Discussion \n\n\n\tThe FAA has received reports of four instances of IFSDs occurring on the affected model turbofan engines since 2019. \n\tIn response to the two IFSDs that occurred in July and September 2019, and in response to on-going investigations of these IFSDs, the FAA issued AD 2019-19-11 (84 FR 50719, September 26, 2019), to perform inspections of the LPC R1 to prevent failures. The FAA subsequently superseded AD 2019-19-11, issuing AD 2019-21-11 (84 FR 57813, October 29, 2019) in response to another IFSD and to expand the population of affected engines that needed inspection of the LPC R1. Since the effective date of AD 2019-21-11, another IFSD occurred in February 2020. Analysis by the manufacturer determined that the LPC vane schedules were putting the engine in a condition to experience an acoustic resonance that damages the LPC R1, which then leads to LPC R1 failure. In response, the manufacturer updated the EEC FADEC software to improve vanescheduling to avoid acoustic resonance. \n\tThis condition, if not addressed, could result in uncontained release of the LPC R1, damage to the engine, and damage to the airplane. The FAA is issuing this AD to address the unsafe condition on these products. \n\nRelated Service Information \n\n\n\tThe FAA reviewed PW Service Bulletin (SB) PW1000G-A-73-00-0036-00A- 930A-D, Issue No. 002, dated March 4, 2020, and PW SB PW1000G-A-73-00- 0041-00A-930A-D, Issue No.001, dated March 4, 2020. These SBs describe procedures for replacing or modifying the EEC FADEC software. \n\nFAA's Determination \n\n\n\tThe FAA is issuing this AD because it evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. \n\nAD Requirements \n\n\n\tThis AD requires the removal from service of certain EEC FADEC software and the installation of a software version eligible for installation. \n\nInterim ActionThe FAA considers this AD interim action. The root cause of the LPC R1 failures is still being investigated and the FAA will consider further rulemaking depending on the results of the investigation. \n\nJustification for Immediate Adoption and Determination of the Effective Date \n\n\n\tSection 553(b)(3)(B) of the Administrative Procedure Act (APA) (5 U.S.C.) authorizes agencies to dispense with notice and comment procedures for rules when the agency, for ''good cause,'' finds that those procedures are ''impracticable, unnecessary, or contrary \n\n((Page 17743)) \n\nto the public interest.'' Under this section, an agency, upon finding good cause, may issue a final rule without seeking comment prior to the rulemaking. Similarly, Section 553(d) of the APA authorizes agencies to make rules effective in less than 30 days, upon a finding of good cause. \n\tAn unsafe condition exists that requires the immediate adoption of this AD without providing an opportunity for public comments prior toadoption. The FAA has found that the risk to the flying public justifies waiving notice and comment prior to adoption of this rule. In addition to three failures of the LPC R1 installed on PW1500G model turbofan engines occurring in 2019, an additional failure of the LPC R1 occurred on February 12, 2020. LPC rotor failures can release high- energy debris from the engine and damage the airplane (see AC 39-8, ''Continued Airworthiness Assessments of Powerplant and Auxiliary Power Unit Installations of Transport Category Airplanes,'' dated September 8, 2003). \n\tThe failures of the LPC R1 occurred on engines that were shipped to operators as spare engines and were not delivered installed on aircraft. The failures occurred within 300 flight cycles (FCs) since installation of the engine onto an aircraft. The manufacturer has recommended that the new engine software be loaded into the engine as soon as the engines are installed on an aircraft or within 15 FCs after installation if the engine was installed onto an aircraft recently. These engines are the highest risk for LPC R1 failures. The remainder of the fleet is also at risk for LPC R1 failures and needs to have the software upgraded within 90 days to prevent additional LPC R1 failures and maintain an acceptable level of safety. \n\tThe FAA considers these LPC R1 failures to be an urgent safety issue, requiring immediate action involving replacement of the EEC FADEC software. Accordingly, notice and opportunity for prior public comment are impracticable and contrary to public interest pursuant to 5 U.S.C. 553(b)(3)(B). In addition, for the reasons stated above, the FAA finds that good cause exists pursuant to 5 U.S.C. 553(d) for making this amendment effective in less than 30 days. \n\nComments Invited \n\n\n\tThis AD is a final rule that involves requirements affecting flight safety and was not preceded by notice and an opportunity for public comment. However, the FAA invites you to send any written data, views, or arguments about this final rule. Send your comments to an address listed under the ADDRESSES section. Include the docket number FAA-2020- 0299 and Project Identifier AD-2020-00247-E at the beginning of your comments. The FAA specifically invites comments on the overall regulatory, economic, environmental, and energy aspects of this final rule. The FAA will consider all comments received by the closing date and may amend this final rule because of those comments. \n\tExcept for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in 14 CFR 11.35, the FAA will post all comments received, without change, to https://www.regulations.gov, including any personal information you provide. The FAA will also post a report summarizing each substantive verbal contact received about this AD. \n\nConfidential Business Information \n\n\n\tConfidential Business Information (CBI) is commercial or financial information that is both customarily and actually treated as private by its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public disclosure. If your comments responsive to this AD contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this AD, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI as ''PROPIN.'' The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this AD. Submissions containing CBI should be sent to Kevin M. Clark, Aerospace Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking. \n\nRegulatory Flexibility Act \n\n\n\tThe requirements of the Regulatory Flexibility Act (RFA) do not apply when an agency finds good cause pursuant to 5 U.S.C. 553 to adopt a rule without prior notice and comment. Because FAA has determined that it has good cause to adopt this rule without notice and comment, RFA analysis is not required. \n\nCosts of Compliance \n\n\n\tThe FAA estimates that this AD affects 58 engines installed on airplanes of U.S. registry. \n\tThe FAA estimates the following costs to comply with this AD: \n\n\n\tEstimated Costs ---------------------------------------------------------------------------------------------------------------- \n\tCost per Cost on U.S. \n\tAction Labor cost Parts cost product operators ---------------------------------------------------------------------------------------------------------------- Replace EEC software.................. 2 work-hours x $85 per $0 $170 $9,860 \n\thour = $170. ---------------------------------------------------------------------------------------------------------------- \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 products 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\n((Page 17744)) \n\n\n\t(1) Is not a ''significant regulatory action'' under Executive Order 12866, and \n\t(2) Will not affect intrastate aviation in Alaska. \n\nList of Subjects in 14 CFR Part 39 \n\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.