Discussion \n\n\tOn May 26, 2005, we issued AD 2005-12-04, amendment 39-14120 (70 FR 34313, June 14, 2005). That AD applies to certain Boeing Model 757-200, -200PF, and -200CB series airplanes. That AD requires repetitive inspections of the shim installation between the vertical flange and bulkhead, and repair if necessary. That AD resulted from reports of cracks, loose and broken bolts, and shim migration in the joint between the aft torque bulkhead and the strut-to-diagonal brace fitting. The actions specified in that AD are intended to detect and correct such cracks, loose and broken bolts, and shim migration, which could result in damage to the strut and consequent separation of the strut and engine from the airplane. \n\nActions Since AD Was Issued \n\n\tSince we issued that AD, we have received reports of cracking in the pylon under bolts that appear to be undamaged during the existing AD inspections. Although the cracking was underneath non-discrepant bolts, it was adjacent to bolts subject to AD 2005-12-04 that were loose for a period of time long enough to cause this cracking. \n\nOther Relevant Rulemaking \n\n\tOn May 25, 2004, we issued AD 2004-12-07, amendment 39-13666 (69 FR 33561, June 16, 2004), for certain Boeing Model 757 series airplanes. That AD requires, for certain airplanes, repetitive detailed inspections of certain aft bulkhead fasteners for loose or missing fasteners, and corrective action if necessary. That AD also requires, for certain other airplanes, a one-time detailed inspection of the middle gusset of the inboard side load fitting for proper alignment and realignment if necessary; a one-time eddy current inspection of certain fastener holes for cracking, and repair if necessary; and a detailed inspection of certain fasteners for loose or missing fasteners; and replacement with new fasteners if necessary. Accomplishing the actions specified in this AD terminates the requirements specified in paragraphs (b) and (c) of AD 2004-12-07. \n\nRelevant Service Information \n\n\tWe have reviewed Boeing Alert Service Bulletin 757-54A0047, Revision 3, dated June 27, 2007 (we referred to Boeing Service Bulletin 757-54A0047, Revision 1, dated March 24, 2005, as the appropriate source of service information for accomplishing the required actions specified in AD 2005-12-04). The alert service bulletin describes basically the same procedures (as required by AD 2005-12-04) for repetitive detailed inspections of the shim installation between the vertical flange and bulkhead and repair if necessary; however, the description of the actions has been revised. The alert service bulletin specifies to do repetitive inspections as follows: \n\n\tDo detailed inspections of the shim installations between the vertical flange and bulkhead to determine if there are signs of movement. \n\n\tDo detailed inspections of the four fasteners in the vertical flange to determine if there are signs of movement or if there are gapsunder the head or collar. \n\n\tDo detailed inspections of the fasteners that hold the strut to the horizontal flange of the strut-to-diagonal brace fitting to determine if there are signs of movement or if there are gaps under the head or collar. \n\n\tThe alert service bulletin specifies to do related investigative actions and repairs as follows: \n\n\tRepair the shim if cumulative movement is 0.50 inch or less. \n\n\tReplace the shim if cumulative movement is more than 0.50 inch and do the inspection and repair of the four critical fastener holes on the horizontal flange specified in Part IV of the alert service bulletin. \n\n\tIf any fastener is rejected, inspect the fastener hole for cracking and repair if necessary, increase the diameter of the hole, install oversize fasteners, and do the inspection and repair of the four critical fastener holes on the horizontal flange specified in Part IV of the alert service bulletin. \n\n\tIn addition to the repetitive inspections, the alert service bulletin describes procedures for an additional one-time inspection as follows: If any findings from inspections done in accordance with the original issue or Revision 1 of the service bulletin led to a rejection of any fasteners, or if there were any equivalent findings prior to the original issue of the service bulletin (except for findings on airplanes identified as Group 1, Configuration 2 in Revision 3 of the alert service bulletin that are prior to the incorporation of Boeing Service Bulletin 757-54-0035), the alert service bulletin describes a high frequency eddy current (HFEC) inspection for cracking of the four critical fastener holes in the horizontal flange and repair if necessary. \n\n\tDepending on the group and configuration specified in the alert service bulletin, the initial compliance time ranges from 90 days after the date on the service bulletin to 6,000 flight cycles or 36 months, whichever occurs first, after the incorporation of Boeing Service Bulletin 757-54-0035. Depending on the group and configuration specified in the alert service bulletin, the repetitive interval ranges from 6,000 flight cycles or 36 months, whichever occurs first, to 9,000 flight cycles or 54 months, whichever occurs first. \n\nFAA's Determination and Requirements of This AD \n\n\tThe unsafe condition described previously is likely to exist or develop on other airplanes of the same type design. For this reason, we are issuing this AD to supersede AD 2005-12-04. This new AD continues to require repetitive inspections of the shim installation between the vertical flange and bulkhead, and repair if necessary. This AD also requires, for certain airplanes, an inspection for cracking of the four critical fastener holes in the horizontal flange, and repair if necessary. \n\nDifferences Between This AD and the Alert Service Bulletin \n\n\tThe alert service bulletin specifies to contact the manufacturer for instructions on how to repair certain conditions, but this AD requires repairing those conditions in one of the following ways: \n\n\tUsing a method that we approve; or \n\n\tUsing data that meet the certification basis of the airplane, and that have been approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization whom we have authorized to make those findings. \n\nFAA's Determination of the Effective Date \n\n\tAn unsafe condition exists that requires the immediate adoption of this AD; therefore, providing notice and opportunity for public comment before the AD is issued is impracticable, and good cause exists to make this AD effective in less than 30 days. \n\nComments Invited \n\n\tThis AD is a final rule that involves requirements that affect flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any relevant written data, views, or arguments regarding this AD. Send your comments to an address listed in the ADDRESSES section. Include "Docket No. FAA-2007-28920; Directorate Identifier 2007-NM-162-AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD that might suggest a need to modify it. \n\n\tWe will post all comments we receive, without change, to http://dms.dot.gov , including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov. \n\nExamining the Docket \n\n\tYou may examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Operations office (telephone (800) 647-5527) is located on the ground level of the West Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them. \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 the regulation: \n\n\t1. Is not a "significant regulatory action'' under Executive Order 12866; \n\n\t2. Is not a "significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and \n\n\t3. 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\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 part 39 of the Federal Aviation Regulations (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 removing amendment 39-14120 (70 FR 34313, June 14, 2005) and adding the following new airworthiness directive (AD):