{"id":"F2006B04683","name":"AD/BELL 47/1 Amdt 1 - Synchronized Elevator Spar","slug":"ad-bell-47-1-amdt-1-synchronized-elevator-spar","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44435,"registerId":"commonwealth-F2006B04683-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 47/1 Amdt 1 - Synchronized Elevator Spar","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)  Bell Helicopter Textron 47 (All Variants) Series Helicopters\n\n \n\nAD/BELL 47/1\n\nAmdt 1\n\n\nSynchronized Elevator Spar 11/76\n\n \n\nApplicability: Model 47J S/Nos. 1420 to 1802. All model 47K. Document:  1. Bell SB No. 135; or\n\n2. FAA AD 76-21-05.\n\n \n\nCompliance: Within 50 hours time in service after 25 November 1976 and thereafter at intervals not exceeding 50 hours time in service.\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 instrument is titled as Amendment 1, but the supplied text does not show any differences from an original AD or otherwise describe a change in scope. Based solely on the provided extract (Applicability; Document; Compliance), there is no shown change to the scope of affected aircraft or to the required inspection intervals."},"complexity_factors":["Narrow applicability to specific models and serial-number range (Model 47J S/N 1420–1802 and all Model 47K). (Applicability)","Mandatory, recurring inspection interval specified (every 50 hours time-in-service). (Compliance)","Procedural details are delegated to external documents (Bell SB No. 135 or FAA AD 76-21-05), requiring operators to obtain and follow those materials. (Document)","Regulatory authority and enforcement fall under the airworthiness directive framework (header), but enforcement procedure and penalties are not set out in the supplied text.","Limited length and narrowly technical focus reduce interpretive complexity but increase operational coordination (scheduling, maintenance resources, parts). (Compliance; Document)"],"plain_english_summary":"### What this instrument does mechanically\n\nThis document is an Airworthiness Directive (AD/BELL 47/1 Amdt 1) that requires scheduled inspections and any corrective action for the synchronized elevator spar on specified Bell 47 helicopters. The directive applies to Model 47J helicopters with serial numbers 1420 through 1802 and to all Model 47K helicopters (see \"Applicability\").\n\nThe AD makes compliance conditional on following one of two external maintenance documents: Bell Service Bulletin No. 135 or FAA AD 76-21-05 (see \"Document\"). It sets the inspection timing at within 50 hours time-in-service after 25 November 1976 and then repeating at intervals not exceeding 50 hours time-in-service (see \"Compliance\").\n\n### Who this affects\n\n- Owners and operators of Bell 47J S/N 1420–1802 and all Bell 47K helicopters. (Applicability)\n- Maintenance organisations and engineers who perform scheduled inspections and repairs according to the referenced Bell or FAA documents. (Document)\n\n### Who pays and who decides\n\n- Costs for inspections, any follow-up repairs or part replacements, and associated aircraft downtime are borne by the owners/operators of the affected helicopters. (Compliance; Applicability)\n- The Civil Aviation Safety Authority has issued the AD under the airworthiness directives schedule (header). The technical means of compliance are prescribed by either Bell SB No. 135 or FAA AD 76-21-05; maintenance providers must carry out the work to meet the AD. (Document)\n\n### Behavioural and operational effects\n\n- Operators must schedule an inspection within the first 50 flight hours after 25 November 1976 and then repeat inspections at intervals not exceeding 50 flight hours. Non‑compliance would leave the aircraft outside the directive’s required maintenance status. (Compliance)\n- The AD delegates the specific inspection and corrective-action procedures to the two referenced documents, so the exact maintenance tasks are performed per those documents rather than within this AD text. (Document)\n\n### Costs, incentives and trade-offs (mechanical description)\n\n- Recurring cost and downtime: the 50‑hour recurring inspection interval creates a recurring maintenance cost and aircraft downtime that operators must absorb. (Compliance)\n- Dependency on external documents: because the AD points to Bell SB No. 135 or FAA AD 76-21-05 for procedures, operators must obtain and follow those documents; this creates a compliance burden of following cross-referenced technical materials. (Document)\n- Choice of remedy: the AD requires compliance with one of two specified documents; it does not within the supplied text prescribe alternative remedies or economic relief, so operators decide which of the two referenced procedures to use and bear the operational consequences. (Document)\n\n### Implementation risk and administrative discretion\n\n- The AD sets a clear, short inspection interval and references external technical guidance. The supplied text does not describe enforcement mechanisms, dispute resolution, or any exemptions; those matters would be handled under the broader regulatory framework. (Header; Compliance)\n\nNotes on source material: the supplied text contains an Applicability clause (models/serial numbers), a Document clause (Bell SB No. 135 or FAA AD 76-21-05), and a Compliance clause (inspect within 50 hours after 25 November 1976 and repeat at intervals not exceeding 50 hours). The supplied extract does not include an explicit statement of the directive’s safety rationale or details of the inspection or corrective actions — those technical details are located in the referenced Bell or FAA documents."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical component on specific helicopter models. As an Airworthiness Directive, it has a narrow, technical scope focused on aviation safety maintenance requirements. There is no indication of scope creep; it remains confined to its original purpose of ensuring airworthiness of the elevator spar assembly."},"complexity_factors":["Extremely short document (approximately 200 words)","Only 2 defined applicability criteria (specific serial number range and model variant)","Simple compliance structure: single time-based trigger (50 hours) with recurring interval","No cross-references to other legislation or regulations beyond citing source documents","No conditional logic, exceptions, or nested provisions","Straightforward command structure: do X by Y, then repeat every Z"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific maintenance or inspections on aircraft.\n\n**What it does:** This AD applies to **Bell 47 series helicopters** (specifically Model 47J with serial numbers 1420–1802, and all Model 47K variants). It mandates **repetitive inspections of the synchronized elevator spar** — a critical flight control component that helps stabilize the helicopter in flight.\n\n**Who must comply:** Owners and operators of the affected Bell 47 helicopters.\n\n**What must be done:**\n- **Initial inspection:** Within 50 hours of flight time after 25 November 1976\n- **Ongoing inspections:** Every 50 hours of flight time thereafter\n\n**Why it matters:** The synchronized elevator spar is essential for safe flight control. This AD was issued to prevent potential structural failures that could lead to loss of control. The reference to \"Bell SB No. 135\" and \"FAA AD 76-21-05\" indicates this addresses a known safety issue identified by the manufacturer and US regulators.\n\n**Key point:** This is **Amendment 1** (Amdt 1), meaning it updates a previous version of this directive."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-47-1-amdt-1-synchronized-elevator-spar","history":"/api/acts/ad-bell-47-1-amdt-1-synchronized-elevator-spar/history","analysis":"/api/acts/ad-bell-47-1-amdt-1-synchronized-elevator-spar/analysis","conflicts":"/api/acts/ad-bell-47-1-amdt-1-synchronized-elevator-spar/conflicts","importantCases":"/api/acts/ad-bell-47-1-amdt-1-synchronized-elevator-spar/important-cases","documents":"/api/acts/ad-bell-47-1-amdt-1-synchronized-elevator-spar/documents"}}