On March 4, 1998, the FAA issued priority letter AD 98-06-04, applicable to Eurocopter France Model AS332C, L, and L1 and Model SA330F, G, and J helicopters, which requires performing a procedure to determine the play of the tail rotor gearbox within 25 hours time-in-service (TIS), and repeating the procedure at intervals of 100 hours TIS or 520 hours TIS depending on the amount of play that is detected. That action was prompted by an accident involving a Model SA330 helicopter that occurred on October 21, 1997, which resulted from the loss of the tail rotor drive. An investigation determined that the loss of tail rotor drive was caused by excessive play between the tail rotor gearbox bevel gear and the bevel wheel. This condition, if not corrected, could result in failure of the tail rotor gearbox, loss of tail rotor drive and subsequent loss of control of the helicopter. \n\n Since the unsafe condition described is likely to exist or develop on other Eurocopter France Model AS332C, L, and L1 and Model SA330F, G, and J helicopters of the same type design, the FAA issued priority letter AD 98-06-04 to prevent failure of the tail rotor gearbox, loss of tail rotor drive and subsequent loss of control of the helicopter. The AD requires, within 25 hours TIS after the effective date of this AD, and thereafter at specified intervals, performing a procedure to determine the angular play of the tail rotor gearbox and replacing the tail rotor gearbox with an airworthy gearbox if the specified angular play limit is exceeded. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the controllability of the helicopter. Therefore, inspections of the tail rotor gearbox for excessive play is required within 25 hours TIS or upon or before attaining 520 hours TIS and this AD must be issued immediately.\n\n Since 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 letters issued on March 4, 1998 to all known U.S. owners and operators of Eurocopter France Model AS332C, L, and L1 and Model SA330F, G, and J helicopters. 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. However, the FAA has made several nonsubstantive editorial changes since the issuance of Priority Letter AD 98-06-04; the word "excess" was changed to "excessive," the incorrect placement of the number "12" in Figure 1 has been corrected, and a new paragraph was added to clarify that brackets and mounts installed during the required inspection are to be removed between inspections. The FAA has determined that these changes will neither increasethe economic burden on an operator nor increase the scope of the AD.\n \n The FAA estimates that 4 helicopters of U.S. registry will be affected by this AD, that it will take approximately 3 work hours per helicopter to accomplish the required actions, and that the average labor rate is $60 per work hour. Required parts will cost approximately $100 per helicopter to create the necessary tools and $45,000 to replace the gearbox, if necessary. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $45,280 per helicopter.\n\nComments Invited\n Although 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 should 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 Comments 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 Commenters 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 No. 98-SW-11-AD." The postcard will be date stamped and returned to the commenter.\n \n The 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 The 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 DOTRegulatory 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 Air transportation, Aircraft, Aviation safety, Safety.\n\nAdoption of the Amendment\n Accordingly, 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 1. The authority citation for part 39 continues to read as follows: \n Authority: 49 U.S.C. 106(g), 40113, 44701.\n\n§ 39.13 (Amended)\n 2. Section 39.13 is amended by adding a new airworthiness directiveto read as follows: