Discussion \n\n\n\tWe issued a supplemental notice of proposed rulemaking (SNPRM) to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to the specified products. That SNPRM published in the Federal Register on March 16, 2012 (77 FR 15638). The original NPRM (74 FR 15683, April 7, 2009) proposed to require modifying the fluid drain path in the wing leading edge area, forward of the wing front spar and doing all applicable related investigative and corrective actions. The SNPRM proposed to revise that NPRM by including installing new seal disks on the latches in the fuel shutoff valve access door as part of the modification and by specifying that certain inspections are detailed inspections. The SNPRM also proposed to revise the applicability to include additional airplanes. \n\nRevised Service Bulletin \n\n\n\tBoeing has issued Special Attention Service Bulletin 737-57-1293, Revision 3, dated December 14, 2012. This revision includes clarification for the re-identification of parts and assemblies. We have revised paragraphs (c) and (g) of this AD to refer to Boeing Special Attention Service Bulletin 737-57-1293, Revision 3, dated December 14, 2012. \n\n((Page 25378)) \n\nComments \n\n\n\tWe gave the public the opportunity to participate in developing this AD. The following presents the comments received on the supplemental NPRM (77 FR 15638, March 16, 2012) and the FAA's response to each comment. \n\nConcurrence \n\n\n\tBoeing concurred with the content of the SNPRM (77 FR 15638, March 16, 2012). \n\nRequest for Compliance Time Extension \n\n\n\tUnited Airlines, Tracinda Flight Department, and American Airlines requested an extension to the 24-month compliance time specified in the SNPRM (77 FR 15638, March 16, 2012). Tracinda Flight Department requested a compliance time of 36 months to coincide with a heavy maintenance check. American Airlines requested a compliance time of 60 to 72 months to coincide with its scheduled heavy maintenance check. American Airlines stated that the actions accomplished in accordance with AD 2011-06-05, Amendment 39-16629 (76 FR 15808, March 22, 2011), address the safety issue identified in the SNPRM. United Airlines recommended a compliance time of 60 months for airplanes on which actions have been done in accordance with AD 2011-06-05, as well as airplanes having line numbers 2700 and subsequent on which the actions have been incorporated for the wing slat down stop hardware modification and inspections. \n\tWe disagree with the commenters' requests to extend the compliance time. 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 modification is done. Since maintenance schedules vary among operators, there would be no assurance that the airplanes would be modified during that maximum interval. However, under the provisions of paragraph (i) of the final rule, we will consider requests for approval of an extension of the compliance time if sufficient data are submitted to substantiate that a new compliance time would provide an acceptable level of safety. Additionally, the issue addressed in this AD is different from the issue addressed in AD 2011-06-05, Amendment 39-16629 (76 FR 15808, March 22, 2011); therefore, changing the compliance time based on the actions done in accordance with AD 2011-06-05 is not acceptable. We have not changed the AD in this regard. \n\nRequest for Change to Airplane Groups \n\n\n\tSouthwest Airlines requested a change to the airplanes in Group 2, as specified in Boeing Special Attention Service Bulletin 737-57-1293, Revision 2, dated September 28, 2011. The commenter stated that Group 2 airplanes include line numbers 2131 through 2837--instead of 2131 through 2437, as specified in Boeing Special Attention Service Bulletin 737-57-1293, Revision 2, dated September 28, 2011. The commenter stated that Figures 4 and 16 of that service bulletin specify a modification of the hinge assembly having part number (P/N) 116A5522-1, which is installed on airplanes having line numbers 1 through 2837. \n\tWe disagree to change the airplanes in Group 2. The purpose of the Group 2 division is to address a parting agent issue and not hinge trimming. Although the hinge assembly part number does change at airplane line number 2837, it is unrelated to the Group 2 division. No change has been made to the AD in this regard. \n\nRequest for Parts Specifications \n\n\n\tAmerican Airlines requested that we provide material specifications and part dimensions to allow for manufacturing of alternatives for a seal disk having P/N 116A8505-2. The commenter stated that the parts are unavailable from Boeing and having an alternate part is necessary to ensure a sufficient supply for operators. \n\tWe cannot include proprietary information such as part dimensions and materials in ADs; however, we are aware that seal disks having P/N 116A8505-2 are now available from the manufacturer. No change has been made to the AD in this regard. \n\nRequest for Credit for Actions Done Previously \n\n\n\tTracinda Flight Department requested that we revise the supplemental NPRM (77 FR 15638, March 16, 2012) to provide credit for doing the actions specified in Boeing Special Attention Service Bulletin 737-57-1293, Revision 2, dated September 28, 2011. \n\tWe agree to allow credit for actions done in accordance with Boeing Special Attention Service Bulletin 737-57-1293, Revision 2, dated September 28, 2011. We have added new paragraph (h) to this AD accordingly. \n\tAmerican Airlines requested that we revise the supplemental NPRM (77 FR 15638, March 16, 2012) to allow credit for actions done using Boeing Special Attention Service Bulletin 737-57-1293, Revision 1, dated January 11, 2010. The commenter stated that the updates in Boeing Special Attention Service Bulletin 737-57-1293, Revision 2, dated September 28, 2011, do not address the safety issue with the exception of the addition of the rubber seal disk. \n\tWe disagree with the commenter's request. Boeing Special Attention Service Bulletin 737-57-1293, Revision 2, dated September 28, 2011, changed the inspection type for the bonding jumper countersink diameter and clarified certain instructions specified in Boeing Special Attention Service Bulletin 737-57-1293, Revision 1, dated January 11, 2010. However, operators may request approval of an alternative method of compliance (AMOC), as specified in paragraph (i) of this AD. No change has been made to the AD in this regard. \n\nConclusion \n\n\n\tWe reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting the AD with the changes described previously and minor editorial changes. We have determined that these minor changes: \n\tAre consistent with the intent that was proposed in the SNPRM (77 FR 15638, March 16, 2012) for correcting the unsafe condition; and \n\tDo not add any additional burden upon the public than was already proposed in the SNPRM (77 FR 15638, March 16, 2012). \n\tWe also determined that these changes will not increase the economic burden on any operator or increase the scope of the AD. \n\nCosts of Compliance \n\n\n\tWe estimate that this AD affects 1,072 airplanes of U.S. registry. \n\tWe estimate the following costs to comply with this AD: \n\n\n\tEstimated Costs ---------------------------------------------------------------------------------------------------------------- \n\tCost per Cost on U.S. \n\tAction Labor cost Parts cost product operators ---------------------------------------------------------------------------------------------------------------- Modification, Group 1 (734 airplanes) 50 work-hours x $85 per $1,262 $5,512 $4,045,808 \n\thour = $4,250. \n\n((Page 25379)) \n\n\n\nModification, Group 2 (58 airplanes). 27 work-hours x $85 per 1,262 3,557 206,306 \n\thour = $2,295. Modification, Group 3 (280 airplanes) 3 work-hours x $85 per 94 349 97,720 \n\thour = $255. ---------------------------------------------------------------------------------------------------------------- \n\nAuthority for This Rulemaking \n\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\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\n\tThis 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\tFor the reasons discussed above, I certify that this AD: \n\t(1) Is not a ''significant regulatory action'' under Executive Order 12866, \n\t(2) Is not a ''significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), \n\t(3) Will not affect intrastate aviation in Alaska, and \n\t(4) 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. \n\nList of Subjects in 14 CFR Part 39 \n\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.