{"id":"F2006B06323","name":"AD/PR/24 Amdt 6 - Beta Tube","slug":"ad-pr-24-amdt-6-beta-tube","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47472,"registerId":"commonwealth-F2006B06323-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PR/24 Amdt 6 - Beta Tube","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 - 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Propellers - Variable Pitch - Dowty Rotol\n\n \n\nAD/PR/24\n\nAmdt 6\n\n\nBeta Tube 2/90\n\n \n\nApplicability: All models R354/4-123-F/13 R354/4-123-F/20 and R375/4-123-F/21.\n\n \n\nRequirement: Action in accordance with Dowty Rotol Mandatory Service Bulletin 61-A1021 Revision 10.\n\n \n\nNote: Swedish AD SAD No 1-007 refers.\n\n \n\nCompliance: In accordance with the Requirement document.\n\n \n\nBackground: The manufacturer has further increased the service life of specific part number beta tubes and added additional propeller models to the applicability lists.\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":true,"description":"The AD updates scope compared with prior material by (1) increasing the approved service life of specific beta‑tube part numbers and (2) adding additional propeller models to the applicability list. These changes are stated in the Background: \"The manufacturer has further increased the service life of specific part number beta tubes and added additional propeller models to the applicability lists.\" (Background). Mechanically, the AD enforces the manufacturer’s Revision 10 of Mandatory Service Bulletin 61‑A1021 for the newly included models and revised life limits (Requirement; Compliance). The practical effects are a reduction in replacement frequency for the affected part numbers and a larger set of operators required to follow the mandatory bulletin."},"complexity_factors":["Mandates compliance with an external technical document (Dowty Rotol Mandatory Service Bulletin 61‑A1021 Revision 10) rather than specifying tasks in the AD itself (Requirement; Compliance).","Technical subject matter (propeller beta tubes) requires specialised maintenance skills and part identification (Applicability; Background).","Applicability limited to specific model numbers, so operators must correctly identify affected equipment (Applicability).","Change in service life and added models affects maintenance scheduling and parts demand, introducing operational planning complexity (Background).","Cross‑reference to foreign ADs (Swedish AD) may require operators to check related documents for context (Note)."],"plain_english_summary":"### What this directive does\n\nThis Airworthiness Directive (AD/PR/24 Amdt 6 — “Beta Tube 2/90”) requires operators of certain Dowty Rotol variable‑pitch propellers to carry out the actions set out in the manufacturer’s mandatory service bulletin. The formal obligation is: “Action in accordance with Dowty Rotol Mandatory Service Bulletin 61‑A1021 Revision 10.” (Requirement).\n\nWho it affects\n\n- Owners and operators of propellers listed under “Applicability”: all models R354/4‑123‑F/13, R354/4‑123‑F/20 and R375/4‑123‑F/21. (Applicability)\n- Maintenance organisations and technicians who perform work on these propellers because they must follow the specified service bulletin.\n\nHow it works mechanically\n\n- The regulator makes compliance with the manufacturer’s Mandatory Service Bulletin 61‑A1021 Revision 10 compulsory. (Requirement; Compliance)\n- Operators must apply whatever inspections, life‑limits, repairs or replacements the service bulletin prescribes; the AD does not restate those technical steps, it mandates following the bulletin exactly. (Requirement; Compliance)\n\nStated reason and what changed\n\n- The manufacturer reports two concrete changes: it has increased the service life for specific beta‑tube part numbers and it has added additional propeller models to the list of affected types. That explanation appears in the AD’s Background. (Background)\n- The AD also cross‑references a Swedish AD (Note), indicating related regulatory action elsewhere.\n\nWho pays, who decides, and how behaviour changes\n\n- Who pays: operators bear the direct costs (inspection time, labour, parts and any downtime) required by the service bulletin. Maintenance providers incur labour costs to perform the work. Parts suppliers may see changed demand because of altered service lives. (Requirement; Background)\n- Who decides: the Civil Aviation safety regulator enforces the AD; the manufacturer defines the technical work by issuing Mandatory Service Bulletin 61‑A1021 Revision 10. The AD ties regulatory compliance to that bulletin. (Requirement; Compliance)\n- Behaviour change: operators must identify affected propellers, schedule and perform the bulletin’s tasks, and keep records to show compliance. They cannot substitute alternative procedures unless those are accepted under the regulatory system.\n\nCosts, incentives and trade‑offs to note (source‑grounded)\n\n- Reduced replacement frequency: increasing the service life of certain beta‑tube part numbers (Background) tends to lower recurring parts and replacement costs for owners of those parts, but requires regulator adoption through the AD for legal acceptability. (Background)\n- Increased coverage: adding models to the applicability list (Background) increases the number of operators required to comply and therefore increases aggregate compliance costs. (Background)\n- Reliance on an external document: the AD mandates an external technical document (the service bulletin). Operators must obtain and interpret that bulletin; the AD does not reproduce its content, so the precise compliance burden depends on the bulletin’s technical requirements. (Requirement; Compliance)\n- Market effects: changing service lives alters demand for replacement beta tubes and related maintenance services. This benefits operators who keep parts in service longer and shifts maintenance workload among providers; the AD itself does not direct which providers may perform the work beyond the usual regulatory requirements. (Background; Requirement)\n- Implementation risk and administrative burden: effective compliance depends on accurate identification of affected part numbers and propeller models, access to the correct Service Bulletin Revision 10, availability of parts and qualified maintenance staff, and record‑keeping to demonstrate compliance. (Applicability; Requirement; Compliance)\n\nPractical takeaway\n\n- If you operate one of the listed propeller models, you must follow Dowty Rotol Mandatory Service Bulletin 61‑A1021 Revision 10 for the actions it prescribes. The manufacturer’s changes (longer service life for some parts and more models included) are the reason for this AD; the exact work and scheduling come from the service bulletin itself. (Applicability; Requirement; Background; Compliance)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is Amendment 6 to an existing Airworthiness Directive. The Background explicitly states this amendment simply extends service life for specific part numbers and adds additional propeller models to applicability lists. This represents incremental technical updating consistent with the original purpose — maintaining airworthiness of Dowty Rotol propellers — rather than scope creep."},"complexity_factors":["Extremely short document (approximately 150 words of substantive content)","Only 3 defined propeller model numbers in applicability section","Single operative requirement that cross-references an external document (the Service Bulletin) rather than setting out detailed technical steps","No nested exceptions, conditional logic, or interpretative provisions","Standardised AD format with boilerplate sections (Applicability, Requirement, Compliance, Background)","No internal cross-references to other legislation or regulations"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** issued by Australia's Civil Aviation Safety Authority (CASA). It mandates safety maintenance on specific **Dowty Rotol variable-pitch propellers** used on aircraft.\n\n**What it does:**\n- Requires owners and operators of certain propeller models (R354/4-123-F/13, R354/4-123-F/20, and R375/4-123-F/21) to follow a specific maintenance procedure\n- The procedure is detailed in **Dowty Rotol Mandatory Service Bulletin 61-A1021 Revision 10** — essentially, the manufacturer has updated how long certain \"beta tubes\" (a component that controls propeller pitch/angle) can safely remain in service\n\n**Who it affects:**\n- Aircraft operators and maintenance organisations using these specific Dowty Rotol propeller models\n- Anyone responsible for the airworthiness (safety certification) of aircraft fitted with these propellers\n\n**Why it matters:**\n- **Safety critical:** Beta tubes are essential components; if they fail, pilots may lose control of propeller pitch, potentially causing loss of thrust or control\n- The manufacturer has **extended service life limits** for some parts and **added more propeller models** to the safety program — meaning more aircraft are now covered, and some parts can stay in service longer than previously thought (or must be replaced sooner if they don't meet the new criteria)\n- Non-compliance means the aircraft is not legally airworthy and cannot fly\n\n**Key terms explained:**\n- **Airworthiness Directive (AD):** A legally binding safety order from the aviation regulator\n- **Beta tube:** A hydraulic component in variable-pitch propellers that controls the blade angle (\"beta angle\")\n- **Mandatory Service Bulletin:** Manufacturer's instructions that become compulsory when referenced in an AD"}},"importantCases":[],"_links":{"self":"/api/acts/ad-pr-24-amdt-6-beta-tube","history":"/api/acts/ad-pr-24-amdt-6-beta-tube/history","analysis":"/api/acts/ad-pr-24-amdt-6-beta-tube/analysis","conflicts":"/api/acts/ad-pr-24-amdt-6-beta-tube/conflicts","importantCases":"/api/acts/ad-pr-24-amdt-6-beta-tube/important-cases","documents":"/api/acts/ad-pr-24-amdt-6-beta-tube/documents"}}