On July 3, 2000, the FAA issued emergency AD 2000-13-51, which is applicable to all Boeing Model 737-200 and -300 series airplanes equipped with a main deck cargo door installed in accordance with Supplemental Type Certificate (STC) SA2969SO.\n\n\tThat 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 exact cause of the cracking is unknown at this time. The area of the cracking is between frame station (FS) 361.87 and FS 498.12 where the latch fittings attach to the main deck cargo door frames. Such cracking in the lower portion of the main deck cargo door frames could cause reduced structural integrity of the main deck cargo door. This condition, if not corrected, could result in sudden depressurization, loss or opening of the main deck cargo door during flight, and loss of control of the airplane.Explanation 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 2000-13-51 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 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 FS 361.87 and FS 498.12, and between 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. \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 notices issued on July 3, 2000 to all known U.S. owners and operators of Boeing Model 737-200 and -300 series airplanes equipped with a main deck cargo door installed in accordance with STC SA2969SO. 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\nReporting Requirements\n\n\tThis AD also requires that operators report the results of the special detailed inspection to the FAA. Because the cause of the addressed cracking is not currently known, the intent of these required inspection reports is to enable the FAA to determine how widespread such cracking problems may be in the affected fleet. \n\nInterim Action\n\n\tThis is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking.\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\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-216-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, Safety.\n\nAdoption of the Amendment\n\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: \n\nPART 39 - AIRWORTHINESS DIRECTIVES\n\t1. The authority citation for part 39 continues to read as follows: \nAuthority: 49 U.S.C. 106(g), 40113, 44701. \n§ 39.13 (Amended)\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: