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 September 24, 2012 (77 FR 58791). The NPRM proposed to require revising the maintenance program to update inspection requirements to detect fatigue cracking of PSEs. \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 (77 FR 58791, September 24, 2012) and the FAA's response to each comment. \n\nRequests To Use the Most Recent MPD Document \n\n\n\tBoeing and American Airlines (AAL) requested that the most recent MPD document be incorporated into the NPRM (77 FR 58791, September 24, 2012). \n\tBoeing stated that the NPRM (77 FR 58791, September 24, 2012) should reference Subsection B, AWLs--Structural Inspections, of Section 9, ''Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs),'' of Boeing 737-600, -700, -700C, -800, -900, and -900ER MPD Document, D626A001-CMR, Revision December 2011. Boeing stated that this is the most recent MPD document and that this revision incorporates more stringent restrictions that should be included before the final rule is issued. \n\tAAL stated that the Relevant Service Information section and paragraph (g) of the NPRM (77 FR 58791, September 24, 2012) refer to Subsection B, AWLs--Structural Inspections, of Section 9, ''Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs),'' of Boeing 737-600, -700, -700C, -800, -900, and -900ER MPD Document, D626A001-CMR, Revision July 2011. AAL stated that the most recent revision of that document is Revision August 2012, and that it should be incorporated into the NPRM. \n\tWe agree with the commenters' requests. The Relevant Service Information section of the NPRM (77 FR 58791, September 24, 2012) is not restated in the final rule. However, we have added both Revision December 2011 and Revision August 2012 of Subsection B, AWLs-- Structural Inspections, of Section 9, ''Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs),'' of Boeing 737-600, -700, -700C, -800, -900, and -900ER MPD Document, D626A001-CMR to paragraph (g) of this AD as acceptable options for doing the actions required by this AD. We also re-organized paragraph (g) of this AD to improve readability. Because Revision August 2012 of Subsection B, AWLs--Structural Inspections, of Section 9, ''Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs),'' of Boeing 737-600, -700, -700C, -800, -900, and -900ER MPD Document, D626A001-CMR is a more stringent document, we might consider future rulemaking to require the actions specified in that document. \n\nRequest To Use Later Revisions of the Service Information \n\n\n\tAll Nippon Airways (ANA) requested the use of a later-approved MPD document. ANA noted that the NPRM (77 FR 58791, September 24, 2012) refers to Subsection B, AWLs--Structural Inspections, of Section 9, ''Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs),'' of Boeing 737-600, -700, -700C, -800, -900, and -900ER MPD Document, D626A001-CMR, Revision July 2011, and that the current document is Revision December 2011. ANA stated that once the NPRM becomes a final rule, an alternative method of compliance (AMOC) will be necessary to do the actions in the latest document. ANA also stated that airworthiness limitations and CMR documents are revised periodically; if an AMOC is necessary for each revision of the document, it will burden the operators. ANA stated that if paragraph (g) of the NPRM addresses ''D626A001-CMR revision July 2011, or later,'' then an AMOC will not be necessary for each later revision of the document. ANA stated that, since the document is reviewed by the FAA prior to public release, the FAA is able to confirm if the document meets the adequate level of safety. \n\tWe disagree with ANA's request. We cannot use the phrase, ''or later FAA-approved revisions,'' in an AD when referring to the service document because doing so violates Office of the Federal Register (OFR) regulations for approval of materials ''incorporated by reference'' in rules. See 1 CFR 51.1(f). \n\tIn general terms, we are required by OFR regulations to either publish the service document contents as part of the actual AD language; or submit the service document to the OFR for approval as ''referenced'' material, in which case we may only refer to such material in the text of an AD. The AD may refer to the service document only if the OFR approved it for ''incorporation by reference.'' See 1 CFR part 51. \n\tTo allow operators to use later revisions of the referenced document (issued after publication of the AD), either we must revise the AD to reference specific later revisions, or operators must request approval to use later revisions as an AMOC with this AD under the provisions of paragraph (j)(1) of this AD. As stated previously, we have added Revision December 2011 \n\n((Page 61175)) \n\nand Revision August 2012 of Subsection B, AWLs--Structural Inspections, of Section 9, ''Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs),'' of Boeing 737-600, -700, -700C, - 800, -900, and -900ER MPD Document, D626A001-CMR to paragraph (g) of this AD as acceptable options for doing the required actions. \n\nRequests for an AMOC Exception \n\n\n\tWestJet and AAL requested an AMOC exception. \n\tWestJet stated that in paragraph (c)(2) of the NPRM (77 FR 58791, September 24, 2012) the wording ''may not be able to'' implies that if an inspection to a modified, altered, or repaired area can be accomplished, then an AMOC is not required. WestJet also stated that an AMOC should not be required for Boeing repairs that have damage tolerant assessments and for supplemental type certificates(STCs) that have FAA-approved airworthiness limitation structural inspections. \n\tAAL stated that paragraph (c)(2) of the NPRM (77 FR 58791, September 24, 2012) provides minimal information on how operators should address new and existing repairs in a PSE area, as defined in Subsection B, AWLs--Structural Inspections, of Section 9, ''Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs),'' of Boeing 737-600, -700, -700C, -800, -900, and -900ER MPD Document, D626A001-CMR, Revision July 2011. AAL also stated that all repairs in a PSE area that hide a portion of the inspection area will need an alternate inspection method approved by the Seattle Aircraft Certification Office to ensure continued damage tolerance of the affected structure. AAL stated that the current process will create an unnecessary burden on operators. AAL said that repairs approved under section 25.571(b) or 26.43(d) of the Federal Aviation Regulations (14 CFR 25.571(b) and 14 CFR 26.43(d),respectively) would provide the required level of safety for the continued damage tolerance of the affected structure for the NPRM. \n\tWe disagree with the commenters' requests. The revised set of inspections in Subsection B, AWLs--Structural Inspections, of Section 9, ''Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs),'' of Boeing 737-600, -700, -700C, -800, -900, and -900ER MPD Document, D626A001-CMR, Revision July 2011, resulted from an updated analysis of The Boeing Company Model 737-600, -700, -700C, - 800, -900, and -900ER series airplanes. The analysis includes consideration of updated loads and flight lengths that increase the stresses on the structure. Previously approved repairs, modifications, and alterations may not include consideration of the updated analysis, and therefore, a review is required before an AMOC can be issued for them. Affected operators, however, may request approval of an AMOC under the provisions of paragraph (j)(1) ofthis AD by submitting data substantiating that the change would provide an acceptable level of safety. We have not changed this final rule in this regard. \n\nRequest To Reference Different Advisory Circular (AC) \n\n\n\tAAL requested that the NPRM (77 FR 58791, September 24, 2012) reference a different AC. AAL stated that paragraph (c)(2) of the NPRM provides FAA guidance for determining the changes necessary for the required inspections to satisfy the continued damage tolerance of the affected structure. AAL stated that the NPRM references FAA AC 25.1529- 1A, dated November 20, 2007 (http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2025.1529-1A.pdf), for guidance regarding alternative inspection procedures; however, AC 25.1529-1A, dated November 20, 2007, applies only to airplanes that have a passenger seating capacity of less than 30 and a maximum payload capacity of less than 7,500 pounds. AAL stated that FAA AC 120-93, dated November 20, 2007 (http://rgl.faa.gov/Regulatory--and--Guidance--Library/ rgAdvisoryCircular.nsf/0/f73fd2a31b353a71862573b000521928/$FILE/ AC%20120-93.pdf), refers to the damage tolerance inspection for repairs and alteration. \n\tWe agree with the commenter's request. We have revised paragraph (c)(2) of this AD by specifying FAA AC 120-93, dated November 20, 2007 (http://rgl.faa.gov/Regulatory--and--Guidance--Library/ rgAdvisoryCircular.nsf/0/f73fd2a31b353a71862573b000521928/$FILE/ AC%20120-93.pdf), in lieu of FAA AC 25.1529-1A, dated November 20, 2007 (http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2025.1529-1A.pdf.) \n\nSTC Comment \n\n\n\tAviation Partners Boeing stated that the installation of winglets per STC ST00830SE (http://rgl.faa.gov/Regulatory--and--Guidance-- Library/rgstc.nsf/0/408e012e008616a7862578880060456c/$FILE/ ST00830SE.pdf) affects the accomplishment of the manufacturer's service instructions. \n\tWe have added paragraph (c)(3) of this AD to state that installation of STC ST00830SE (http://rgl.faa.gov/Regulatory--and-- Guidance--Library/rgstc.nsf/0/408e012e008616a7862578880060456c/$FILE/ ST00830SE.pdf) affects the ability to accomplish the actions required by this AD. Therefore, for airplanes on which STC ST00830SE is installed, a ''change in product'' AMOC approval request might be necessary to comply with the requirements of 14 CFR 39.17. \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 (77 FR 58791, September 24, 2012) for correcting the unsafe condition; and \n\tDo not add any additional burden upon the public than was already proposed in the NPRM (77 FR 58791, September 24, 2012). \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 1,200 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 ---------------------------------------------------------------------------------------------------------------- Document Revision........................ 1 work-hour x $85 per hour $0 $85 $102,000 \n\t= $85. ---------------------------------------------------------------------------------------------------------------- \n\n\n\n((Page 61176)) \n\nPaperwork Reduction Act \n\n\n\tA federal agency may not conduct or sponsor, and a person is not required to respond to, nor shall a person be subject to a penalty for failure to comply with a collection of information subject to the requirements of the Paperwork Reduction Act unless that collection of information displays a current valid OMB Control Number. The OMB Control Number for this information collection is 2120-0056. Public reporting for this collection of information is estimated to be approximately 5 minutes per response, including the time for reviewing instructions, completing and reviewing the collection of information. All responses to this collection of information are mandatory. Comments concerning the accuracy of this burden and suggestions for reducing the burden should be directed to the FAA at: 800 Independence Ave. SW., Washington, DC 20591, Attn: Information Collection Clearance Officer, AES-200. \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.