{"id":"F2010L00062","name":"AD/B747/157 Amdt 2 - P&W JT9D Aft Engine Mount Tangential Link","slug":"ad-b747-157-amdt-2-p-w-jt9d-aft-engine-mount-tangential-link","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":122742,"registerId":"commonwealth-F2010L00062-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 747 Series Aeroplanes","sectionType":"division","heading":"Boeing 747 Series Aeroplanes","content":"### Boeing 747 Series Aeroplanes\n\n| AD/B747/157 Amdt 2 | P&W JT9D Aft Engine Mount Tangential Link | 1/2010 |\n| ------------------ | ----------------------------------------- | ------ |\n\n| Applicability: | Model 747 series aeroplanes with line positions 1 to 668, powered by Pratt & Whitney JT9D series engines except JT9D-70.                                                                                                                                                                                                                                                                                                                                                                 |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Terminating action in accordance with the technical requirements of paragraph (b) of FAA AD 99-20-09 Amdt 39-11339.Note: Boeing Service Bulletins 747-71-2206 and 747-71A2277 Revision 2, or later Revisions, refer.                                                                                                                                                                                                                                                                     |\n| Compliance:    | Prior to initial issue of an Australian certificate of airworthiness.                                                                                                                                                                                                                                                                                                                                                                                                                    |\n|                | This Amendment becomes effective on 8 January 2010.                                                                                                                                                                                                                                                                                                                                                                                                                                      |\n| Background:    | The tangential link upper bolt was found to have backed out following lubrication of the threads and/or inadequate nut torque which allowed the nut to rotate and disengage. The original issue of this Directive nominated FAA AD 96-03-01 and became effective on 13 March 1996.Amendment 1 specified Revision 1 of FAA AD 96-03-01 and became effective on20 June 1996.This Amendment specifies FAA AD 99-20-09 which superseded 96-03-01 and specified mandatory terminating action. |\n\n![](image.001.png)\n\nMike Higgins  \nDelegate of the Civil Aviation Safety Authority\n\n5 January 2010","sortOrder":0},{"sectionNumber":"AD/B747/157 Amdt 2","sectionType":"part","heading":"AD/B747/157 Amdt 2","content":"## AD/B747/157 Amdt 2","sortOrder":1},{"sectionNumber":"P&W JT9D Aft Engine Mount Tangential Lin","sectionType":"part","heading":"P&W JT9D Aft Engine Mount Tangential Link","content":"## P&W JT9D Aft Engine Mount Tangential Link","sortOrder":2},{"sectionNumber":"1/2010","sectionType":"part","heading":"1/2010","content":"## 1/2010","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a routine amendment to an existing Airworthiness Directive. It updates the referenced FAA directive from 96-03-01 to 99-20-09 to reflect the latest mandatory terminating action. The scope remains tightly focused on the specific engine mount hardware defect it was originally designed to address."},"complexity_factors":["Single, highly specific applicability clause (one aircraft model range, specific line positions, specific engine type with one exclusion)","Single requirement referencing an external FAA directive (AD 99-20-09) rather than spelling out technical steps","No defined terms section — all technical terms are industry standard","No conditional logic or nested exceptions","Short document (approximately 200 words of substantive content)","Clear compliance deadline (prior to airworthiness certificate issuance)"],"plain_english_summary":"This CASA Airworthiness Directive orders owners/operators of Boeing 747s built at line positions 1–668 with Pratt & Whitney JT9D engines (except -70) to replace or modify the bolt assembly on the aft engine mount tangential link.  \n\nThe mandatory fix—required before an Australian certificate of airworthiness—is a terminating action to stop bolt loosening that could lead to engine separation or structural failure, protecting flight safety."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This amendment replaces earlier directives (FAA AD 96-03-01 and its Revision 1) by specifying FAA AD 99-20-09, which supersedes the prior ADs and mandates a terminating action. The applicability (line positions and engine exclusion) is retained from the instrument text, but the required technical remedy is updated to the terminating modification specified in the newer FAA AD."},"complexity_factors":["Direct cross-reference to an external FAA AD (99-20-09) for the detailed technical and terminating action, requiring access to and reliance on that document.","References to specific Boeing service bulletins (747-71-2206 and 747-71A2277 Revision 2 or later) for modification instructions, creating dependency on vendor documents and revision control.","Narrow applicability (airframe line positions 1–668 and JT9D engine series excluding -70), requiring operators to determine applicability precisely.","Timing constraint limiting compliance to prior to initial issue of an Australian Certificate of Airworthiness, affecting import/initial-certification workflows.","Regulatory history and supersession (replaces earlier FAA ADs 96-03-01 and its Revision 1), which may require checking legacy compliance records.","Mandated ‘terminating action’ removes discretionary alternatives for compliance once applicable, concentrating compliance on a specific modification."],"plain_english_summary":"**AD/B747/157 Amdt 2** requires Boeing 747 airframes (line positions 1–668) with Pratt & Whitney JT9D engines (except the -70) to carry out the terminating action set out in FAA AD 99-20-09 (and the referenced Boeing service bulletins) before the aeroplane can receive an Australian certificate of airworthiness. It responds to incidents where the aft engine mount tangential link upper bolt backed out; the practical effect is a mandatory maintenance/modification that affected aircraft owners/operators must complete at their cost."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-157-amdt-2-p-w-jt9d-aft-engine-mount-tangential-link","history":"/api/acts/ad-b747-157-amdt-2-p-w-jt9d-aft-engine-mount-tangential-link/history","analysis":"/api/acts/ad-b747-157-amdt-2-p-w-jt9d-aft-engine-mount-tangential-link/analysis","conflicts":"/api/acts/ad-b747-157-amdt-2-p-w-jt9d-aft-engine-mount-tangential-link/conflicts","importantCases":"/api/acts/ad-b747-157-amdt-2-p-w-jt9d-aft-engine-mount-tangential-link/important-cases","documents":"/api/acts/ad-b747-157-amdt-2-p-w-jt9d-aft-engine-mount-tangential-link/documents"}}