Background \n\n\n\tThe FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain Leonardo S.p.a. Model AW189 helicopters. The NPRM published in the Federal Register on June 10, 2021 (86 FR 30822). In the NPRM, the FAA proposed to require determining the total hours time-in-service (TIS) and total number of landings of tail gearbox fitting part number (P/N) 4F5350A04152. If the total hours TIS and total number of landings cannot be determined, the NPRM would require removing the part from service. Also, the NPRM would establish a life limit for tail gearbox fitting P/N 4F5350A04152 and require removing the part from service according to the new life limit. The NPRM was prompted by EASA AD 2018-0087, dated April 18, 2018 (EASA AD 2018-0087), issued by EASA, which is the Technical Agent for the Member States of the European Union, to correct an unsafe condition for Leonardo S.p.A. Helicopters (formerly Finmeccanica S.p.A., AgustaWestland S.p.A.) Model AW189 helicopters. EASA advises of revisions resulting in Leonardo AW189 Maintenance Manual, Document 89- A-AMPI-00-P, Chapter IV, Airworthiness Limitations, Issue 13 (89-A- AMPI-00-P ALS Issue 13), which includes new and/or more restrictive airworthiness limitations and maintenance tasks since its original issuance. Failure to accomplish those airworthiness limitations and maintenance tasks could result in an unsafe condition. This condition, if not addressed, could result in failure of a part, which could result in loss of control of the helicopter. \n\tAccordingly, EASA AD 2018-0087 requires accomplishing the actions specified in 89-A-AMPI-00-P ALS Issue 13 and revising the Aircraft Maintenance Program (AMP) with the actions specified in 89-A-AMPI-00-P ALS Issue 13. \n\nDiscussion of Final Airworthiness Directive \n\nComments \n\n\n\tThe FAA received no comments on the NPRM or on the determination of the costs. \n\nConclusionThese helicopters have been approved by EASA and are approved for operation in the United States. Pursuant to the FAA's bilateral agreement with the European Union, EASA has notified the FAA about the unsafe condition described in its AD. The FAA reviewed the relevant data and determined that air safety requires adopting this AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on these helicopters. This AD is adopted as proposed in the NPRM. \n\nRelated Service Information \n\n\n\tThe FAA reviewed AW189 Air Vehicle Maintenance Planning Information, 89-B-AMPI-00-P, Chapter 4, Issue 6, dated July 17, 2018 (89-B-AMPI-00-P ALS Issue 6). 89-B-AMPI-00-P ALS Issue 6 specifies various airworthiness limitations information including retirement lives, mandatory inspections, and certification maintenance requirements. 89-B-AMPI-00-P ALS Issue 6 is equivalent to 89-A-AMPI-00- P ALS Issue 13. \n\nDifferences Between This AD and the EASA AD \n\n\n\tEASA AD 2018-0087 applies to Model AW189 helicopters, whereas this AD applies to that model helicopter with tail gearbox fitting P/N 4F5350A04152 installed instead. EASA AD 2018-0087 requires accomplishing the actions specified in 89-A-AMPI-00-P ALS Issue 13 and revising the AMP with the actions specified in 89-A-AMPI-00-P ALS Issue 13, whereas this AD requires establishing a life limit for tail gearbox fitting P/N \n\n((Page 46762)) \n\n4F5350A04152 and removing that part from service accordingly instead. \n\nCosts of Compliance \n\n\n\tThe FAA estimates that this AD affects 4 helicopters of U.S. Registry. Labor rates are estimated at $85 per work-hour. Based on these numbers, the FAA estimates the following costs to comply with this AD. \n\tReplacing a tail gearbox fitting takes about 48 work-hours and parts cost about $30,000 for an estimated cost of $34,080 per helicopter and $136,320 for the U.S. fleet, per replacement cycle. \n\nAuthority for This Rulemaking \n\n\n\tTitle 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority. \n\tThe FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on helicopters identified in this rulemaking action. \n\nRegulatory Findings \n\n\n\tThis AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between thenational government and the States, or on the distribution of power and responsibilities among the various levels of government. \n\tFor the reasons discussed above, I certify that this AD: \n\t(1) Is not a ''significant regulatory action'' under Executive Order 12866, \n\t(2) Will not affect intrastate aviation in Alaska, and \n\t(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. \n\nList of Subjects in 14 CFR Part 39 \n\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.