{"id":"F2006B03108","name":"AD/B747/209 - Nacelle Strut Fuse Pins","slug":"ad-b747-209-nacelle-strut-fuse-pins","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42480,"registerId":"commonwealth-F2006B03108-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/209 - Nacelle Strut Fuse Pins","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/B747/209 Nacelle Strut Fuse Pins 8/99\n\nApplicability: Model 747-200, and \\-300 series aircraft equipped with General Electric Model CF6- 80C2 series engines, and Model 747-400 series aircraft; as listed in Boeing Service Bulletin 747-54-2155 Revision 2; except those aircraft on which modification of the strut/wing structure have been accomplished in accordance with either FAA AD 95- 13-05 or AD 95-13-06.\n\nRequirement: Action in accordance with the technical requirements of FAA AD 99-10-10 Amdt 39- 11163.\n\nCompliance: As specified in the Requirement Document with a revised effective date of 12 August 1999.\n\nThis Airworthiness Directive becomes effective on 12 August 1999.\n\nBackground: The FAA received reports of cracked fuse pins in the upper link, midspar fittings, and diagonal brace of the nacelle strut due to fatigue and corrosion. Cracks or corrosion of the fuse pins could result in failure of the fuse pin and strut-to-wing attachment.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive implementing a specific safety requirement. It matches its original purpose exactly: addressing a known mechanical defect in specific aircraft through mandatory inspection/repair. No scope creep is evident."},"complexity_factors":["Very short document (under 200 words)","Only 4 defined applicability criteria (aircraft models, engine type, service bulletin reference, exemptions)","Single requirement: comply with external FAA directive","No nested conditions or exceptions beyond the single exemption clause","No internal cross-references to other sections of Australian regulations","Straightforward compliance date structure"],"plain_english_summary":"This is a **safety order for specific Boeing 747 aircraft** that requires airlines to inspect and fix a dangerous mechanical problem.\n\n**What it does:**\n- Orders checks and repairs on **fuse pins** — special safety bolts that connect the engine housing (nacelle strut) to the aircraft's wing\n- These pins are designed to break away in emergencies, but cracks from **metal fatigue and rust** could cause them to fail unexpectedly\n\n**Who it affects:**\n- **Boeing 747-200, 747-300, and 747-400 aircraft** with General Electric CF6-80C2 engines\n- Specifically those listed in Boeing Service Bulletin 747-54-2155 Revision 2\n- **Exempt:** Aircraft already modified under two earlier US safety orders (FAA AD 95-13-05 or 95-13-06)\n\n**What airlines must do:**\n- Follow the technical instructions in **FAA AD 99-10-10** (a US aviation safety order)\n- Complete the work by the deadlines set in that document, counting from **12 August 1999**\n\n**Why it matters:**\nFailed fuse pins could cause the **engine strut to detach from the wing** — a catastrophic failure that could lead to loss of the aircraft. The FAA discovered this problem after receiving reports of cracked pins, prompting this urgent safety action."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Scope remains focused on inspection and corrective action for nacelle strut fuse pins on the listed 747 variants, adopting FAA AD 99‑10‑10 and excluding aircraft already modified per FAA AD 95‑13‑05 or 95‑13‑06 (Applicability; Requirement; Background)."},"complexity_factors":["Direct incorporation of a foreign regulator's directive (FAA AD 99‑10‑10) creates dependency on external technical requirements and revisions (Requirement).","Applicability is limited to specific airframe models and engine type, requiring operators to check model lists in Boeing Service Bulletin 747‑54‑2155 Revision 2 (Applicability).","Exclusions for aircraft modified under FAA AD 95‑13‑05 or 95‑13‑06 add an eligibility/record‑checking step for operators and maintainers (Applicability).","Safety‑critical inspections and potential repairs of structural fuse pins impose operational and maintenance burden on affected operators (Background; Requirement).","Fixed compliance date (effective 12 August 1999) creates a clear timeline for action but requires programme scheduling and parts/technical support (Compliance)."],"plain_english_summary":"This Airworthiness Directive requires operators of specified Boeing 747‑200/‑300 (with GE CF6‑80C2 engines) and 747‑400 aeroplanes to carry out the inspections and corrective actions set out in FAA AD 99‑10‑10, as referenced in Boeing Service Bulletin 747‑54‑2155 Revision 2, excluding aircraft already modified under FAA AD 95‑13‑05 or 95‑13‑06 (Applicability; Requirement; Compliance). It responds to reports of cracked or corroded nacelle strut fuse pins that could allow strut‑to‑wing attachment failure (Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-209-nacelle-strut-fuse-pins","history":"/api/acts/ad-b747-209-nacelle-strut-fuse-pins/history","analysis":"/api/acts/ad-b747-209-nacelle-strut-fuse-pins/analysis","conflicts":"/api/acts/ad-b747-209-nacelle-strut-fuse-pins/conflicts","importantCases":"/api/acts/ad-b747-209-nacelle-strut-fuse-pins/important-cases","documents":"/api/acts/ad-b747-209-nacelle-strut-fuse-pins/documents"}}