On July 13, 2000, the FAA issued AD 2000-13-51, amendment 39-11826 (65 FR 44977, July 20, 2000), applicable to certain Boeing Model 737-200 and -300 series airplanes. \n\nThat AD requires repetitive special detailed inspections to detect cracking of the main deck cargo door frames, their existing reinforcing angles (where applicable), and the attach holes of the latch fittings between frame station (FS) 361.87 and FS 498.12, and between water line (WL) 202.35 and WL 213.00, in the area where the main deck cargo door latch fittings attach to the frames; and corrective actions, if necessary. That action was prompted by a report indicating that three of the subject airplanes had multiple cracks in the lower portion of the main deck cargo door frames and, in some cases, the reinforcing angles. The actions required by that AD are intended to detect and correct cracking of the lower portion of the main deck cargo door frames, which could result in sudden depressurization, loss or opening of the main deck cargo door during flight, and loss of control of the airplane. \n\nActions Since Issuance of Previous Rule \n\n\tSince the issuance of AD 2000-13-51, the FAA has received reports that, during the special detailed inspections (i.e., borescope) required by that AD, cracks were found in the reinforcing angles of the main deck cargo door frame. Subsequent disassembly of the affected structure revealed substantial cracking that was hidden by the layered structure and not detected by the special detailed inspections. These findings are a clear indication of multiple element damage (MED). MED is a source of widespread fatigue damage (WFD), which is characterized by the simultaneous presence of cracks in multiple structural details that are of sufficient size and density, whereby the structure will no longer meet its damage tolerance requirements. Therefore, the FAA has determined that a high frequency eddy current (HFEC) inspection of all affected structural elements of the main deck cargo door, and replacement of any cracked part with a new part having the same part number are necessary to prevent reduced structural integrity of the main deck cargo door, which could result in sudden depressurization, loss or opening of the main deck cargo door during flight, and loss of control of the airplane. \n\nExplanation of Relevant Service Information \n\n\tThe FAA has reviewed and approved Pemco Service Bulletin 737-52-0037, including Attachment 1, dated August 10, 2000. The service bulletin describes procedures for an HFEC inspection to detect cracks of the lower frames and reinforcing angles of the main deck cargo door where the door latch fittings attach between FS 361.87 and FS 498.12 and WL 202.35 and WL 213.00, and replacement of any cracked part with a new part having the same part number.\n \nExplanation of Requirements of the Rule \n\n\tSince the unsafe condition described is likely to exist or develop on other airplanes of the same type design, the FAA issued emergency AD 2000-17-51 to detect and correct cracking of the lower portion of the main deck cargo door frames, which could result in sudden depressurization, loss or opening of the main deck cargo door during flight, and loss of control of the airplane. The AD supersedes AD 2000-13-51 to require a one-time HFEC inspection to detect cracks of the lower frames and reinforcing angles of the main deck cargo door where the door latch fittings attach between FS 361.87 and FS 498.12 and WL 202.35 and WL 213.00, and replacement of any cracked part with a new part having the same part number. The actions are required to be accomplished in accordance with the service bulletin previously described. \n\n\tSince it was found that immediate corrective action was required, 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 noticesissued on August 14, 2000, to all known U.S. owners and operators of certain Boeing Model 737-200 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\tThe FAA is considering further rulemaking action to supersede this AD to require replacement of the main deck cargo door frames and reinforcing angles that have accumulated 7,000 or more total flight cycles with new parts. However, the planned compliance time for these actions is sufficiently long so that prior notice and time for public comment will be practicable. \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 tocomment 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\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 2000-NM-277-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 beendetermined 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\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \nAdoption of the Amendment \n\tAccordingly, 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: PART 39 - AIRWORTHINESS DIRECTIVES \n\t1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 (Amended) \n\t2.Section 39.13 is amended by removing amendment 39-11826 (65 FR 44977, July 20, 2000), and by adding a new airworthiness directive (AD), amendment 39-11877, to read as follows: