Discussion \n\n\n\tWe issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2008-18-07, Amendment 39-15664 (73 FR 56960, October 1, 2008). AD 2008-18-07 applies to certain The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, and 747SR series airplanes. The NPRM published in the Federal Register on May 8, 2013 (78 FR 26720). The NPRM was prompted by a report of a cracked reveal made from a casting found within a group of airplanes that should have machined reveals made only from 6061 aluminum. The NPRM proposed to retain all the requirements of AD 2008-18-07. The NPRM also proposed to add, for certain airplanes, an inspection to determine the material of the number 3 MED corner reveal, repetitive inspections for cracking of 6061 machined aluminum one-piece corner reveals, and replacement with 6061 machined aluminum two-piece corner reveals if necessary, which terminates certain repetitive inspections. We are issuing this AD to detect and correct fatigue cracking of the lower forward corner reveal of the number 3 MEDs, which could lead to the door escape slide departing the airplane when the door is opened and the slide is deployed, and consequent injuries to passengers and crew using the door escape slide during an emergency evacuation. \n\nRelated AD \n\n\n\tAD 2008-18-07, Amendment 39-15664 (73 FR 56960, October 1, 2008), requires, for The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, and 747SR series airplanes, an inspection to determine the material of a number 3 MED corner reveal, repetitive inspections of certain reveals for cracking, a detailed inspection of certain reveals for a sharp edge and cracking, and corrective action if necessary. AD 2008-18-07 allows reveal replacement as an option to certain inspections. AD 2008-18-07 was prompted by reports of cracking and/or a sharp edge in the lower forward corner reveal of the number 3 MEDs. AD 2008-18-07 refers to Boeing Special Attention Service Bulletin 747-53-2460, Revision 1, dated February 13, 2007, as the appropriate source of service information for the required actions specified in that AD. \n\nExplanation of Difference in Requirements Between the NPRM (78 FR 26720, May 8, 2013) and This Final Rule \n\n\n\tIn the NPRM (78 FR 26720, May 8, 2013), the FAA proposed to supersede AD 2008-18-07, Amendment 39-15664 (73 FR 56960, October 1, 2008), to reflect the changes in airplane groups specified in revised service information, Boeing Special Attention Service Bulletin 747-53- 2460, Revision 2, dated December 22, 2010. However, based on the comments received on the NPRM, it became evident that it was difficult to follow the numerous changes between Boeing Special Attention Service Bulletin 747-53-2460, Revision 1, dated February 13, 2007, and Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December22, 2010, as well as in following the corresponding actions specified in the NPRM. \n\tThere are only two significant changes in Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010: (1) Airplanes having line numbers 1038 through 1270 were moved from Group 2 to Group 4; and (2) for Group 4 airplanes, there are additional actions. Therefore, for clarity, we have determined that a less burdensome approach is to revise this final rule to include only the new actions for Group 4 airplanes. Instead of superseding AD 2008-18- 07, Amendment 39-15664 (73 FR 56960, October 1, 2008), this final rule is a stand-alone AD, applicable \n\n((Page 77380)) \n\nonly to Group 4 airplanes as identified in Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, except for those airplanes that have been converted to an all-cargo configuration. Airplanes identified in the applicability of AD 2008-18- 07 are still required to continue tocomply with the requirements of that AD. \n\tSince this AD does not supersede AD 2008-18-07, Amendment 39-15664 (73 FR 56960, October 1, 2008), paragraphs (g) through (m), (p), (q), and (v) of the NPRM (78 FR 26720, May 8, 2013) are not included in this AD. Also, the corresponding paragraph identifiers have been redesignated in this final rule, as listed in the following table: \n\n\n\tRedesignated Paragraph Identifiers ------------------------------------------------------------------------ Requirement in the proposed AD (78 \n\tFR 26720, May 8, 2013) Corresponding requirement in this AD ------------------------------------------------------------------------ \n\tparagraph (t) paragraph (g). \n\tparagraph (s) paragraph (h). \n\tparagraph (r) paragraph (i). \n\tparagraph (u) paragraph (j). \n\tparagraph (n) paragraph (k). \n\tparagraph (o) paragraph (l).paragraph (w) paragraph (n). ------------------------------------------------------------------------ \n\n\n\tWe have also revised paragraphs (n) and (o) of the proposed AD (78 FR 26720, May 8, 2013) (redesignated as paragraphs (k) and (l) of this AD) that referred to ''AD 2008-18-07.'' In paragraphs (k) and (l) of this AD, we have referred to the current service information, Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, instead of AD 2008-18-07, Amendment 39-15664 (73 FR 56960, October 1, 2008), for the locations where cast 356 aluminum reveals and machined 6061 aluminum reveals may not be installed. Paragraphs (k) and (l) of this AD state that the parts installation prohibition ends the parts installation prohibitions specified in paragraphs (n) and (o) of AD 2008-18-07, Amendment 39-15664 (73 FR 56960, October 1, 2008). \n\nComments \n\n\n\tWe gave the public the opportunity to participate in developing this AD. Thefollowing presents the comments received on the NPRM (78 FR 26720, May 8, 2013) and the FAA's response to each comment. \n\nRequest To Clarify the Cause of the Unsafe Condition \n\n\n\tBoeing asked that we clarify the cause of the unsafe condition identified in paragraph (e) of the proposed AD (78 FR 26720, May 8, 2013). Boeing stated that the report that prompted the proposed supersedure of AD 2008-18-07, Amendment 39-15664 (73 FR 56960, October 1, 2008), involved a cracked casting on an airplane that should have machined reveals made from only 6061 aluminum. \n\tWe agree that the unsafe condition should be clarified for the reason provided. We have changed the wording for the unsafe condition identified in the SUMMARY section and in paragraph (e) of this final rule to specify that ''This new AD was prompted by a report of a cracked reveal made from a casting found within a group of airplanes that should have machined reveals made only from 6061 aluminum.'' We have also clarified the Discussion section of this final rule to specify that the NPRM (78 FR 26720, May 8, 2013) was prompted by that report. \n\nRequest To Revise Wording in the NPRM (78 FR 26720, May 8, 2013) \n\n\n\tBoeing requested numerous changes related to the wording in paragraphs (g), (h), (j), (u) and (v) of the NPRM (78 FR 26720, May 8, 2013). \n\tWe acknowledge the commenter's concerns for clarity. However, as stated previously, this AD does not supersede AD 2008-18-07, Amendment 39-15664 (73 FR 56960, October 1, 2008). The changes requested by the commenter referred to the ''retained'' paragraphs of AD 2008-18-07, which are not restated in this AD; therefore, no action is necessary in this regard. \n\nRequest To Revise Service Information \n\n\n\tDelta Airlines (Delta) requested that Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, be revised prior to the issuance of this final rule. Delta stated that paragraphs (r) and (s) of the proposed AD (78 FR 26720, May 8, 2013) (redesignated as paragraphs (i) and (h) of this AD) are clear and understandable; however, when Delta reviewed the required actions in Table 1 of Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, Delta was not able to clearly determine which conditions were linked with which actions. Delta stated that Boeing also agrees that the compliance tables of Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, should be clarified for operators' use. \n\tWe disagree with delaying this AD to wait for revised service information in light of the urgency of the identified unsafe condition. As Delta stated, the tables contained in Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, are complicated and could be misinterpreted; however, we have addressed this concern by specifying the requirements and clarifying the appropriate actions in paragraphs (h) and (i) of this AD.When the service information is revised, we might consider approving it as an alternative method of compliance (AMOC) for these actions. We have not changed this final rule in this regard. \n\nRequest To Address an Error in Service Information \n\n\n\tDelta stated that, in the last row under the ''Action'' column of Table 8 of paragraph 1.E., Compliance, of Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, there is a reference to ''Table 9,'' which does not exist. Delta stated that the correct paragraph reference is ''Paragraph 3.B., Part 2,'' as confirmed in Delta's correspondence with Boeing. Delta requested that Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, be revised prior to the issuance of this final rule, or that we address this error in this final rule, or, at a minimum, address this error in a global AMOC. \n\tWe partially agree. We disagree to wait for revised service information in light of the urgency of the identified unsafe condition. However, we agree that the reference to Table 9 in paragraph 1.E., Compliance, of Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, is incorrect. To address this error, we have added a new paragraph (m) in this AD to state that, where the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, specify a post-repair detailed inspection in accordance with Table 9, this AD requires a detailed inspection in accordance with paragraph 3.B., Part 2, of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010. When revised service information becomes available, we might consider approving it as an AMOC for the actions required by this AD. \n\nRequest To Revise the Proposed AD To Include an Inspection for a Sharp Edge for Group 4 Airplanes \n\n\n\tBoeing asked that we revise paragraph (r)(2) of the proposed AD (78 FR 26720, May 8, 2013) (redesignated as paragraph (i)(2) of this AD) to include an inspection for a potential sharp edge \n\n((Page 77381)) \n\ncommon to the reveal. Boeing stated that this inspection might be the first inspection performed and, therefore, it is possible that a sharp edge could be found on a machined reveal. \n\tWe do not agree to revise the wording of paragraph (i)(2) of this AD (designated as paragraph (r)(2) of the proposed AD (78 FR 26720, May 8, 2013)). Paragraph (i)(2) of this AD requires, for previously inspected Group 4 airplanes, a material-type inspection to determine if the corner reveal is a casting, and, if a casting is found, continued inspections or replacement of the reveal with a two-piece machined reveal. Castings do not have sharp edges. Group 4 airplanes that were not previously inspected or changed, that have corner reveals found not to be castings, require inspections for a sharp edge in paragraph (g)(2)of this AD. We have not changed this final rule in this regard. \n\nRequest for Alternative Corrective Action for Group 4 Airplanes \n\n\n\tBoeing asked that we revise paragraph (t)(1) of the proposed AD (78 FR 26720, May 8, 2013) (redesignated as paragraph (g)(1) of this AD) to allow a weld repair for a cracked reveal made from a casting on Group 4 airplanes. Boeing stated that this would allow operators to repair the casting if they cannot obtain a machined reveal. \n\tWe agree that paragraph (g)(1) of this AD should allow a weld repair as an alternative corrective action since this was a permitted action for Group 2 airplanes in AD 2008-18-07, Amendment 39-15664 (73 FR 56960, October 1, 2008). This alternative corrective action for Group 4 airplanes was contained in Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, but was inadvertently omitted in the proposed AD (78 FR 26720, May 8, 2013). Paragraph (t) of the NPRM is redesignated as paragraph (g) in this AD and we have revised paragraph (g)(1) by adding new paragraphs (g)(1)(i) and (g)(1)(ii) in order to allow a weld repair as an option to replacing the reveal if any cracking is found. In paragraph (g)(1)(ii) of this AD we specify repairing in accordance with Part 4 of Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010. The inspection for cracking specified in paragraph (g)(1) of this AD is to be repeated thereafter at intervals not to exceed 3,000 flight cycles until a new two-piece reveal is installed in accordance with the requirements of paragraph (g)(1)(i) of this AD. \n\nRequest To Reference Service Bulletin Information Notices or Revise Service Bulletin \n\n\n\tDelta requested that Boeing Service Bulletin Information Notice 747-53-2460 IN 03, dated March 24, 2011, be referenced as an approved deviation from Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010. Alternatively, Boeing requested that we delay the issuance of this final rule until Boeing revises Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, to incorporate the changes outlined in that information notice. \n\tWe partially agree. We agree that Boeing Service Bulletin Information Notice 747-53-2460 IN 03, dated March 24, 2011, contains acceptable information for the inspection and modification mandated in this AD. However, we disagree with delaying issuance of this final rule until revised service information becomes available. We have determined that to delay this final rule would be inappropriate, because the inspections of the number 3 MED reveals and corrective actions are needed to reduce the risk of the identified unsafe condition addressed in this AD. The information that Boeing Service Bulletin Information Notice 747-53-2460 IN 03, dated March 24, 2011, clarifies is for reference only and is not required to address the identified unsafe condition. When revisedservice information becomes available, we might consider approving it as an AMOC for the actions required by this AD. We have made no change to this AD in this regard. \n\nExplanation of Additional Changes Made to This Final Rule \n\n\n\tWe redesignated paragraphs (r) and (r)(2) of the NPRM (78 FR 26720, May 8, 2013) as paragraphs (i) and (i)(2) of this final rule and removed the phrase ''Boeing Special Attention Service Bulletin 747-53- 2460, Revision 2, dated December 22, 2010,'' from the initial compliance times listed in those paragraphs. In the proposed AD, we stated that the compliance times could be calculated from the most recent work performed in accordance with Boeing Special Attention Service Bulletin 747-53-2460, Revision 1, dated February 13, 2007; or Revision 2, dated December 22, 2010; but this would introduce an error in paragraph (i) of this AD since it would require operators to complete the inspections required by Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, for a second time, if the reference to Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, remained. \n\tParagraph (i)(1) of this final rule specifies inspections for cracking of any corner reveal found to be a one-piece or two-piece casting. Boeing Special Attention Service Bulletin 747-53-2460, Revision 2, dated December 22, 2010, provides inspection procedures for one-piece corner reveals, but not for the two-piece corner reveals. Because the inspection procedures for the two-piece corner reveals were not included in the service information, operators would have been unable to comply with the proposed requirement to inspect a two-piece corner reveal, and in this case would have been required to obtain approval of an alternative method of compliance for this inspection. We have therefore revised paragraph (i)(1) of this AD to provide the appropriate procedures for both scenarios. \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 26720, May 8, 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 26720, May 8, 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 166 airplanes of U.S. registry. \n\tWe estimate the following costs to comply with this AD: \n\n((Page 77382)) \n\n\n\n\n\n\n\tEstimated Costs ---------------------------------------------------------------------------------------------------------------- \n\tCost on U.S. \n\tAction Laborcost Parts cost Cost per product operators ---------------------------------------------------------------------------------------------------------------- Material type inspection and 14 work-hours x $85 $0 $1,190 per $197,540 per \n\tinspection for cracks. per hour = $1,190 inspection cycle. inspection cycle. \n\tper inspection \n\tcycle. ---------------------------------------------------------------------------------------------------------------- \n\n\n\tWe estimate the following costs to do any necessary on-condition actions that would be required based on the results of the inspections. We have no way of determining the number of aircraft that might need these actions: \n\n\n\tOn-Condition Costs ---------------------------------------------------------------------------------------------------------------- \n\tAction Labor cost Parts cost Cost per product ---------------------------------------------------------------------------------------------------------------- Corner reveal removal and replacement.. 17 work-hours x $85 per $9,525 $10,970 per inspection \n\thour = $1,445 per cycle. \n\tinspection cycle. ---------------------------------------------------------------------------------------------------------------- \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 forpractices, 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 asubstantial 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.