{"id":"F2006B02504","name":"AD/AS 355/5 - Upper Fin Attachment Fitting - Inspection","slug":"ad-as-355-5-upper-fin-attachment-fitting-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41760,"registerId":"commonwealth-F2006B02504-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AS 355/5 - Upper Fin Attachment Fitting - Inspection","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Eurocopter AS 355 (Twin Ecureuil) Series Helicopters\n\n \n\nAD/AS 355/5 Upper Fin Attachment Fitting - Inspection 10/82\n\nApplicability: All model AS 355 not modified in accordance with AMS 350A07.1047 (SB No.\n\n55.02).\n\n \n\nRequirement: Action in accordance with Aerospatiale SB No. 05.03.\n\n \n\nNote: Bureau Veritas AD 82-99-6(B) refers.\n\n \n\nCompliance: Within 10 hours time in service after 1 September 1982 and thereafter at intervals not exceeding 10 hours time in service.\n\n \n\nBackground: Modification in accordance with SB 55.02 provides terminating action for the mandatory repeat inspection.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive applies to all AS 355 helicopters not modified in accordance with AMS 350A07.1047 (SB No. 55.02) and requires repeated inspections at fixed 10-hour intervals, with the SB 55.02 modification serving as terminating action. The text does not expand or narrow that stated applicability beyond the original mechanic of requiring inspections until the terminating modification is fitted (Applicability; Compliance; Background)."},"complexity_factors":["Direct, narrow applicability: only AS 355 models not modified per AMS 350A07.1047 (SB No. 55.02) (Applicability)","Short, explicit compliance prescription: fixed 10-hour inspection interval and initial deadline (Compliance)","Dependence on external technical documents: Aerospatiale SB No. 05.03 (Requirement) and AMS 350A07.1047 / SB No. 55.02 (Background) determine inspection/modification details","Cross-reference to another authority's AD (Bureau Veritas AD 82-99-6(B)) introduces potential for coordination but not additional procedural complexity in this AD (Note)","Operational impact complexity arises from frequent inspection interval (10 hours) affecting scheduling and recurring costs rather than legal or drafting complexity"],"plain_english_summary":"Operators and maintenance organisations of Eurocopter AS 355 helicopters not modified per AMS 350A07.1047 (SB No. 55.02) must inspect the upper fin attachment fitting every 10 hours TIS using Aerospatiale Service Bulletin No. 05.03. The rule addresses an airworthiness concern; installing SB 55.02’s modification terminates the recurring inspections, leaving operators to weigh frequent inspection costs and downtime versus a one‑time modification expense."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted airworthiness directive addressing a specific known defect in a specific aircraft type. It has not expanded beyond its original purpose of ensuring structural integrity of the upper fin attachment fitting."},"complexity_factors":["Single, specific mechanical component addressed (upper fin attachment fitting)","Only one exemption criterion (modification per AMS 350A07.1047 / SB 55.02)","Simple compliance timeline: initial 10 hours, then recurring 10-hour intervals","No nested definitions or interpretation sections","Cross-references limited to two service bulletins and one foreign airworthiness directive (Bureau Veritas AD 82-99-6(B))","Total length: approximately 150 words of substantive content"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\nOrders owners and operators of specific Eurocopter AS 355 helicopters (also called \"Twin Ecureuil\") to inspect a critical part called the **upper fin attachment fitting**. This fitting connects the vertical tail fin to the helicopter's body.\n\n**Who it affects:**\n- All Eurocopter AS 355 model helicopters\n- **Except** those already modified according to a specific service bulletin (AMS 350A07.1047 / SB No. 55.02)\n\n**What must be done:**\n- Follow the inspection procedures in **Aerospatiale Service Bulletin No. 05.03**\n- First inspection: within 10 flight hours after 1 September 1982\n- Repeat inspections: every 10 flight hours thereafter\n\n**Why it matters:**\nThis is a **safety-critical repeat inspection**. The upper fin attachment fitting is structural — if it fails, the tail fin could detach in flight. The directive requires frequent checks until a permanent fix (the modification in SB 55.02) is installed.\n\n**Key point:** The repeated 10-hour inspection cycle stops once the helicopter is modified per SB 55.02 — that modification is the \"terminating action\" that ends the requirement."}},"importantCases":[],"_links":{"self":"/api/acts/ad-as-355-5-upper-fin-attachment-fitting-inspection","history":"/api/acts/ad-as-355-5-upper-fin-attachment-fitting-inspection/history","analysis":"/api/acts/ad-as-355-5-upper-fin-attachment-fitting-inspection/analysis","conflicts":"/api/acts/ad-as-355-5-upper-fin-attachment-fitting-inspection/conflicts","importantCases":"/api/acts/ad-as-355-5-upper-fin-attachment-fitting-inspection/important-cases","documents":"/api/acts/ad-as-355-5-upper-fin-attachment-fitting-inspection/documents"}}