Background \n\n\n\tThe European Union Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued EASA AD 2020-0226-E, dated October 16, 2020 (referred to after this as ''the MCAI''), to address an unsafe condition for the specified products. The MCAI states: \n\n\n\tCracks have been reported at different positions on two affected parts, both installed on Slingsby T67 ''Firefly'' aeroplanes. One crack was found during scheduled inspection, the other crack during an unscheduled inspection after abnormal vibrations occurred. Both cases are under investigation by Hoffmann Propeller. \n\tThis condition, if not detected and corrected, could lead to in- flight propeller detachment, possibly resulting in damage to the airplane and/or injury to persons on the ground. \n\tTo address this potential unsafe condition, Hoffmann issued the SB (service bulletin), providing applicable instructions. \n\tFor the reasons described above, this (EASA) AD requires inspections of affected parts and, depending on findings, replacement, and introduces a life limit for affected parts. This (EASA) AD also requires, for certain aeroplanes, amendment of the applicable Aircraft Flight Manual (AFM). \n\n\n\tYou may obtain further information by examining the MCAI in the AD docket at https://www.regulations.gov by searching for and locating Docket No. FAA-2020-1104. \n\nFAA's Determination \n\n\n\tThe FAA is issuing this AD because the agency has determined the unsafe condition described previously is likely to exist or develop in other products of the same type design. \n\nRelated Service Information Under 1 CFR Part 51 \n\n\n\tThe FAA reviewed Hoffmann Propeller GmbH & Co. KG Service Bulletin SB E53, Rev. B, dated October 14, 2020. This service information specifies procedures for visual and NDT inspections of the propeller hub for cracks. This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in ADDRESSES. \n\nAD Requirements \n\n\n\tThis AD requires amending the existing AFM with abnormal propeller vibration instructions. This AD also requires visual inspection and NDT inspection of the propeller hub and, depending on the results of the inspections, replacement of the propeller hub with a part eligible for installation. This AD also requires replacement of the propeller hub before exceeding 30 years since the date of manufacture or within 30 days after the effective date of this AD, whichever occurs later. \n\nDifferences Between the AD and the MCAI \n\n\n\tEASA AD 2020-0226-E, dated October 16, 2020, applies to Hoffmann HO-V 72 propellers with propeller hub HO-V 72 ( ) ( )-( )-( ) that have been used or are expected to be used for aerobatic maneuvers. This AD applies to all Hoffmann model HO-V 72 propellers regardless of their use. \n\n((Page 78703)) \n\n\n\tEASA AD 2020-0226-E, dated October 16, 2020, defines the life of the propeller hub as 30 years since the first installation on the airplane. This AD defines the life of the propeller hub as 30 years since the date of manufacture because the installation history of the propeller might be unknown. \n\nInterim Action \n\n\n\tThe FAA considers this AD interim action. This unsafe condition is still under investigation by the manufacturer and, depending on the results of that investigation, the FAA may consider further rulemaking action. \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 noticeand seeking comment prior to issuance. Further, section 553(d) of the APA authorizes agencies to make rules effective in less than thirty 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 to adoption. The FAA has found that the risk to the flying public justifies foregoing notice and comment prior to adoption of this rule. During a scheduled inspection, a crack was found by an operator on a propeller hub. A second crack was found on another propeller hub during an unscheduled inspection by an operator after abnormal vibrations occurred in-flight. Hoffmann Propeller immediately issued service information instructing operators to visually inspect the hub for cracks before the next flight while the cause of the cracks are under investigation. \n\tA crack in the propeller hub can result in the loss of a propeller blade, resulting in an imbalance in the entire engine which can render the aircraft uncontrollable. The FAA considers a crack in the propeller hub an urgent safety issue that requires an immediate action to avoid potential loss of the airplane. Accordingly, 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). In 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-2020-1104 and Project Identifier MCAI-2020-01421-P at the beginning of your comments. The most helpful comments reference a specific portion of the 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 Michael Schwetz, Aviation Safety Engineer, Boston ACO 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 35 propellers installed on airplanesof 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 ---------------------------------------------------------------------------------------------------------------- Amend AFM.......................... 1 work-hour x $85 per hour $0 $85 $2,975 \n\t= $85. Visually inspect propeller hub..... 1 work-hour x $85 per hour 0 85 2,975 \n\t= $85. NDT inspect propeller hub.......... 8 work-hours x $85 per hour 0 680 23,800 \n\t= $680. ---------------------------------------------------------------------------------------------------------------- \n\n\n\tThe FAA estimates the following costs to do any necessary replacement that would be required based on the results of the inspections. The agency has no way of determining the number of aircraft that might need this replacement: \n\n((Page 78704)) \n\n\n\n\n\n\n\tOn-Condition Costs ---------------------------------------------------------------------------------------------------------------- \n\tCost per \n\tAction Labor cost Parts cost product ---------------------------------------------------------------------------------------------------------------- Replace propeller hub......................... 5 work-hours x $85 per hour = $1,600 $2,025 \n\t$425. ---------------------------------------------------------------------------------------------------------------- \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.For 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.