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 all Boeing Model 727 airplanes was published in the Federal Register on November 4, 2003 (68 FR 62408). That action proposed to require an inspection of the bolts used to attach the forward cone bolt to the engine flange to determine if the attachment bolts are either H-11 steel bolts or cadmium-plated bolts. That action also proposed to require replacement of either H-11 steel bolts or cadmium-plated bolts with new corrosion-resistant steel bolts. \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 To Allow Use of Alternative Part \n\n\tOne commenter requests that the FAA revise the proposed AD to allow operators to use an alternative attachment bolt, part number (P/N) B27-53-031-111. The commenter states that, in accordance with Supplemental Type Certificates (STC) SA5839NM and ST00350AT, some airplane engines are modified with a heavyweight hush kit, which uses bolts made with corrosion resistant Inconel 718. The commenter considers these bolts to satisfy the intent of the proposed AD. \n\n\tThe FAA agrees. The AD does not specify what action should be taken if corrosion resistant bolts, P/N B27-53-031-111, are used to attach the forward cone bolt to the engine flange. Although these attachment bolts are not part of the original type design, allowing use of these attachment bolts in accordance with STC SA5839NM and ST00350AT will eliminate the need for an alternative method of compliance to the benefit of operators and the FAA. We have revised paragraph (a) of this AD accordingly. \n\nRequest To Extend Compliance Time \n\n\tThe same commenter also requests that the we revise the proposed AD to extend the proposed compliance time for the inspection from "18 months or 3,000 cycles, whichever is earlier," to 24 months to allow affected operators sufficient time to perform the inspection and parts replacement during a regularly scheduled maintenance interval. The commenter states that the compliance time of the proposed AD presents an operational hardship in ensuring adequate time for the parts replacement, if necessary, during a regularly scheduled maintenance check. The commenter considers that the adoption of the proposed compliance time of 18 months would require operators to schedule special times to do the inspection, at additional expense and downtime. \n\n\tWe do not agree with the commenter's request to extend the compliance time. In developing an appropriate compliance time for this action, we considered the safety implications and normal maintenance schedules for the timely accomplishment of the inspection and parts replacement. In consideration of these items, as well as the unpredictable nature of stress corrosion, we have determinedthat an 18-month interval will ensure an acceptable level of safety and allow the inspection and parts replacement to be done during scheduled maintenance intervals for most affected operators. \n\nRequest To Withdraw the Proposed AD \n\n\tOne commenter, on behalf of its members, requests that we withdraw the proposed AD. The commenter states that there are no reported failures of H-11 bolts, and that Stage 3 hushkits and the retirement of some Boeing Model 727 airplanes have significantly reduced the number of affected H-11 bolts. The commenter asserts that a maintenance program for inspection of the affected bolts would be sufficient for detecting cracking. \n\n\tWe do not agree. Although we have not yet received any report of cracked H-11 bolts found on Boeing Model 727 airplanes, we have received a report that an operator found one cracked and two fractured H-11 bolts in the side load underwing fittings of a Model 767-200 series airplane, as stated in AD 2002-10-51. We also point out that the nature of stress corrosion is unpredictable. Furthermore, we have determined that continued service for an unsafe condition for an unknown period of time conflicts with the intent of this AD. Thus we have not changed the final rule regarding this issue. \n\nRequest To Allow Repetitive Inspections Instead of Parts Replacement \n\n\tAnother commenter requests that we revise the proposed AD to allow operators to perform repetitive inspections for cracking of H-11 bolts, instead of replacement of the H-11 bolts. The commenter states that, according to the proposed AD and the referenced service bulletin, there are no reported failures of H-11 bolts. The commenter also states that Stage 3 noise requirements and the retirement of some Boeing Model 727 airplanes have significantly reduced the number of affected H-11 bolts. The commenter asserts that the replacement of H-11 bolts should not be a mandatory replacement, and that a revision to the maintenance program for inspection of the affected bolts would be sufficient for detecting cracking. \n\n\tWe do not agree for the same reasons as stated above. \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 1,148 Model 727 airplanes of the affected design in the worldwide fleet. The FAA estimates that 715 Model 727 airplanes of U.S. registry will be affected by this AD, that it will take approximately 3 work hours per airplane to accomplish the required inspection, and that the average labor rate is $65 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $139,425, or $195 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\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: