{"abstract":"The FAA proposes to supersede Airworthiness Directive (AD) 2021-05-16, which applies to certain Pratt & Whitney Division (PW) PW4164, PW4164-1D, PW4168, PW4168-1D, PW4168A, PW4168A-1D, and PW4170 model turbofan engines. AD 2021-05-16 requires initial and repetitive replacements of the low-pressure turbine (LPT) 4th-stage air sealing ring segment assemblies with parts eligible for installation. AD 2021- 05-16 also requires initial and repetitive dimensional inspections of the LPT case for bulging and, depending on the results of the dimensional inspections, repair or replacement of the LPT case. Since the FAA issued AD 2021-05-16, the FAA was notified of an inadvertent omission in the LPT 4th-stage air sealing ring segment assembly part numbers. This proposed AD would correct this omission. The FAA is proposing this AD to address the unsafe condition on these products.","action":"Notice of proposed rulemaking (NPRM).","agencies":[{"raw_name":"DEPARTMENT OF TRANSPORTATION","name":"Transportation Department","id":492,"url":"https://www.federalregister.gov/agencies/transportation-department","json_url":"https://www.federalregister.gov/api/v1/agencies/492","parent_id":null,"slug":"transportation-department"},{"raw_name":"Federal Aviation Administration","name":"Federal Aviation Administration","id":159,"url":"https://www.federalregister.gov/agencies/federal-aviation-administration","json_url":"https://www.federalregister.gov/api/v1/agencies/159","parent_id":492,"slug":"federal-aviation-administration"}],"body_html_url":"https://www.federalregister.gov/documents/full_text/html/2021/07/23/2021-15518.html","cfr_references":[{"chapter":null,"citation_url":null,"part":39,"title":14}],"citation":"86 FR 38941","comment_url":null,"comments_close_on":"2021-09-07","correction_of":null,"corrections":[],"dates":"The FAA must receive comments on this proposed AD by September 7, 2021.","disposition_notes":null,"docket_ids":["Docket No. FAA-2021-0577","Project Identifier AD-2021-00470-E"],"dockets":[{"supporting_documents":[{"title":"Supporting AD Document","document_id":"FAA-2021-0577-0004"}],"agency_name":"FAA","documents":[{"comment_count":1,"comment_start_date":"2021-07-23","updated_at":"2023-02-28T17:28:44.830-05:00","comment_url":"https://www.regulations.gov/commenton/FAA-2021-0577-0001","allow_late_comments":null,"id":"FAA-2021-0577-0001","comment_end_date":"2021-09-08","regulations_dot_gov_open_for_comment":false}],"supporting_documents_count":1,"id":"FAA-2021-0577","title":"2021-NM-XXX-AD"}],"document_number":"2021-15518","effective_on":null,"end_page":38943,"executive_order_notes":null,"executive_order_number":null,"explanation":null,"full_text_xml_url":"https://www.federalregister.gov/documents/full_text/xml/2021/07/23/2021-15518.xml","html_url":"https://www.federalregister.gov/documents/2021/07/23/2021-15518/airworthiness-directives-pratt-and-whitney-division-turbofan-engines","images":{},"images_metadata":{},"json_url":"https://www.federalregister.gov/api/v1/documents/2021-15518?publication_date=2021-07-23","mods_url":"https://www.govinfo.gov/metadata/granule/FR-2021-07-23/2021-15518/mods.xml","not_received_for_publication":null,"page_length":3,"page_views":{"count":197,"last_updated":"2026-04-04 18:15:03 -0400"},"pdf_url":"https://www.govinfo.gov/content/pkg/FR-2021-07-23/pdf/2021-15518.pdf","presidential_document_number":null,"proclamation_number":null,"public_inspection_pdf_url":"https://public-inspection.federalregister.gov/2021-15518.pdf?1626957921","publication_date":"2021-07-23","raw_text_url":"https://www.federalregister.gov/documents/full_text/text/2021/07/23/2021-15518.txt","regulation_id_number_info":{"2120-AA64":{"issue":"202410","html_url":"https://www.federalregister.gov/regulations/2120-AA64/airworthiness-directives","title":"Airworthiness Directives","xml_url":"http://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202410&RIN=2120-AA64&operation=OPERATION_EXPORT_XML","priority_category":"Routine and Frequent"}},"regulation_id_numbers":["2120-AA64"],"regulations_dot_gov_info":{"supporting_documents":[{"title":"Supporting AD Document","document_id":"FAA-2021-0577-0004"}],"regulatory_plan":{"html_url":"https://www.federalregister.gov/regulations/2120-AA64/airworthiness-directives","title":"Airworthiness Directives"},"comments_count":1,"agency_id":"FAA","comments_url":"https://www.regulations.gov/docketBrowser?rpp=50&so=DESC&sb=postedDate&po=0&dct=PS&D=FAA-2021-0577","supporting_documents_count":1,"docket_id":"FAA-2021-0577","document_id":"FAA-2021-0577-0001","regulation_id_number":"2120-AA64","title":"2021-NM-XXX-AD","checked_regulationsdotgov_at":"2023-02-28T22:28:43Z"},"regulations_dot_gov_url":null,"significant":false,"signing_date":null,"start_page":38941,"subtype":null,"title":"Airworthiness Directives; Pratt & Whitney Division Turbofan Engines","toc_doc":"Pratt and Whitney Division Turbofan Engines","toc_subject":"Airworthiness Directives:\n","topics":["Air transportation","Aircraft","Aviation safety","Incorporation by reference","Safety"],"type":"Proposed Rule","volume":86}