{"abstract":"We are adopting a new airworthiness directive (AD) for the products listed above. This AD requires removing the 15th stage HPC disk within 12,000 cycles since new (CSN) or, for any disks that exceed 12,000 CSN after the effective date of this AD using a drawdown plan that includes a borescope inspection (BSI) or eddy current inspection (ECI) of the rim for cracks. This AD was prompted by multiple shop findings of cracked 15th stage HPC disks. We are issuing this AD to prevent cracks from propagating into the disk bolt holes, which could result in a failure of the 15th stage HPC disk, uncontained engine failure, and damage to the airplane.","action":"Final rule.","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/2011/08/04/2011-19476.html","cfr_references":[{"chapter":null,"citation_url":null,"part":39,"title":14}],"citation":"76 FR 47056","comment_url":null,"comments_close_on":null,"correction_of":null,"corrections":[],"dates":"This AD is effective September 8, 2011.","disposition_notes":null,"docket_ids":["Docket No. FAA-2010-1095","Directorate Identifier 2009-NE-40-AD","Amendment 39-16742","AD 2011-14-07"],"dockets":[],"document_number":"2011-19476","effective_on":"2011-09-08","end_page":47057,"executive_order_notes":null,"executive_order_number":null,"explanation":null,"full_text_xml_url":"https://www.federalregister.gov/documents/full_text/xml/2011/08/04/2011-19476.xml","html_url":"https://www.federalregister.gov/documents/2011/08/04/2011-19476/airworthiness-directives-pratt-and-whitney-pw-models-pw4074-and-pw4077-turbofan-engines","images":{},"images_metadata":{},"json_url":"https://www.federalregister.gov/api/v1/documents/2011-19476?publication_date=2011-08-04","mods_url":"https://www.govinfo.gov/metadata/granule/FR-2011-08-04/2011-19476/mods.xml","not_received_for_publication":null,"page_length":2,"page_views":{"count":134,"last_updated":"2026-04-04 20:15:04 -0400"},"pdf_url":"https://www.govinfo.gov/content/pkg/FR-2011-08-04/pdf/2011-19476.pdf","presidential_document_number":null,"proclamation_number":null,"public_inspection_pdf_url":null,"publication_date":"2011-08-04","raw_text_url":"https://www.federalregister.gov/documents/full_text/text/2011/08/04/2011-19476.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":"U.S. DOT/FAA - See Attachments","document_id":"FAA-2010-1095-0006"},{"title":"U.S. DOT/FAA  - See Attachments","document_id":"FAA-2010-1095-0004"}],"regulatory_plan":{"html_url":"https://www.federalregister.gov/regulations/2120-AA64/airworthiness-directives","title":"Airworthiness Directives"},"comments_url":"https://www.regulations.gov/docketBrowser?rpp=50&so=DESC&sb=postedDate&po=0&dct=PS&D=FAA-2010-1095","supporting_documents_count":2,"docket_id":"FAA-2010-1095","regulation_id_number":"2120-AA64","title":"2009-NE-40-AD","checked_regulationsdotgov_at":"2011-08-24T08:04:39Z"},"regulations_dot_gov_url":null,"significant":false,"signing_date":null,"start_page":47056,"subtype":null,"title":"Airworthiness Directives; Pratt & Whitney (PW) Models PW4074 and PW4077 Turbofan Engines","toc_doc":"Pratt and Whitney Models PW4074 and PW4077 Turbofan Engines","toc_subject":"Airworthiness Directives:","topics":["Air transportation","Aircraft","Aviation safety","Incorporation by reference","Safety"],"type":"Rule","volume":76}