On February 17, 2005, we issued emergency AD 2005-04-51, which applies to certain Boeing Model 747-100B SUD, -200B, -200C, -200F, and -300 series airplanes. \n\nBackground \n\n\tOn May 7, 1991, we issued AD 91-11-01, amendment 39-6997 (56 FR 22306, May 15, 1991), for certain Boeing Model 747 series airplanes. That AD requires repetitive inspections for cracks of the frame structure and skin in the fuselage section 41, and repair if necessary. That AD also provides for an optional terminating action for the repetitive inspections. That AD was prompted by recommendations of the FAA-sponsored Boeing Model 747 Structures Working Group. We issued that AD to prevent sudden decompression of the fuselage. \n\n\tSince the issuance of AD 91-11-01, we have received several reports of large fatigue cracks common to fuselage frames in the upper deck area on Boeing Model 747-200C, -200F, and -300 series airplanes. Most of these airplanes had been inspected in accordance withAD 91-11-01. Many fatigue cracks occurred near stringers S-10 and S-10A, but other cracks were also reported. The cracking is due to cyclic pressurization of the airplanes. \n\n\tWe also have received two recent reports of severed or nearly severed adjacent frames at body station (BS) 420 and BS 440 near stringer S-10A on Boeing Model 747-300 series airplanes. Both airplanes had been inspected in accordance with AD 91-11-01. In both reports, missing fasteners common to the skin at frame shear tie flanges were detected in the vicinity of cracks. In one case, eight fasteners were missing from the body skin at the severed frame at BS 440. One airplane had accumulated 11,641 total flight cycles; the other airplane had accumulated 11,880 total flight cycles. \n\n\tIn light of these reports, we have determined that, for certain Boeing Model 747-100B SUD, -200C, -200F, and -300 series airplanes; and certain Boeing Model 747-200B series airplanes retrofitted with a stretched upper deck (SUD); the inspections required by AD 91-11-01 do not adequately detect fatigue cracks at BS 420, 440, and 460 between stringers S-8 and S-12 inclusive. Such fatigue cracking, if not detected and corrected in a timely manner, could lead to severed frames, and consequent rapid decompression and loss of the structural integrity of the airplane. \n\nOther Relevant Rulemaking \n\n\tOn January 16, 1990, we issued AD 90-06-06, amendment 39-6490 (55 FR 8374, March 7, 1990), for certain Boeing Model 747 series airplanes. That AD requires incorporation of certain structural modifications. We issued that AD to prevent degradation in the structural capabilities of the affected airplanes. One of the required modifications incorporates a modification (reference Boeing Service Bulletin 747-53-2272, Revision 12, dated December 22, 1988) that ends the repetitive inspections of the frames in Zone 2 required by this AD. \n\nRelevant Service Information \n\n\tWe have reviewed Boeing Alert Service Bulletin 747-53A2265, Revision 9, dated February 17, 2005. Among other actions, the service bulletin describes procedures for repetitive surface high frequency eddy current (HFEC) inspections for cracks in the frames at BS 420, 440, and 460 between stringers S-8 and S-12 inclusive on the left and right sides of the airplane. \n\nFAA's Determination and Requirements of This AD \n\n\tWe evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other Boeing Model 747- 100B SUD, -200C, -200F, and -300 series airplanes; and Boeing Model 747-200B series airplanes retrofitted with a SUD of this same type design. Therefore, we issued emergency AD 2005-04-51 to detect and correct fatigue cracks in the frames and body skin at BS 420, 440, and 460 between stringers S-8 and S-12 inclusive, which could lead to severed frames, and consequent rapid decompression and loss of the structural integrity of the airplane. The AD requires repetitive external detailed inspections for cracked skin or loose or missing fasteners of the body skin between BS 420 and 460 inclusive and between stringers S-8 and S-12 inclusive on the left and right sides of the airplane. If any cracked skin or loose or missing fastener is detected, the AD also requires a surface HFEC inspection for cracks in the frames at BS 420, 440, and 460 between stringers S-8 and S-12 on the left and right sides of the airplane; repair of any cracked frame or skin; and replacement of any loose of missing fastener with a new fastener; as applicable. Accomplishing the HFEC inspection ends the repetitive external detailed inspections. The HFEC inspections must be done in accordance with the service information described previously. \n\n\tWe found that immediate corrective action was required; therefore, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual notices issued on February 17, 2005, to all known U.S. owners and operators of certain Boeing Model 747-100B SUD, -200B, -200C, -200F, and -300 series airplanes. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons. \n\nInterim Action \n\n\tWe consider this AD interim action. We are currently considering superseding this emergency AD and AD 91-11-01 to, among other actions, reduce the initial threshold of the inspections required by AD 91-11-01 for certain airplanes and to add other actions specified in Boeing Alert Service Bulletin 747-53A2265, Revision 9, dated February 17, 2005. \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 under ADDRESSES. Include "Docket No. FAA-2005-20431; Directorate Identifier 2005-NM-040-AD" at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD. We will consider all comments received by the closing date and may amend the AD in light of those comments. \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 our docket 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 can review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov. \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\tThe FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If this emergency regulation is later deemed significant under DOT Regulatory Policies and Procedures, we will prepare a final regulatory evaluation and place it in the AD Docket. See the ADDRESSES section for a location to examine the regulatory evaluation, if filed. \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 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 FAA amends Sec. 39.13 by adding the following new airworthiness directive (AD):