{"abstract":"The FAA proposes to adopt a new airworthiness directive (AD) for PW PW4164, PW4168, and PW4168A turbofan engines with certain low pressure turbine (LPT) stage 4 disks, part number (P/N) 51N404, installed. This proposed AD would require removing certain LPT stage 4 disks, listed by serial number at the next piece-part exposure or within 7,500 cycles-since-new (CSN), whichever occurs first. This proposed AD results from a report of improperly manufactured LPT stage 4 disks. We are proposing this AD to prevent an uncontained engine failure due to low-cycle fatigue (LCF), which could result in damage to the airplane.","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/2007/05/21/E7-9697.html","cfr_references":[{"chapter":null,"citation_url":null,"part":39,"title":14}],"citation":"72 FR 28459","comment_url":null,"comments_close_on":"2007-07-20","correction_of":null,"corrections":[],"dates":"We must receive any comments on this proposed AD by July 20, 2007.","disposition_notes":null,"docket_ids":["Docket No. FAA-2007-27230","Directorate Identifier 2007-NE-04-AD"],"dockets":[],"document_number":"E7-9697","effective_on":null,"end_page":28461,"executive_order_notes":null,"executive_order_number":null,"explanation":null,"full_text_xml_url":"https://www.federalregister.gov/documents/full_text/xml/2007/05/21/E7-9697.xml","html_url":"https://www.federalregister.gov/documents/2007/05/21/E7-9697/airworthiness-directives-pratt-and-whitney-pw-pw4164-pw4168-and-pw4168a-turbofan-engines","images":{},"images_metadata":{},"json_url":"https://www.federalregister.gov/api/v1/documents/E7-9697?publication_date=2007-05-21","mods_url":"https://www.govinfo.gov/metadata/granule/FR-2007-05-21/E7-9697/mods.xml","not_received_for_publication":null,"page_length":3,"page_views":{"count":116,"last_updated":"2026-04-04 16:15:04 -0400"},"pdf_url":"https://www.govinfo.gov/content/pkg/FR-2007-05-21/pdf/E7-9697.pdf","presidential_document_number":null,"proclamation_number":null,"public_inspection_pdf_url":null,"publication_date":"2007-05-21","raw_text_url":"https://www.federalregister.gov/documents/full_text/text/2007/05/21/E7-9697.txt","regulation_id_number_info":{"2120-AA64":{"issue":"202504","html_url":"https://www.federalregister.gov/regulations/2120-AA64/airworthiness-directives","title":"Airworthiness Directives","xml_url":"http://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202504&RIN=2120-AA64&operation=OPERATION_EXPORT_XML","priority_category":"Routine and Frequent"}},"regulation_id_numbers":["2120-AA64"],"regulations_dot_gov_info":{"checked_regulationsdotgov_at":"2011-11-12T21:51:16Z"},"regulations_dot_gov_url":null,"significant":false,"signing_date":null,"start_page":28459,"subtype":null,"title":"Airworthiness Directives; Pratt & Whitney (PW) PW4164, PW4168, and PW4168A Turbofan Engines","toc_doc":"Pratt  Whitney","toc_subject":"Airworthiness directives:","topics":["Air transportation","Aircraft","Aviation safety","Safety"],"type":"Proposed Rule","volume":72}