Background \n\n\n\tThe FAA was informed by the manufacturer that a PGB development test was stopped due to high vibration caused by a fatigue crack that initiated in the PGB shaft and carrier assembly. The fatigue crack initiated in a broach slot of the PGB shaft. The manufacturer determined the need to apply life limits to the PGB shaft and carrier assembly, which has not previously been a life-limited part. To track these parts, the manufacturer determined the need to assign usage hours to PGB shaft and carrier assemblies that already have time in service. \n\tAn examination by the manufacturer of Material Review Board records also identified two PGB shaft and carrier assemblies that were accepted with reduced material properties prior to their reclassification as a life limited part requiring reduced lives. The manufacturer applied reduced life limits to these PGB shaft and carrier assemblies. In addition, a review of shop repair records by the manufacturer identified a number of PGB shaft and carrier assemblies that received a keylock stud repair introducing unacceptable unused ''keyslots'' that can cause stress concentration and reduced life. The manufacturer requires either rework or removal of these PGB shaft and carrier assemblies. \n\tThe FAA determined that updating the ALS of the RRC AE 2100D3 Maintenance Manual and the continued airworthiness maintenance program for the affected RRC 2100D3 model turbofan engines is the most effective way to address the unsafe condition pertaining to fatigue cracks in the PGB shaft and carrier assembly. These ALS updates apply life limits to PGB shaft and carrier assemblies installed on RRC AE 2100D3 model turbofan engines. Certain part numbered PGB shaft and carrier assemblies with reduced material properties were assigned reduced life limits. To track these parts, the ALS updates require assignment of usage hours to the PGB shaft and carrier assembly no later than the next engine shop visit for all RRC AE model turboprop engines. Depending on the part and serial number of the PGB shaft and carrier assembly, the updates to the ALS requires reidentification or removal of the PGB shaft and carrier assembly. \n\tThis condition, if not addressed, could result in loss of the propeller, damage to the engine, and damage to the airplane. The FAA is issuing this AD to address the unsafe condition on these products. \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 Under 1 CFR Part 51 \n\n\n\tThe FAA reviewed Task 05-11-00-800-801, dated June 20, 2018 of the Airworthiness Limitations System Description Section-801, RRC AE 2100D3 Maintenance Manual (''Task 05-11-00-800-801'') and Task 05-12-11-800- 802, dated June 1, 2020 of the Propeller Gearbox System ComponentLife Limits Systems Description Section-802, RRC AE 2100D3 Maintenance Manual (''Task 05-12-11-800-802''). \n\tTask 05-11-00-800-801 specifies: (1) Assignment of usage hours to the PGB shaft and carrier assemblies; (2) reworking confirmed blind hole configured PGB shaft and carrier \n\n((Page 60892)) \n\nassemblies to the through-hole controlled keyslot configuration; and (3) reidentifying through-hole PGB shaft and carrier assemblies to a new part number. \n\tTask 05-12-11-800-802 specifies: (1) Assignment of new life limits to the PGB shaft and carrier assemblies; (2) decreasing the life limit for PGB shaft and carrier assemblies found to have reduced material properties; and (3) replacing PGB shaft and carrier assemblies that have received a keylock stud repair which introduced unacceptable unused keyslots. \n\tThis 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 the ADDRESSES section. \n\nOther Related Service Information \n\n\n\tThe FAA reviewed RRC Alert Service Bulletin (ASB) AE2100D3-A-72- 256, Revision 3, dated January 15, 2018; AE 2100D3-A-72-313, Revision 1, dated May 28, 2018; RRC ASB AE 2100D3-A-72-314, Revision 0, dated January 15, 2018; RRC ASB AE 2100D3-A-72-315, Revision 2, dated July 13, 2018; RRC ASB AE 2100D3-A-72-324, Revision 0, dated November 26, 2019; and RRC ASB AE 2100D3-A-72-325, Revision 0, dated November 26, 2019. \n\tRRC ASB AE2100D3-A-72-256, Revision 3, dated January 15, 2018, describes procedures for re-work of certain PGB shaft and carrier assemblies. \n\tRRC ASB AE 2100D3-A-72-313 describes procedures for assigning usage hours to the PGB shaft and carrier assemblies. \n\tRRC ASB AE 2100D3-A-72-314 describes procedures for reworking PGB shaft and carrier assemblies from the blind hole to the preferred through hole controlled keyslot configuration. \n\tRRC ASB AE 2100D3-A-72-315 describes procedures for reidentifying PGB shaftand carrier assemblies which are of the preferred through hole controlled keyslot configuration. \n\tRRC ASB AE 2100D3-A-72-324 establishes a decrease in life limit of 10,525 hours for PGB shaft and carrier assemblies, with (S/Ns) CU32063 and CU32071, which were found to have reduced material properties. \n\tRRC ASB AE 2100D3-A-72-325 describes procedures for reworking or replacing PGB shaft and carrier assemblies, listed in Table 1 of RRC ASB AE 2100D3-72-A-325, that have received a keylock stud repair which introduced unacceptable unused keyslots. \n\nAD Requirements \n\n\n\tThis AD requires revising the ALS of the AE 2100D3 Maintenance Manual and the operator's approved continuous airworthiness maintenance program. \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 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 authorizes agencies to make rules effective in less than 30 days, upon a finding of good cause. \n\tThe FAA has found the risk to the flying public justifies waiving notice and comment prior to adoption of this rule because no domestic operators use this product. It is unlikely that the FAA will receive any adverse comments or useful information about this AD from U.S. operators. Accordingly, notice and opportunity for prior public comment are unnecessary, pursuant to 5 U.S.C. 553(b)(3)(B). In addition, for the foregoing reasons, 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\tThe 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-2020-0853 and Project Identifier AD-2020-00588-E at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, 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 FAA will also post a report summarizing each substantive verbal contact received about this final rule. \n\nConfidential Business Information \n\n\n\tConfidential Business Information (CBI) is commercial orfinancial 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 final rule 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 final rule, 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 final rule. Submissions containing CBI should be sent to Kyri Zaroyiannis, Aerospace Engineer, Chicago ACO, FAA, 2300 E Devon Ave., Des Plaines, IL 60018. 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 the 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 0 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 ---------------------------------------------------------------------------------------------------------------- Insert Task 05-12-11-800-801 into RRC 0.5 work-hours x $85 per $0 $42.50$0 \n\tAE 2100D3 Maintenance Manual. hour = $42.50. \n\n((Page 60893)) \n\n\n\nInsert Task 05-12-11-800-802 into RRC 0.5 work-hours x $85 per 0 42.50 0 \n\tAE 2100D3 Maintenance Manual. hour = $42.50. ---------------------------------------------------------------------------------------------------------------- \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\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.