Discussion \n\n\n\tWe issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to the specified products. The NPRM published in the Federal Register on March 7, 2013 (78 FR 14731). The NPRM proposed to require repetitive inspections of the longeron extension fittings for cracking, and corrective actions if necessary. \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 proposal (78 FR 14731, March 7, 2013) and the FAA's response to each comment. \n\tUnited Airlines (UAL) did not have any technical comments regarding the NPRM (78 FR 14731, March 7, 2013). \n\nRequest to Change Applicability \n\n\n\tUPS and Virgin Atlantic Airways (VIR) stated that airplane line numbers 1199 through 1419 inclusive are included in the effectivity of Boeing Alert Service Bulletin 747-53A2860, dated December 4, 2012, and that the applicabilityof the NPRM (78 FR 14731, March 7, 2013) includes airplane line numbers 1076 through 1419 inclusive. The commenters noted that Boeing Alert Service Bulletin 747-53A2860, dated December 4, 2012, does not provide inspection or repair instructions for airplanes with line numbers prior to 1199. UPS requested that paragraph (c), ''Applicability,'' in the NPRM be revised to match the effectivity included in the Boeing service information. We infer that VIR made the same request. \n\tBoeing requested that changes be made to paragraph (c), ''Applicability,'' and paragraph (i)(3), ''Exceptions to Service Bulletin Specifications,'' of the NPRM (78 FR 14731, March 7, 2013), in regard to the applicability. Boeing noted that line number 1076, included in paragraph (c), ''Applicability,'' does not align with any production line changes and the line numbers should be changed from 1076 through 1419 inclusive to 1097 through 1419 inclusive. \n\tBoeing stated that paragraph (i)(3) of the NPRM (78 FR 14731, March 7, 2013) should be revised to clearly define the applicable airplanes because, as written, it could be interpreted to include more than the appropriate airplanes. Boeing requested that paragraph (i)(3) of the NPRM be revised to state ''For airplanes not identified in Boeing Alert Service Bulletin 747-53A2860, dated December 4, 2012, but are included in paragraph (c) of this AD: These airplanes are in Group 1 of the subject service bulletin for the purposes of this AD and are required to do the applicable actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2860, dated December 4, 2012.'' \n\tWe agree with Boeing's position regarding paragraphs (c) and (i)(3) of this final rule. We had conservatively established the applicability as starting at line number 1076 based on the information available at the time the NPRM (78 FR 14731, March 7, 2013) was issued. Since that time, Boeing has determined that the manufacturing change started at linenumber 1097. Boeing advised that Boeing Alert Service Bulletin 747-53A2860, dated December 4, 2012, will be revised and the effectivity in that service bulletin will be changed to start with line number 1097. Based on this information, we revised paragraph (c) in this final rule to include line numbers 1097 through 1419 inclusive. We revised paragraph (i)(3) in this final rule to include text similar to that proposed by Boeing. \n\tWe do not agree with UPS and VIR that the applicability of this final rule should match the effectivity in Boeing Alert Service Bulletin 747-53A2860, dated December 4, 2012. As stated previously, Boeing advised us that Boeing Alert Service Bulletin 747-53A2860, dated December 4, 2012, will be revised and the effectivity in the revised service bulletin will start with line number 1097. We have not changed this final rule in this regard. \n\nRequest to Clarify the Difference in the Line Numbers Between the Service Information and the NPRM (78 FR 14731, March 7, 2013) \n\n\n\tBoeing requested changes to the Discussion section of the NPRM (78 FR 14731, March 7, 2013) to clarify the differences between the airplane line numbers (1199 through 1419 inclusive) identified in Boeing Alert Service Bulletin 747-53A2860, dated December 4, 2012, and the airplane line numbers (1076 through 1419 inclusive) identified in paragraph (c) of the NPRM (78 FR 14731, March 7, 2013). Boeing stated that, after the release of Boeing Alert Service Bulletin 747-53A2860, dated December 4, 2012, a crack was reported on airplane line number 1101 and that the longeron extension fitting had been redesigned at line number 1097. \n\tBoeing suggested that the text ''. . . Subsequent analysis by Boeing indicated that the cracks were caused by fatigue combined with preload stress from improper fit-up during assembly. A manufacturing process change that began at line number 1199 might have resulted in preloading the longeron extension fittings . . .'' be changed to ''Subsequent review by Boeing has shown that the reported cracking correlates with this design change made at line number 1097.'' \n\tWe agree that the suggestions made by Boeing provide a more accurate description of how the affected line numbers were determined; however, this information is not restated in the Discussion section of this final rule, so no change is needed. The line numbers were changed from 1076 through 1419 inclusive to 1097 through 1419 inclusive in paragraph (c), ''Applicability,'' of this final rule, as explained previously. \n\nConcern Regarding Parts Availability \n\n\n\tUAL stated that Boeing Alert Service Bulletin 747-53A2860, dated December 4, 2012, does not include price and supply data for replacement longeron fittings. UAL asked if operators are expected to fabricate these replacement fittings. UAL noted that, if operators do not have the capabilities to fabricate fittings, it could be difficult for those operators to get parts. \n\tWe acknowledge the commenter's concern regarding the availability of replacement longeron fittings. Boeing Alert Service Bulletin 747- 53A2860, dated December 4, 2012, lists other available options as alternatives to replacing longeron extension fittings. The availability of required parts was considered when developing the compliance time for this AD. We have \n\n((Page 43765)) \n\ncontacted Boeing regarding parts availability and Boeing responded that parts are available. Longeron extension fittings are a one piece forging and operators are not expected to fabricate these fittings. We have not changed this final rule 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 this 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 NPRM (78 FR 14731, March 7, 2013) for correcting the unsafe condition; and \n\tDo not add any additional burden upon the public than was already proposed in the NPRM (78 FR 14731, March 7, 2013). \n\tWe also determined that these changes will not increase the economic burden on any operator or increase the scope of this AD. \n\nCosts of Compliance \n\n\n\tWe estimate that this AD affects 41 airplanes of U.S. registry. \n\tWe estimate the following costs to comply with this AD: \n\n\n\tEstimated Costs ---------------------------------------------------------------------------------------------------------------- \n\tCost per \n\tAction Labor cost Parts cost product Cost on U.S. operators ---------------------------------------------------------------------------------------------------------------- High frequency eddy current 32 work-hours x $85 $0 $2,720 $111,520, per inspection \n\tinspection for cracking in per hour = $2,720, cycle. \n\tlongeron extension fittings. per inspection cycle. Option to do preventative 479 work-hours x $85 0 40,715 $1,669,315. \n\tmodification instead of per hour = $40,715. \n\trepetitive inspections. ---------------------------------------------------------------------------------------------------------------- \n\n\n\tWe estimate the following costs to do any necessary replacements that would be required based on the results of the inspection. We have no way of determining the number of aircraft that might need this replacement: \n\n\n\tOn-Condition Costs ------------------------------------------------------------------------ \n\tCost per \n\tAction Labor cost Parts cost product ------------------------------------------------------------------------ Replacement........... 464 work-hours x $0 $39,440 \n\t$85 per hour = \n\t$39,440. ------------------------------------------------------------------------ \n\n\n\tWehave received no definitive data that would enable us to provide cost estimates for the on-condition actions specified in this AD. \n\tAccording to the manufacturer, some of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected individuals. We do not control warranty coverage for affected individuals. As a result, we have included all costs in our cost estimate. \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.