{"abstract":"This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Boeing Model 747 series airplanes. This proposal would require repetitive high frequency eddy current inspections to find cracking of the bulkhead frame support at body station 2598 under the hinge support fittings of the horizontal stabilizer, and repair if cracking is found. This action is necessary to find and fix fatigue cracking in the frame support, which could result in inability of the structure to carry horizontal stabilizer flight loads and reduced controllability of the horizontal stabilizer. This action is intended to address the identified unsafe condition.","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/2001/02/21/01-4219.html","cfr_references":[{"chapter":null,"citation_url":null,"part":39,"title":14}],"citation":"66 FR 10974","comment_url":null,"comments_close_on":"2001-04-09","correction_of":null,"corrections":[],"dates":"Comments must be received by April 9, 2001.","disposition_notes":null,"docket_ids":["Docket No. 2000-NM-251-AD"],"dockets":[],"document_number":"01-4219","effective_on":null,"end_page":10976,"executive_order_notes":null,"executive_order_number":null,"explanation":null,"full_text_xml_url":"https://www.federalregister.gov/documents/full_text/xml/2001/02/21/01-4219.xml","html_url":"https://www.federalregister.gov/documents/2001/02/21/01-4219/airworthiness-directives-boeing-model-747-series-airplanes","images":{},"images_metadata":{},"json_url":"https://www.federalregister.gov/api/v1/documents/01-4219?publication_date=2001-02-21","mods_url":"https://www.govinfo.gov/metadata/granule/FR-2001-02-21/01-4219/mods.xml","not_received_for_publication":null,"page_length":3,"page_views":{"count":1,"last_updated":"2026-04-04 18:15:03 -0400"},"pdf_url":"https://www.govinfo.gov/content/pkg/FR-2001-02-21/pdf/01-4219.pdf","presidential_document_number":null,"proclamation_number":null,"public_inspection_pdf_url":null,"publication_date":"2001-02-21","raw_text_url":"https://www.federalregister.gov/documents/full_text/text/2001/02/21/01-4219.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":{},"regulations_dot_gov_url":null,"significant":false,"signing_date":null,"start_page":10974,"subtype":null,"title":"Airworthiness Directives; Boeing Model 747 Series Airplanes","toc_doc":"Boeing","toc_subject":"Airworthiness directives:","topics":["Air transportation","Aircraft","Aviation safety","Safety"],"type":"Proposed Rule","volume":66}