{"id":"F2006B03219","name":"AD/B747/39 Amdt 2 - Nacelle Strut Diagonal Brace Fuse Pin","slug":"ad-b747-39-amdt-2-nacelle-strut-diagonal-brace-fuse-pin","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42591,"registerId":"commonwealth-F2006B03219-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/39 Amdt 2 - Nacelle Strut Diagonal Brace Fuse Pin","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBoeing 747 Series Aeroplanes\n\nAD/B747/39\n\nAmdt 2\n\n  \nNacelle Strut Diagonal Brace Fuse Pin 6/93\n\nDM\n\nApplicability: Boeing 747 aircraft all models.\n\nRequirement: Action IAW the technical requirements of FAA AD 93-03-14 Amdt 39-8518.\n\nNote: Note Boeing SBs 747-54-2066 Rev. 2, 747-54-2101 Rev. 1 and ASB 747-54-\n\nA2153 refer.\n\nCompliance: As specified in the Requirement Document with a revised effective date of 21 April 1993.\n\nCompliance for the initial issue of this Directive was in accordance with SB 747-54- 2101, and the effective date for Amendment 1 was 04 March 1993.\n\nBackground: The manufacturer had received reports of in service cracking of the inboard nacelle strut diagonal brace fuse pins. Amendment 1 was raised in response to the issue of a new FAA AD which combined the requirements of two previous ADs and added repetitive inspections of forward and aft bottle pins in the outboard nacelle strut and the aft bulkhead fuse pins in the inboard and the outboard nacelle struts. Amendment 2 is raised as the result of textural errors in FAA AD 93-01-05 which is superseded by the current Requirement Document.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"Yes. Amendment 1 expanded the directive by combining two previous ADs and adding repetitive inspections for additional pin locations (forward/aft bottle pins and aft bulkhead fuse pins). Amendment 2 did not expand scope but corrected textual errors in the referenced FAA AD; the effective compliance date was revised to 21 April 1993."},"complexity_factors":["Cross-reference to an external Requirement Document (FAA AD 93-03-14) rather than standalone technical text — requires operators to obtain and follow that AD.","Multiple related service documents referenced (Boeing SBs 747-54-2066 Rev.2, 747-54-2101 Rev.1, ASB 747-54-A2153) increasing document management and traceability needs.","Scope of affected items spans inboard and outboard nacelle struts and several pin locations (forward/aft bottle pins, aft bulkhead fuse pins) — raises inspection planning complexity.","Amendment history: initial issue, Amendment 1 (combined prior ADs and added repetitive inspections), Amendment 2 (textual corrections) — operators must track version-specific compliance dates (revised effective date 21 April 1993).","Operational impact: repetitive inspections impose recurring labour, scheduling and possible downtime costs on operators.","Enforcement mechanism is administrative (CASA directive adopting FAA AD) rather than contractual — discretion for compliance rests with regulator and the technical Requirement Document."],"plain_english_summary":"This directive requires all Boeing 747 operators to carry out inspections and any required corrective action on nacelle strut diagonal brace fuse pins in accordance with FAA AD 93-03-14 as adopted in the Requirement Document, effective 21 April 1993. It responds to in-service cracking reports and changes maintenance obligations. Operators pay for inspections and repairs; CASA mandates compliance. Amendment 1 added repetitive inspections for additional pins, and Amendment 2 corrects textual errors in the FAA document."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment represents a minor technical correction (fixing 'textural errors' from FAA AD 93-01-05) rather than an expansion of scope. The safety requirements and affected aircraft population remain identical to Amendment 1. The original intent — mandating inspection of cracked nacelle strut fuse pins on all Boeing 747 models — has not changed."},"complexity_factors":["Short, single-purpose directive (approximately 250 words)","Only 1 defined term implicitly used ('Applicability')","Heavy reliance on external documents — compliance requires cross-referencing FAA AD 93-03-14 and multiple Boeing Service Bulletins (SB 747-54-2066, SB 747-54-2101, ASB 747-54-A2153)","Contains historical versioning information explaining relationship between Amendment 1, Amendment 2, and superseded FAA directives","Technical aviation terminology requires domain knowledge (nacelle strut, fuse pin, bottle pins, bulkhead)","No nested conditional logic or exceptions within the text itself — complexity is externalized to referenced technical documents"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspections (and replacement if needed) of fuse pins in Boeing 747 nacelle struts after Boeing found cracking that could cause structural failure or engine separation. It requires operators to follow FAA AD 93-03-14 and the referenced Boeing service bulletins.\n\nThis is Amendment 2, correcting text errors in the earlier directive; it applies to all 747s operating in Australian airspace."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-39-amdt-2-nacelle-strut-diagonal-brace-fuse-pin","history":"/api/acts/ad-b747-39-amdt-2-nacelle-strut-diagonal-brace-fuse-pin/history","analysis":"/api/acts/ad-b747-39-amdt-2-nacelle-strut-diagonal-brace-fuse-pin/analysis","conflicts":"/api/acts/ad-b747-39-amdt-2-nacelle-strut-diagonal-brace-fuse-pin/conflicts","importantCases":"/api/acts/ad-b747-39-amdt-2-nacelle-strut-diagonal-brace-fuse-pin/important-cases","documents":"/api/acts/ad-b747-39-amdt-2-nacelle-strut-diagonal-brace-fuse-pin/documents"}}