A proposal to amend part 39 of the Federal Aviation Regulations to include an airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model MD-11 series airplanes was published in the Federal Register on August 19, 1993 (58 FR 44150). That action proposed to require modification or replacement of designated passenger cabin floor panels.\n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.\n\n\tTwo commenters support the proposed rule.\n\n\tThe Air Transport Association (ATA) of America, on behalf of several of its members, requests that the FAA withdraw the proposed rule. The commenter states that all U.S. operators and all but one non-U.S. operator have accomplished the modification or replacement specified in McDonnell Douglas MD-11 Service Bulletin 53-31, which is cited in the proposed rule, thereby ensuring that 9g crash certification requirements are satisfied. The commenter adds that McDonnell Douglas MD-11 Service Bulletins 53-32 and 53-33, which are also cited in the proposal, were only included in the manufacturer's service program to ensure commonality between operators, but were not included in that program to return the aircraft to its original design intent. The commenter concludes that, since all U.S. operators have accomplished the actions described in McDonnell Douglas MD-11 Service Bulletin 53-31, there is no need for an AD. Further, the commenter believes that issuance of the AD would contradict the principles of Presidential Executive Order 12866 (Regulatory Planning and Review), and would cause an unjustifiable expense to operators.\n\n\tThe FAA does not concur with the commenter's request to withdraw the proposed rule. As explained in the preamble to the proposal, the FAA has determined that accomplishment of the modification or replacement described in McDonnell Douglas MD-11 ServiceBulletin 53-31 is necessary to correct an unsafe condition described as loss of the passenger cabin floor capability to support the airplane interior inertia loads under emergency landing conditions. Under existing bilateral airworthiness agreements, the FAA is obligated, through the AD process, to advise foreign airworthiness authorities of unsafe conditions relating to products produced in the United States, and to provide instructions determined necessary to correct the unsafe condition addressed. The appropriate vehicle for mandating such action to correct an unsafe condition is the airworthiness directive.\n\n\tHowever, upon consideration of data submitted by the manufacturer since issuance of the proposal, the FAA has determined that accomplishment of the modification or replacement specified in McDonnell Douglas MD-11 Service Bulletin 53-31 adequately addresses the unsafe condition, and that the actions described in McDonnell Douglas MD-11 Service Bulletins 53-32 and 53-33 arenot necessary to address that unsafe condition. The FAA's original concern was that interchanging the floor panels could result in an unsafe condition under emergency landing conditions. However, based on the data received from the manufacturer, the FAA finds that its concern regarding floor panel interchangeability is addressed by part number controls; original panels are not interchangeable with reworked panels or new panels. In light of this, the FAA has removed paragraphs (b) and (c) from the final rule. In addition, references to McDonnell Douglas MD-11 Service Bulletins 53-32 and 53-33 have been removed from the applicability of the AD. The FAA also has revised the economic impact paragraph, below, to reflect the fact that all U.S. airplanes have accomplished the requirements of this AD.\n\n\tOne commenter requests that paragraph (a) of the proposed rule be revised to clarify that each individual panel may be reworked in accordance with Option I of McDonnell Douglas MD-11 Service Bulletin 53-31, or replaced in accordance with Option II of that service bulletin, rather than implying that all panels must be either reworked or replaced. The commenter also requests that the proposal be revised to indicate that installation of operator-manufactured panels with properly installed inserts are acceptable in lieu of production panels.\n\n\tThe FAA concurs. Paragraph (a) of this AD has been revised to indicate that the requirements of that paragraph may be accomplished by either reworking an individual panel in accordance with Option I of the service bulletin, or replacing an individual panel in accordance with Option II of the service bulletin. Paragraph (a) of the final rule also has been revised to specify that new panels that meet the original type design or FAA-approved equivalent panels are considered acceptable replacement panels.\n\n\tAfter careful review of the available data, including the comments noted above, the FAA has determined that air safety andthe public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.\n\n\tThere are approximately 32 Model MD-11 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 20 airplanes of U.S. registry will be affected by this AD. The FAA has been advised that the requirements of this AD have been accomplished on all 20 airplanes of U.S. registry.\n\n\tHowever, should an affected airplane be imported and placed on the U.S. Register in the future, the FAA has been advised that the manufacturer plans to provide required parts and to accomplish the required modification at no expense to operators. Therefore, there is no future economic cost impact of this rule on U.S. operators.\n\n\tThe regulations adopted herein will not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.\n\n\tFor the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) 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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it 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\n\tAccordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 14 CFR part 39 of the Federal Aviation Regulations as follows:\n\nPART 39 - AIRWORTHINESS DIRECTIVES\n\n\t1.\tThe authority citation for part 39 continues to read as follows:\n\nAuthority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.\n\n§ 39.13 - (Amended)\n\n\t2.\tSection 39.13 is amended by adding the following new airworthiness directive: