{"id":"F2009L02838","name":"AD/B747/168 Amdt 3 - Engine Pylon Aft Torque Bulkhead","slug":"ad-b747-168-amdt-3-engine-pylon-aft-torque-bulkhead","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":80129,"registerId":"commonwealth-F2009L02838-current","compilationNumber":null,"startDate":"2026-04-02","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/B747/168 Amdt 3 | Engine Pylon Aft Torque Bulkhead | 8/2009 |\n| ------------------ | -------------------------------- | ------ |\n\n| Applicability: | Model 747 series aircraft, as listed in Groups 1, 2, and 5 of Boeing Alert Service Bulletin (ASB) 747-54A2184, Revision 1, dated 6 May 1999.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Requirement:   | Action in accordance with the technical requirements of FAA AD 2000-12-16 Amdt 39-11794.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |\n| Compliance:    | As specified in the Requirement document with a revised effective date of7 September 2000.The compliance remains unchanged by issue of the Directive.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |\n|                | This Amendment becomes effective on 30 July 2009.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |\n| Background:    | The FAA received two reports of cracking of the aft torque bulkhead at the number 1 and number 2 engine pylons. This cracking occurred on a Boeing model 747-200F series aircraft powered by Rolls Royce model RB211 series engines. Cracking of the aft torque bulkhead at the engine pylons, if not detected and corrected in a timely manner, could result in failure of a pylon and consequent separation of the engine from the wing.Amendment 1 was prompted by a report of cracking found in the aft torque bulkheads of the outboard nacelle struts, and by the availability of new service instructions for detecting fatigue cracking.Amendment 2 expanded applicability to include additional aircraft while removing certain other aircraft from applicability. This amendment also required accomplishment of a new terminating action.Amendment 3 is issued to correct the issue date of the related Boeing ASB. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n18 June 2009","sortOrder":0},{"sectionNumber":"AD/B747/168 Amdt 3","sectionType":"part","heading":"AD/B747/168 Amdt 3","content":"## AD/B747/168 Amdt 3","sortOrder":1},{"sectionNumber":"Engine Pylon Aft Torque Bulkhead","sectionType":"part","heading":"Engine Pylon Aft Torque Bulkhead","content":"## Engine Pylon Aft Torque Bulkhead","sortOrder":2},{"sectionNumber":"8/2009","sectionType":"part","heading":"8/2009","content":"## 8/2009","sortOrder":3}],"analysis":{"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"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"Amendment 3 does not change substantive requirements: it corrects the issue date of the Boeing service bulletin and confirms that compliance remains unchanged (Requirement; Amendment 3). Earlier amendments did alter scope—Amendment 1 added detection instructions and Amendment 2 expanded applicability and required a new terminating action (Background)—but this Amendment only corrects the ASB date."},"complexity_factors":["Cross‑reference to external FAA AD 2000‑12‑16 (Requirement) — operators must follow an external directive rather than a self‑contained domestic text.","Applicability tied to specific groups in Boeing ASB 747‑54A2184 Rev 1 (Applicability) — requires operators to check ASB group lists to determine if their aircraft are affected.","Technical subject matter (Background) — fatigue cracking detection and repair requires specialist inspections and possible structural repair, increasing operational and maintenance complexity.","Multiple amendment history (Background) — Amendments 1 and 2 introduced new inspection instructions, changed applicability and added a terminating action, so tracing current obligations requires reviewing amendment history.","Compliance timing and effective dates (Compliance) — the instrument corrects and restates dates (effective 30 July 2009; revised effective date 7 September 2000), which can create administrative confusion for recordkeeping.","Operator cost allocation (Requirement/Background) — the mandate imposes inspection/repair work on aircraft operators (they must perform actions in the FAA AD), so direct costs and downtime fall to operators.","Low administrative discretion (Requirement) — the directive requires action 'in accordance with' the FAA AD, leaving little scope for alternative compliance without explicit allowance in the referenced AD."],"plain_english_summary":"This amendment tells operators of certain Boeing 747s (those listed in Groups 1, 2 and 5 of Boeing ASB 747‑54A2184 Rev 1) to carry out the technical actions required by FAA AD 2000‑12‑16. Mechanically it corrects the Boeing service‑bulletin issue date and reaffirms unchanged compliance obligations to detect and repair fatigue cracking in aft engine‑pylon torque bulkheads that, if undetected, could lead to pylon failure and engine separation."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is Amendment 3 to an existing Airworthiness Directive. The amendment explicitly states it is issued 'to correct the issue date of the related Boeing ASB' and confirms 'the compliance remains unchanged.' The scope has remained consistent since the original AD: ensuring structural integrity of engine pylons on affected Boeing 747 aircraft. Previous amendments expanded applicability (Amendment 2) and added new inspection requirements (Amendment 1), but this amendment makes no substantive change to scope."},"complexity_factors":["Short, single-purpose instrument (approximately 250 words)","Only 1 defined term implicitly referenced (the Boeing ASB)","Heavy reliance on external documents — the actual technical requirements are contained in FAA AD 2000-12-16 and Boeing ASB 747-54A2184, not reproduced here","Simple amendment structure: corrects a date error without altering substantive requirements","No nested conditional logic or exceptions within the instrument itself","Clear applicability table format with straightforward compliance dates"],"plain_english_summary":"This CASA Airworthiness Directive mandates operators of certain Boeing 747s to inspect and, if necessary, repair or replace the aft torque bulkhead per FAA AD 2000-12-16 and Boeing Alert Service Bulletin 747-54A2184 Rev 1 to prevent fatigue cracks that could lead to engine pylon failure and engine separation.\n\nAmendment 3 does not change requirements; it only corrects the issue date of the referenced Boeing service bulletin."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-168-amdt-3-engine-pylon-aft-torque-bulkhead","history":"/api/acts/ad-b747-168-amdt-3-engine-pylon-aft-torque-bulkhead/history","analysis":"/api/acts/ad-b747-168-amdt-3-engine-pylon-aft-torque-bulkhead/analysis","conflicts":"/api/acts/ad-b747-168-amdt-3-engine-pylon-aft-torque-bulkhead/conflicts","importantCases":"/api/acts/ad-b747-168-amdt-3-engine-pylon-aft-torque-bulkhead/important-cases","documents":"/api/acts/ad-b747-168-amdt-3-engine-pylon-aft-torque-bulkhead/documents"}}