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), DC-9-87 (MD-87), and Model MD-88 airplanes was published in the Federal Register on December 5, 2003 (68 FR 67978). That action proposed to require replacement of certain freeze protection ribbon heaters in the lavatory water supply system, and flushing, cleaning, and sterilizing the potable water system; disconnecting, coiling, and stowing the wiring of the freeze protection ribbon heater; or removal of freeze protection heaters. \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\nRequest for Credit for Actions Accomplished per Alternative Service Bulletin \n\n\tOne commenter requests that the FAA give credit for actions accomplished in accordance with McDonnell Douglas MD-80 Service Bulletin 38-56, dated September 20, 1991. The commenter states that the McDonnell Douglas service bulletin refers to Jamco Corporation Service Bulletin MD080-25-829 as an additional source of service information for "instructions to replace the modular lavatory potable water supply hose and ribbon heater." \n\n\tWe agree, since we find that both Boeing Alert Service Bulletin MD80-25A381, dated August 5, 2002; and McDonnell Douglas MD-80 Service Bulletin 38-56, dated September 20, 1991, as revised by McDonnell Douglas MD-80 Service Bulletin Change Notification 38-56 CN1, dated June 11, 1992; refer to Jamco Corporation Service Bulletin MD080-25-829 as an additional source of service information for instructions on replacing the existing freeze protection ribbon heater in the lavatory water supply system with a new, reidentified heater hose assembly. Therefore, we have determined that completion of all the stepsin the Accomplishment Instructions of McDonnell Douglas MD-80 Service Bulletin 38-56, dated September 20, 1991, is acceptable for compliance with the corresponding actions specified in paragraph (a)(1) of this final rule. We have added new paragraph (b) to this final rule to give credit for accomplishment of the alternative service bulletin. \n\nRequest To Use Latest Revision of Jamco Service Bulletin \n\n\tAnother commenter requests that we revise the proposed AD to reference Revision 6 of Jamco Corporation Service Bulletin MD080-25-829 as an additional source of service information. The commenter states that Revision 6 is "in the approval cycle," and that if it is approved ". . . and the AD restates the version of the Jamco service bulletin, there will be a problem." The commenter provided no justification for the request. \n\n\tWe agree with the commenter's request to reference Jamco Corporation Service Bulletin MD080-25-829, Revision 6, dated March 10, 2003. We find that Revision 6of the Jamco service bulletin describes procedures that are essentially the same as the procedures described in Revision 5 of the Jamco service bulletin. Therefore, we have revised Note 1 of this final rule to reference Revision 6 of the Jamco service bulletin as an additional source of service information. \n\nExplanation of Change to Proposed Rule \n\n\tIn Note 1 of the proposed AD, we inadvertently omitted the revision level for Jamco Corporation Service Bulletin MD080-25-829. We have revised this final rule to specify Revision 6. \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 1,180 airplanes of the affected design in the worldwide fleet. The FAA estimates that 724 airplanes of U.S. registry will be affected by this AD, and that each airplane has approximately 3 lavatories, and that the average labor rate is $65 per work hour. Table 1 shows the estimated cost impact, based upon the action taken, for airplanes affected by this AD. \n\nTable 1.--Cost Impact\n\n\nAction\nWork hours per lavatory\nParts cost per lavatory\nCost per lavatory\nTotal cost\nReplace the existing freeze protection ribbon heater with a new, reidentified heater hose assembly; and flush, clean, and sterilize the potable water system; or\n6\n$2,344 to $3,208 (Depending on lavatory module configuration).\n$2,734 to $3,598 (Depending on lavatory module configuration).\n$5,938,248 to $7,814,856 (Depending on lavatory configuration) or $8,202 to $10,794 per airpalne.\nDisconnect, coil, and stow the wiring of the freeze protection ribbon heater; or\n2\n$0\n$130\n$282,360 or $390 per airpalne.\nRemove the freeze protection ribbon heater\n3\n$0\n$195\n$423,540 or $585 per airpalne.\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 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\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\n§ 39.13 (Amended) \n\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: