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-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) airplanes; and Model MD-88 airplanes; was published in the Federal Register on June 18, 2003 (68 FR 36523). That action proposed to require a general visual inspection for chafing of the power feeder cables of the auxiliary power unit (APU), and repair if necessary. That action also proposed to require replacement of a support bracket located on the left side of the lower cargo compartment with a new "U" shaped bracket. \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\nSupport for Proposed Rule \n\n\tOne commenter supports the proposed rule. \n\nRequest to Allow Alternative Method of Compliance (AMOC) Granted Previously \n\n\tThe other commenter requests that an AMOC previously granted for AD 94-09-02, amendment 39-8890 (59 FR 18720, April 20, 1994), be allowed to satisfy the requirements of the proposed rule. The commenter notes that AD 94-09-02 was previously issued to address a similar unsafe condition in the same area of the airplane, and that McDonnell Douglas MD-80 Service Bulletin 24-105 was approved as an AMOC for that AD. The commenter states that some of its airplanes had doublers previously installed to support the seat track in the modification area per that AMOC. The bracket identified in Revision 02 of McDonnell Douglas Alert Service Bulletin MD80-24A105 (referenced in the proposed rule as the appropriate source of service information for accomplishing the specified actions) could not be used at these locations; therefore, the commenter retained the doubler-bracket in lieu of the new bracket specified in the service bulletin. \n\n\tThe FAA does not agreeto allow the specified AMOC granted for AD 94-09-02 to satisfy the requirements of this AD. That AMOC was granted based on information contained in McDonnell Douglas MD-80 Service Bulletin 24-105, dated August 15, 1989. However, since that AD was issued and that AMOC granted, McDonnell Douglas Alert Service Bulletin MD80-24A105, Revision 02, dated January 24, 2000, was released. That revision, which was also upgraded to alert status, specifically requires additional work for airplanes previously modified in accordance with previous issues of that service bulletin. Therefore, airplanes on which the described AMOC was approved are subject to the unsafe condition addressed by this AD, and operators must accomplish the actions required by this AD. No change to the final rule is made in this regard. \n\nRequest To Revise the Work-Hour Estimate of the Cost Impact Section \n\n\tThe same commenter points out that the proposed rule estimates 1 work hour to accomplish the proposed actions; however, McDonnell Douglas Alert Service Bulletin MD80-24A105, Revision 02, lists 3 work hours for those actions--a figure which the commenter asserts more closely reflects the time required for the specified tasks. \n\n\tFrom this comment, we infer that the commenter is requesting that we revise the work-hour estimate in the Cost Impact section of the proposed rule. We do not agree. As stated in the preamble of the proposed rule, the cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. Those 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. The work-hour figure listed in the referenced service bulletin includes time for access and close up. No change is made to the final rule in this regard. \n\nClarification of Requirements of Paragraph (c) of the Final Rule \n\n\tWe inadvertently omitted reference to the specific service information for accomplishing the required support bracket replacement specified in paragraph (c) of the proposed rule. It was our intent that the required replacement be accomplished in accordance with McDonnell Douglas Alert Service Bulletin MD80-24A105, Revision 02, dated January 24, 2000. We have revised paragraph (c) of this final rule to specify that the required replacement be done in accordance with that service bulletin. \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 change previously described. The FAA has determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nLabor Rate Increase \n\n\tAfter the proposed rule was issued, we reviewed the figures we have used over the past several years to calculate AD costs to operators. To account for various inflationary costs in the airline industry, we find it necessary to increase the labor rate used in these calculations from $60 per work hour to $65 per work hour. The cost impact information, below, reflects this increase in the specified hourly labor rate. \n\nCost Impact \n\n\tThere are approximately 634 airplanes of the affected design in the worldwide fleet. The FAA estimates that 438 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 inspection and replacement of the bracket, and that the average labor rate is $65 per work hour. Required parts will cost approximately $147 per airplane. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $92,856, or $212 per airplane. \n\n\tThe cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, 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\nAccordingly, 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\n1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\n§ 39.13 (Amended) \n\n2. Section 39.13 is amended by adding the following new airworthiness directive: