Examining the Docket \n\n\tYou may examine the airworthiness directive (AD) docket on the Internet at http://dms.dot.gov or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the street address stated in the ADDRESSES section. \n\nDiscussion \n\n\tThe FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to certain Boeing Model 737-600, -700, -700C, and -800 series airplanes. That NPRM was published in the Federal Register on November 24, 2004 (69 FR 68268). That NPRM proposed to require inspecting/measuring the length of the attachment fasteners between the nacelle support fittings and the lower wing skin panels, and related investigative/corrective actions if necessary. \n\nComments \n\n\tWe provided the publicthe opportunity to participate in the development of this AD. We have considered the comments received. \n\nSupport for the NPRM \n\n\tOne commenter supports the actions described in the NPRM. \n\nNotice of Service Bulletin Revision \n\n\tOne commenter, the manufacturer, notes that there is an error in the variable numbers listed in the effectivity of Boeing Service Bulletin 737-57-1275, dated September 4, 2003 (which was referenced as the appropriate source of service information for accomplishing the proposed actions). The commenter states that this error is corrected in the next revision of the service bulletin and that correcting this error in the service bulletin will not alter the NPRM's applicability. \n\n\tWe agree with the commenter that the applicability of this AD is not affected by the change in variable numbers. The applicability of this AD refers to the airplane line numbers and not to the variable numbers. \n\n\tSince the issuance of the NPRM, Boeing has issued Service Bulletin 737-57-1275, Revision 1, dated August 18, 2005, which contains the same procedures as the original issue along with the corrected variable numbers. Revision 1 of the service bulletin also divides the effectivity into four groups in order to provide clarification on the different fastener installation configurations. We have revised this AD to reference Revision 1 as the appropriate source of service information for accomplishing the required actions. We have also added paragraph (h) to this AD to give credit for actions done before the effective date of this AD in accordance with the original issue of the service bulletin. \n\nClarification of Sealant Specification \n\n\tOne commenter notes that Figures 1 and 2 of Boeing Service Bulletin 737-57-1275, dated September 4, 2003, specify an obsolete sealant. The commenter states that the "Parts and Materials Supplied by the Operator" section of the service bulletin specifies to refer to the Qualified Parts List (QPL) at the end of the Boeing Material Specification (BMS) for supplier data; however, there is no QPL for BMS 5-26 because it is obsolete. The commenter points out that BMS 5-45 has superseded BMS 5-26. \n\n\tWe agree with the commenter that BMS 5-45 is the correct specification for the sealant. Boeing Service Bulletin 737-57-1275, Revision 1, dated August 18, 2005, does contain the correct references to BMS 5-45. As stated previously, we have revised this AD to reference Revision 1 as the appropriate source of service information for accomplishing the required actions. No further work is necessary for airplanes on which Boeing Service Bulletin 737-57-1275, dated September 4, 2003, was accomplished. \n\nRequest To Revise Compliance Time \n\n\tOne commenter requests that we revise the compliance time specified in paragraph (f)(2) of the NPRM from prior to the accumulation of "30,000 flight cycles or 30,000 flight hours, whichever is first" to prior to the accumulation of "30,000 flight cycles or 37,000 flight hours, whichever is first." The commenter states that 15 of its airplanes are not scheduled for a heavy "C" check maintenance within the 30,000-flight-hour window and the proposed compliance time would result in unnecessary financial hardship. No technical justification was provided. \n\n\tWe do not agree with the commenter to revise the compliance time. In developing an appropriate compliance time, we considered the safety implications, the manufacturer's recommendation, and normal maintenance schedules for timely accomplishment of the inspection. We have determined that the compliance time, as proposed, represents the maximum interval of time allowable for the affected airplanes to continue to safely operate before the inspection is done. However, paragraph (i) of this AD provides affected operators the opportunity to apply for an adjustment of the compliance time if the operator also presents data that justify the adjustment. We have not revised this AD in this regard. \n\nExplanationof Change Made to This AD \n\n\tBoeing Commercial Airplanes has received a Delegation Option Authorization (DOA). We have revised this AD to delegate the authority to approve an alternative method of compliance for any repair required by this AD to an Authorized Representative for the Boeing Commercial Airplanes DOA rather than a Designated Engineering Representative (DER). \n\nClarification of Alternative Method of Compliance (AMOC) Paragraph \n\n\tWe have revised this AD to clarify the appropriate procedure for notifying the principal inspector before using any approved AMOC on any airplane to which the AMOC applies. \n\nConclusion \n\n\tWe have carefully reviewed the available data, including the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously. We have determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCosts of ComplianceThere are about 751 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this AD. \n\n\tEstimated Costs \n\n\nAction \nWork hours \nAverage labor rate per hour \nParts \nCost per airplane \nNumber of U.S.-\nregistered airplanes \nFleet cost \nInspection/Measurement \n12 \n$65 \nNominal \n$780 \n302\n $235,560 \n\n\nAuthority for This Rulemaking \n\n\tTitle 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority. \n\n\tWe are issuing this rulemaking under the authority described in subtitle VII, part A, subpart III, section 44701, "General requirements." Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. \n\nRegulatory Findings \n\n\tWe have determined that this AD will not have federalism implications under Executive Order 13132. This AD 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. \n\n\tFor the reasons discussed above, I certify that this AD: \n\n\t(1) Is not a "significant regulatory action" under Executive Order 12866; \n\n\t(2) Is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and \n\n\t(3) Will not have a significant economic impact, positive or negative, on a substantial number of small entitiesunder the criteria of the Regulatory Flexibility Act. \n\n\tWe prepared a regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation. \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, under the authority delegated to me by the Administrator, the FAA amends 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\nSec. 39.13 (Amended) \n\n2. The Federal Aviation Administration (FAA) amends Sec. 39.13 by adding the following new airworthiness directive (AD):