Background \n\n\n\tOn February 23, 2021, the FAA issued Emergency AD 2021-05-51 (the emergency AD), which requires performing a TAI inspection for cracks in certain 1st-stage LPC blades and removal of those blades that fail inspection. The FAA sent the emergency AD to all known U.S. owners and operators of these engines. That action was prompted by the in-flight failure of a 1st-stage LPC blade on a PW4077 model turbofan engine resulting in an engine fire during flight. This condition, if not addressed, could result in 1st-stage LPC blade release, damage to the engine, and damage to the airplane. \n\nFAA's Determination \n\n\n\tThe FAA is issuing this AD because the agency 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\nRelated Service Information \n\n\n\tThe FAA reviewed Pratt & Whitney Alert Service Bulletin (ASB) PW4G- 112-A72-268,Revision No. 7, dated September 6, 2018. The ASB describes procedures for performing TAI inspections of 1st-stage LPC blades. \n\nAD Requirements \n\n\n\tThis AD requires performing a TAI inspection for cracks in certain 1st-stage LPC blades and removal of those blades that fail inspection. \n\nInterim Action \n\n\n\tThe FAA considers this AD to be an interim action. The FAA anticipates that further AD action will follow. \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. 551 et seq.) 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 to the public interest.'' Under this section, an agency, upon finding good cause, may issue a final rule without providing notice and seeking comment prior to issuance. Further, section 553(d) of the APA authorizesagencies to make rules effective in less than thirty days, upon a finding of good cause. \n\tAn unsafe condition exists that required the immediate adoption of Emergency AD 2021-05-51, issued on February 23, 2021, to all known U.S. owners and operators of these engines. The FAA found that the risk to the flying public justified waiving notice and comment prior to adoption of this rule. On February 20, 2021, a United Airlines Boeing Model 777-222 airplane, equipped with two PW4077 model turbofan engines, on a flight from Denver, Colorado to Honolulu, Hawaii, experienced a 1st-stage LPC blade failure on the number 2 engine. This engine failure resulted in the separation of the fan inlet and cowling from the airplane, an engine fire, and damage to the airplane. The airplane was forced to return to the airport of departure. The unsafe condition, caused by the failure of the 1st-stage LPC blade, could result in 1st-stage LPC blade release, damage to the engine, and damage to the airplane.The FAA considers inspection and removal of those blades that fail inspection to be an urgent safety issue. Inspection of the 1st-stage LPC blade for cracks must be accomplished before further flight after the effective date of this AD. These conditions still exist, therefore, notice and opportunity for prior public comment are impracticable and contrary to the public interest pursuant to 5 U.S.C. 553(b)(3)(B). \n\n((Page 13446)) \n\n\n\tIn addition, 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, for the same reasons the FAA found good cause to forego notice and comment. \n\nComments Invited \n\n\n\tThe FAA invites you to send any written data, views, or arguments about this final rule. Send your comments to an address listed under ADDRESSES. Include the docket number FAA-2021-0136 and Project Identifier AD-2021-00188-E at the beginning of your comments. The most helpful comments reference a specific portion ofthe final rule, explain the reason for any recommended change, and include supporting data. 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 agency will also post a report summarizing each substantive verbal contact received about this final rule. \n\nConfidential Business Information \n\n\n\tCBI 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 Carol Nguyen, Aviation Safety 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 prior notice and comment, RFA analysis is not required. \n\nCosts of Compliance \n\n\n\tThe FAA estimates that this AD affects 104 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 ---------------------------------------------------------------------------------------------------------------- TAI of 1st-stage LPC blades........... 22 work-hours x $85 per $0 $1,870 $194,480 \n\thour = $1,870. ---------------------------------------------------------------------------------------------------------------- \n\n\n\tThe FAA estimates the following costs to do any necessary replacement that would be required based on the results of the inspection. The agency has no way of determining the number of aircraft that might need this replacement: \n\n\n\tOn-Condition Costs ---------------------------------------------------------------------------------------------------------------- \n\tCost per \n\tAction Labor cost Parts cost product ---------------------------------------------------------------------------------------------------------------- Replace 1st-stage LPC blade................... 0 work-hours x $85 per hour = $0 $125,000 $125,000 ---------------------------------------------------------------------------------------------------------------- \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 SubtitleVII, 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\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.