The FAA has received reports of cracking in the fuselage skin and bear strap at the forward, upper corner of the L1 entry door cutout on Boeing Model 757-200 series airplanes. A 6.0-inch crack was found on an airplane having 27,071 total flight cycles. A 1.4-inch crack was also found on an airplane having 29,340 total flight cycles, and a 1.7-inch crack was found in the bear strap on an airplane having 26,686 total flight cycles. These cracks were found during visual inspections during maintenance and were attributed to fatigue caused by pressurization cycles. \n\n\tThis condition, if not corrected, could result in reduced structural integrity of the L1 entry door and consequent rapid decompression of the airplane. \n\nExplanation of Relevant Service Information \n\n\tThe FAA has reviewed and approved Boeing Special Attention Service Bulletin 757-53-0089, dated March 18, 2004. The service bulletin describes procedures for performing initial and repetitive highfrequency eddy current (HFEC) and low frequency eddy current (LFEC) inspections for cracking of the fuselage skin around the adjacent fasteners, along the edge of the skin and bear strap, and the bear strap around the fasteners adjacent at the forward, upper corner of the L1 entry door cutout; as applicable. The service bulletin specifies to contact Boeing for repair instructions for any cracks found during the HFEC and LFEC inspections. \n\n\tThe service bulletin also describes procedures for accomplishing a preventative modification, which eliminates the need for the repetitive inspections. The modification includes performing a general visual inspection to ensure that the fastener edge margins adjacent to the forward, upper corner of the L1 entry door cutout are 0.5 inch or greater; and related investigative/corrective actions, if necessary. Related investigative actions include repeating the general visual inspection at specified intervals if the margins are less than 0.50 inch or removing the fasteners and performing an HFEC inspection on the holes in the fuselage skin and bear strap if the margins are equal to or greater than 0.50 inch. The corrective actions include coldworking the fastener holes and installing over-sized fasteners if no crack is found during the HFEC inspection or contacting Boeing for repair instructions if any crack is found during either the general visual or the HFEC inspection. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition. \n\nExplanation of the Requirements of the Rule \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, this AD requires accomplishment of the actions specified in the service bulletin described previously, except as discussed below. This AD also provides for optional terminating action for the repetitive inspections. \n\nDifferences Between This AD and the Service Bulletin \n\n\tAlthough the service bulletin specifies that operators contact the manufacturer for disposition of certain repair conditions, this AD requires operators to repair those conditions per a method approved by the FAA, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the FAA to make such findings. \n\nDetermination of Rule's Effective Date \n\n\tSince a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. \n\nComments Invited \n\n\tAlthough this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule.Interested persons are invited to comment on this rule by submitting such written data, views, or arguments, as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption ADDRESSES. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed. \n\n\tSubmit comments using the following format: \n\nOrganize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues. \n\nFor each issue, state what specific change to the AD is being requested\n\nInclude justification (e.g., reasons or data) for each request. \n\n\tComments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket. \n\n\tCommenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 2004-NM-44-AD." The postcard will be date stamped and returned to the commenter. \n\nRegulatory Impact \n\n\tThe regulations adopted herein 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. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. \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 it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption ADDRESSES. \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, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration 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\n§ 39.13 (Amended) \n\n2. Section 39.13 is amended by adding the following new airworthiness directive: