A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-9-10, -20, -30, -40, and -50 series airplanes and C-9 airplanes was published in the Federal Register on June 6, 2001 (66 FR 30345). That action proposed to require replacing the transformer ballast assembly in the first officer's console with a new, improved ballast assembly. \n\nComments \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. \n\n\tOne commenter indicates that its DC-9 airplanes will be retired from service within the proposed compliance time of the AD and that, therefore, it has no comment. \n\nRequest To Reference Latest Service Bulletin \n\n\tSeveral commenters request that the proposed AD refer to the latest service bulletin. They state that McDonnell Douglas Alert Service Bulletin DC9-33A114, dated November 1, 1999 (which is referenced in the notice of proposed rulemaking (NPRM) as the appropriate source of service information), erroneously indicates that the ballast assembly to be replaced is located in the first officer's console rather than in the pilot's console. A revision to the service bulletin (Revision 01, dated February 15, 2000) corrects the error and, therefore, should be cited in the AD as the service bulletin to use. \n\n\tThe FAA concurs. Since issuance of the NPRM, the FAA has reviewed and approved McDonnell Douglas Alert Service Bulletin DC9-33A114, Revision 01, dated February 15, 2000. The service bulletin describes procedures for replacing the transformer ballast assembly with a new, improved ballast assembly and identifies the pilot's console as the location of the ballast assembly. For clarification purposes, we have revised this AD to refer to the "pilot's console" rather than the "first officer's console" as thelocation of the transformer ballast assembly to be replaced. \n\nRequest To Allow Replacement With a "New or Serviceable" Ballast Assembly \n\n\tAnother commenter asks that operators be allowed to replace the existing ballast assembly with either a serviceable ballast assembly or a new, improved ballast assembly. The commenter suggests that replacement of a ballast assembly with a serviceable improved ballast assembly would provide an acceptable level of safety. \n\tThe FAA does not concur, because the part numbers of the old (serviceable) transformer ballast assembly are different from those of the new, improved assembly. Thus, there would be no way to tell whether ballast assemblies with the old part numbers were "old, unimproved" or "old, improved" assemblies. \n\nAdditional Change to Final Rule \n\n\tThe number of airplanes of U.S. registry affected by this AD has decreased since publication of the NPRM from approximately 543 to approximately 475. The estimated cost impact of the rule on U.S. operators has decreased correspondingly from between $781,377 and $1,042,560 (depending on the cost of parts) to between $683,525 and $912,000. \n\nConclusion \n\n\tAfter careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCost Impact \n\n\tThere are approximately 575 Model DC-9-10, -20, -30, -40, and -50 series airplanes and C-9 airplanes of the affected design in the worldwide fleet. The FAA estimates that 475 airplanes of U.S. registry will be affected by this AD, that it will take approximately 1 work hour per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost between $1,379 and $1,860 per airplane. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be between $683,525 and $912,000, or between $1,439 or $1,920 per airplane. \n\n\tThe cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. \n\nRegulatory Impact \n\n\tThe regulations adopted herein will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. \n\n\tFor the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \n\n\tAccordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n\t1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\nSec. 39.13 (Amended) \n\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: