{"abstract":"We propose to adopt a new airworthiness directive (AD) for Model 747-400, 747-400D, and 747-400F series airplanes. This proposed AD would require installing a hot short protector (HSP) for the fuel quantity indicating system (FQIS) of the center fuel tank and, for certain airplanes, the horizontal stabilizer fuel tank. This proposed AD results from fuel system reviews conducted by the manufacturer. We are proposing this AD to prevent an electrical hot short from a source outside the FQIS to the densitometer wiring from causing failure of the FQIS densitometer resistors, which could result in an ignition source inside the center or horizontal stabilizer fuel tanks. An ignition source, in combination with flammable fuel vapors, could result in a fuel tank explosion and consequent loss of 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/2010/02/11/2010-2992.html","cfr_references":[{"chapter":null,"citation_url":null,"part":39,"title":14}],"citation":"75 FR 6821","comment_url":null,"comments_close_on":"2010-03-29","correction_of":null,"corrections":[],"dates":"We must receive comments on this proposed AD by March 29, 2010.","disposition_notes":null,"docket_ids":["Docket No. FAA-2010-0035","Directorate Identifier 2009-NM-066-AD"],"dockets":[],"document_number":"2010-2992","effective_on":null,"end_page":6823,"executive_order_notes":null,"executive_order_number":null,"full_text_xml_url":"https://www.federalregister.gov/documents/full_text/xml/2010/02/11/2010-2992.xml","html_url":"https://www.federalregister.gov/documents/2010/02/11/2010-2992/airworthiness-directives-the-boeing-company-model-747-400-747-400d-and-747-400f-series-airplanes","images":{},"images_metadata":{},"json_url":"https://www.federalregister.gov/api/v1/documents/2010-2992?publication_date=2010-02-11","mods_url":"https://www.govinfo.gov/metadata/granule/FR-2010-02-11/2010-2992/mods.xml","not_received_for_publication":null,"page_length":3,"page_views":{"count":89,"last_updated":"2026-07-26 06:15:03 -0400"},"pdf_url":"https://www.govinfo.gov/content/pkg/FR-2010-02-11/pdf/2010-2992.pdf","presidential_document_number":null,"proclamation_number":null,"public_inspection_pdf_url":null,"publication_date":"2010-02-11","raw_text_url":"https://www.federalregister.gov/documents/full_text/text/2010/02/11/2010-2992.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":"2010-02-11T16:00:38Z"},"regulations_dot_gov_url":null,"significant":false,"signing_date":null,"start_page":6821,"subtype":null,"title":"Airworthiness Directives; The Boeing Company Model 747-400, 747-400D, and 747-400F Series Airplanes","toc_doc":"Boeing Company Model 747 400, 747 400D, and 747 400F Series Airplanes","toc_subject":"Airworthiness Directives:","topics":["Air transportation","Aircraft","Aviation safety","Incorporation by reference","Safety"],"type":"Proposed Rule","volume":75}