{"id":"F2006B10685","name":"AD/HU 369/21 - Stabiliser Strut Damper Plunger - Inspection and Replacement","slug":"ad-hu-369-21-stabiliser-strut-damper-plunger-inspection-and-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116634,"registerId":"commonwealth-F2006B10685-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HU 369/21 - Stabiliser Strut Damper Plunger - Inspection and Replacement","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)  McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters\n\n \n\nAD/HU 369/21 Stabiliser Strut Damper Plunger - Inspection\n\nand Replacement\n\n\n12/76\n\n \n\nApplicability: All models fitted with P/N 369A2001-601 shock mounted stabiliser strut assembly. Document:               1. Hughes SIN HN-102.1; or\n\n2. FAA AD 76-19-03.\n\n \n\nCompliance: For Part 1 - Within 25 hours time in service after 25 Nov. 1976.\n\n \n\nFor Part 2 (if required) - Within 100 hours time in service after 25 Nov. 1976.\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\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The text lists applicability (all 369-series helicopters fitted with P/N 369A2001-601) and prescribes mandatory inspection and replacement timing tied to 25 November 1976. The instrument itself does not indicate any change in scope from an earlier or original instrument; it simply sets the component scope, the referenced procedural documents, and two compliance time windows. No language in the supplied text asserts an alteration to prior scope."},"complexity_factors":["Narrow applicability limited to helicopters fitted with a single part number (P/N 369A2001-601) reduces scope complexity.","Two-tier compliance timing (Part 1 within 25 hours TIS; Part 2 within 100 hours TIS if required) adds a small scheduling complexity for operators.","Reliance on external technical documents (Hughes SIN HN-102.1 or FAA AD 76-19-03) for procedural details increases operational complexity because the AD does not contain step-by-step inspection/replacement criteria.","Historical absolute reference date (25 November 1976) requires operators to interpret the required TIS windows from that anchor point, which can create practical ambiguity for older records.","Absence of procedural detail in the AD itself forces consultation of service documents, creating administrative steps and potential coordination issues with maintenance providers."],"plain_english_summary":"What this instrument does (mechanical change)\n\n- Requires inspection of the stabiliser strut damper plunger and replacement where indicated for McDonnell Douglas (Hughes) and Kawasaki 369 series helicopters that have the shock-mounted stabiliser strut assembly with part number 369A2001-601. (Applicability)\n- Specifies the technical instructions to follow: Hughes Service Information Notice HN-102.1 or FAA Airworthiness Directive 76-19-03. (Document)\n- Sets mandatory compliance windows measured in hours time-in-service after 25 November 1976: Part 1 inspections must be completed within 25 hours TIS; any follow-up work described in Part 2 must be done within 100 hours TIS if required. (Compliance)\n\nWho is affected\n\n- Owners and operators of all 369-series helicopters fitted with P/N 369A2001-601 stabiliser strut assemblies. They are the parties required to carry out the inspections and any replacements. (Applicability)\n\nWhy it matters (stated purpose and practical implications)\n\n- The document's title and classification indicate its purpose is to ensure the continued airworthiness of the specified component by requiring inspection and replacement where necessary. The instrument implements that purpose by imposing mandatory inspection and replacement obligations and by pointing to detailed procedures in the named technical documents. (title; Document)\n\nCosts, incentives and who decides\n\n- Who pays: the operator/owner must fund the inspection work and any replacement parts and associated labour. (Applicability; Compliance)\n- What is required of operators: schedule the aircraft for inspection within the stated time windows measured in hours time-in-service after 25 November 1976; if the inspection shows replacement is required, arrange and perform that replacement within the specified follow-up interval. (Compliance)\n- What to follow: operators must use the procedures in Hughes SIN HN-102.1 or FAA AD 76-19-03; the AD text itself does not set out the step-by-step procedures but mandates compliance with those documents. (Document)\n\nCompliance burden, discretion and implementation points\n\n- Compliance burden: a short-notice maintenance action measured in TIS (25 hours for Part 1; 100 hours for Part 2 if required) creates scheduling, labour and parts costs and aircraft downtime for affected operators. (Compliance)\n- Discretion: limited. The AD prescribes the component scope, the technical references to use, and the required timing. Operators’ limited choices are when to schedule the work within the given TIS windows and which approved maintenance provider to engage. (Applicability; Document; Compliance)\n- Implementation risk and clarity: the AD relies on external technical documents (Hughes SIN HN-102.1 or FAA AD 76-19-03) for procedural detail; the AD text itself does not record the inspection criteria or replacement thresholds, so an operator must consult those referenced documents to know exactly what to inspect and when replacement is mandatory. (Document)\n\nTrade-offs and opportunity costs\n\n- The instrument imposes immediate maintenance obligations in a narrow, component-specific scope. The direct cost to operators is maintenance labour and parts and short-term aircraft unavailability. The AD centralises the required technical method by pointing to specific service instructions rather than embedding procedures in the AD text itself, transferring the procedural detail to those service documents. (Applicability; Document; Compliance)\n\nKey textual citations\n\n- Applicability: \"All models fitted with P/N 369A2001-601 shock mounted stabiliser strut assembly.\" (Applicability)\n- Documents to follow: \"Hughes SIN HN-102.1; or FAA AD 76-19-03.\" (Document)\n- Compliance windows: \"For Part 1 - Within 25 hours time in service after 25 Nov. 1976. For Part 2 (if required) - Within 100 hours time in service after 25 Nov. 1976.\" (Compliance)\n"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a historical Airworthiness Directive from 1976 with a narrow, specific scope addressing a single known defect in a specific helicopter part. The scope remains tightly focused on the original safety issue without expansion into broader operational or maintenance requirements."},"complexity_factors":["Very short document (approximately 200 words)","Only 1 defined applicability criterion (specific part number P/N 369A2001-601)","Simple two-part compliance structure with clear time-based triggers","No nested exceptions or conditional logic beyond 'if required' for Part 2","References only 2 external technical documents","Single purpose: inspect and replace one specific component"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** issued by Australia's Civil Aviation Safety Authority (CASA) for specific McDonnell Douglas (Hughes) and Kawasaki 369 series helicopters.\n\n**What it does:**\n- Requires owners and operators to inspect and potentially replace a specific part called the **stabiliser strut damper plunger** (part of the helicopter's tail stabiliser system that helps control vibration and movement).\n- The directive applies to all helicopter models fitted with part number **369A2001-601** (a shock-mounted stabiliser strut assembly).\n\n**Who it affects:**\n- Owners and operators of affected Hughes/Kawasaki 369 series helicopters\n- Maintenance organisations servicing these aircraft\n\n**Why it matters:**\n- **Safety critical:** Faulty stabiliser strut dampers can lead to loss of control or structural failure in flight.\n- **Mandatory compliance:** This is not optional advice—it's a legal requirement under the Civil Aviation Regulations 1998. Non-compliance grounds the aircraft (means it cannot legally fly).\n- **Time-sensitive:** The directive sets strict deadlines based on \"time in service\" (flying hours):\n  - **Part 1 (Inspection):** Must be done within 25 flying hours after 25 November 1976\n  - **Part 2 (Replacement, if needed):** Must be done within 100 flying hours after 25 November 1976\n\n**Background:**\nThis directive references technical documents from the manufacturer (Hughes Service Information Notice HN-102.1) and the US Federal Aviation Administration (FAA AD 76-19-03), indicating this addresses a known safety defect discovered in the 1970s."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-369-21-stabiliser-strut-damper-plunger-inspection-and-replacement","history":"/api/acts/ad-hu-369-21-stabiliser-strut-damper-plunger-inspection-and-replacement/history","analysis":"/api/acts/ad-hu-369-21-stabiliser-strut-damper-plunger-inspection-and-replacement/analysis","conflicts":"/api/acts/ad-hu-369-21-stabiliser-strut-damper-plunger-inspection-and-replacement/conflicts","importantCases":"/api/acts/ad-hu-369-21-stabiliser-strut-damper-plunger-inspection-and-replacement/important-cases","documents":"/api/acts/ad-hu-369-21-stabiliser-strut-damper-plunger-inspection-and-replacement/documents"}}