will not address certain defective PMA parts installed on the aircraft, allowing the unsafe condition to continue. The commenter also states that it is possible that a ``new and improved'' PMA version of the defective original part may already exist in the marketplace. Therefore, specifying one approved part in preference to a different, but also approved part, will impart a commercial advantage to one manufacturer over the other. The commenter requests that the final rule AD action be changed to address the replacement of identical, defective PMA parts and allow replacement with an identical, improved PMA part. What is FAA's response to the concern? We agree with the commenter. We will change the final rule AD action to include the phrase to cover the PMA replacement parts and add information to clarify the phrase ``or FAA-approved equivalent part number.'' We request that both regulatory actions provide for consideration of possible PMA alternative parts. Modification and Replacement Parts Association Jack Buster AD Committee