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 Leonardo S.p.a. Model AB139 and AW139 helicopters with an EFS control panel part number (P/N) 3G9560V00556 (for use with night vision goggle) or 3G9560V00557 (standard) installed. The NPRM published in the Federal Register on May 25, 2021 (86 FR 28040). In the NPRM, the FAA proposed to require replacing EFS control panel P/Ns 3G9560V00556 and 3G9560V00557 with EFS control panel P/Ns 3G9560V00559 and 3G9560V00558, respectively. The NPRM also proposed to prohibit installing EFS control panel P/Ns 3G9560V00556 and 3G9560V00557 on any helicopter. The NPRM was prompted by EASA AD 2015-0172, dated August 21, 2015 (EASA AD 2015-0172), issued by EASA, which is the Technical Agent for the Member States of the European Union, to correct an unsafe condition for AgustaWestland S.p.A (formerly Agusta S.p.A.), AgustaWestland Philadelphia Corporation (formerly Agusta Aerospace Corporation) (now Leonardo S.p.a.) Model AB139 and AW139 helicopters with an EFS installed. EASA advises of two events of uncommanded EFS deployment during flight. Subsequent investigation revealed that these conditions had been caused by improper design of EFS control panel P/Ns 3G9560V00556 (for use with night vision goggle) and 3G9560V00557 (standard). This condition, if not addressed, could result in reduced control of the helicopter. \n\tAccordingly, EASA AD 2015-0172 requires replacing EFS control panel P/Ns 3G9560V00556 and 3G9560V00557 with EFS control panel P/Ns 3G9560V00559 and 3G9560V00558, respectively. EASA AD 2015-0172 also prohibits installing EFS control panel P/Ns 3G9560V00556 and 3G9560V00557 on any helicopter. \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\nConclusion \n\n\n\tThese 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. \n\nRelated Service Information \n\n\n\tThe FAA reviewed AgustaWestland Bollettino Tecnico No. 139-374, dated July 6, 2015. This service information specifies procedures for replacing EFS control panel P/Ns 3G9560V00556 and 3G9560V00557 with EFS control panel P/Ns 3G9560V00559 and 3G9560V00558, respectively. This service information also notes that EFS control panel P/Ns 3G9560V00556 and 3G9560V00557 can be upgraded by following Sirio Panel Service Bulletins 6WS-MI100135 Ed.01 and 6WS-MI100134 Ed.01. \n\nDifferences Between This AD and the EASA AD \n\n\n\tEASA AD 2015-0172 applies to Model AB139 and AW139 helicopters with an EFS installed, whereas this AD applies to those model helicopters with EFS control panel P/N 3G9560V00556 (for use with night vision goggle) or 3G9560V00557 (standard) installed instead. EASA AD 2015-0172 specifies replacing an affected EFS control panel within a compliance time of flight hours or months, whichever occurs first, based on helicopter configuration, whereas this AD requires that replacement within a shorter compliance time in hours time-in-service but the same number of months, based on helicopter configuration instead. \n\nCosts of Compliance \n\n\n\tThe FAA estimates that this AD affects 133 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 an EFS control panel takes about 1 work-hour and parts cost about $12,342 for an estimated cost of $12,427 per helicopter and up to $1,652,791 for the U.S. fleet. \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 the national 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.