The FAA issued AD 76-18-01 (41 FR 37093, September 2, 1976) on August 23, 1976, which amended AD No. 73-3-1 (38 FR 2331). AD 76-18-01 required visually inspecting the aluminum end fittings of each strut for deformation or damage and dye-penetrant inspecting for a crack and, if deformation, damage or a crack is found, modifying or replacing the part. Modifying or replacing the parts within specified hours time-in-service (TIS) is also required. Also, that AD requires inspecting the tailboom center attach fittings and center frame aft cluster fittings for damage, and if damaged parts are found, replacing the damaged parts. \n\n\tSince the issuance of that AD, an accident occurred in the United Kingdom involving an in-flight structural failure of a Schweizer Model 269C helicopter. The Air Accidents Investigation Branch of the United Kingdom investigated the accident and recommended that the FAA issue an AD requiring certain inspections of the clevis lugs and replacing certain cluster fittings. The FAA determined that the unsafe condition was due to cracking of the cluster fitting. Therefore, on December 14, 2001, the FAA issued AD 2001-25-52 to supersede AD 76-18-01. AD 2001-25-52 retains the inspection, modification and replacement requirements of the strut, but adds a requirement to dye-penetrant inspect the lugs on both cluster fittings within 10 hours TIS and at specified intervals, and, before further flight, replace any cracked cluster fitting. \n\n\tThe FAA has reviewed Schweizer Service Information Notice No. N-109.2, dated, September 1, 1976, which describes procedures for inspecting tailboom support strut aluminum end fittings and replacing aluminum end fittings with stainless steel end fittings. The FAA has also reviewed Schweizer Service Information Notice No. N-108, dated May 21, 1973, which describes procedures for serializing the tailboom support strut assembly. \n\n\tSince the unsafe condition described is likely to exist or develop on other Schweizer Model 269A, 269A-1, 269B, 269C, and TH-55A helicopters of the same type designs, the FAA issued Emergency AD 2001-25-52 to prevent failure of a lug on a cluster fitting, rotation of a tailboom into the main rotor blades, and subsequent loss of control of the helicopter. The AD requires the following: \n\nInitially and at specified intervals, inspect the lugs on both cluster fittings, certain strut assemblies, certain tail boom attachments and center frame aft cluster fittings. If damage or a crack is found, before further flight replace each damaged or cracked part with an airworthy part; \n\nModify or replace each strut assembly within the specified TIS or one year, whichever occurs first; and \n\nSerialize certain strut assemblies. \n\n\tThe actions must be accomplished in accordance with the service information notices described previously. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the structural integrity of the helicopter. Therefore, the actions previously stated are required at the specified time intervals, and this AD must be issued immediately. \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 letters issued on December 14, 2001 to all known U.S. owners and operators of Schweizer Model 269A, 269A-1, 269B, 269C, and TH-55A helicopters. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to 14 CFR 39.13 to make it effective to all persons. \n\n\tThe FAA estimates that 500 helicopters of U.S. registry will be affected by this AD. It will take approximately 2.5 work hours for each dye-penetrant inspection, 12 work hours to replace one cluster fitting, 4 work hours to modify or replace the strut assembly, and 0.25 work hours to serialize the strut assembly. The average labor rate is $60 per work hour. Required parts will cost approximately $5.00 for each fitting inspection, $1635 to replace a cluster fitting, and $1500 to modify or replace the strut assembly. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $283,280 (assuming 1000 cluster fittings are inspected, 50 cluster fittings are replaced, 6 strut assemblies are modified or replaced, and 6 strut assemblies are serialized). \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 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\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 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 mailed 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. 2001-SW-58-AD." The postcard will be date stamped and returned to the commenter. \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\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\n\t1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\nSec. 39.13 (Amended) \n\n\t2. Section 39.13 is amended by adding a new airworthiness directive to read as follows: