{"id":"F2006B06325","name":"AD/PR/26 Amdt 1 - Front Wall/Snout Radius Cracking","slug":"ad-pr-26-amdt-1-front-wall-snout-radius-cracking","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47479,"registerId":"commonwealth-F2006B06325-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PR/26 Amdt 1 - Front Wall/Snout Radius Cracking","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nPropellers \\- Variable Pitch \\- Dowty Rotol\n\nAD/PR/26\n\nAmdt 1\n\n  \nFront Wall/Snout Radius Cracking 5/90\n\nApplicability: All R212/4-30-4/22, R212/4-30-4/22/1 and R251/4-30-4/49 propellers.\n\nRequirement: Inspect the hub front wall/snout radius area for evidence of cracking in accordance with Dowty Rotol SB 61-1053 Revision 2.\n\nNote: Hubs previously exempt or certified as having complied with AD/PR/20 must be reinspected in accordance with this Directive.\n\nCompliance: In accordance with the Requirement Document.\n\nBackground: Cracks have been found in the front wall/snout radius area in a limited number of hubs modified to VP 2388 standard. The manufacturer now requires all hubs, modified or unmodified, to be inspected and if a hub is found cracked during overhaul a fleet wide recurring inspection is required.\n\nThis Amendment incorporates Revision 2 of the Requirement document.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This Amendment incorporates Revision 2 of the Requirement document (the Dowty Rotol SB 61-1053 Rev 2) and explicitly requires reinspections of hubs that had previously been exempt or certified under AD/PR/20. It also records the manufacturer’s instruction that discovery of a crack at overhaul mandates fleet-wide recurring inspections. These elements broaden the inspection obligation compared with arrangements that allowed prior exemptions and tie compliance to the updated SB. (Requirement; Note; Background; This Amendment)"},"complexity_factors":["Narrow technical scope limited to three specific propeller part numbers (Applicability).","Compliance requires following an external technical document: Dowty Rotol SB 61-1053 Revision 2 (Requirement).","Reinspection requirement for hubs previously exempt under AD/PR/20 introduces an administrative tracking obligation (Note).","A conditional trigger for fleet-wide recurring inspections if a cracked hub is found during overhaul adds potential ongoing compliance obligations (Background).","No multiple exception schemes, offsets, or phased implementation details in the text reduce legal complexity."],"plain_english_summary":"What this instrument does (mechanically)\n\n- Requires operators/maintainers to inspect the hub front wall / snout radius area for cracks on a specified set of Dowty Rotol propellers: R212/4-30-4/22, R212/4-30-4/22/1 and R251/4-30-4/49. (Applicability; Requirement)\n- The inspection must be carried out in accordance with Dowty Rotol Service Bulletin (SB) 61-1053 Revision 2. (Requirement)\n- Hubs that were previously exempt or certified as compliant under AD/PR/20 must be reinspected under this Directive. (Note)\n- If a crack is discovered in a hub during overhaul, the manufacturer requires a fleet-wide recurring inspection to follow. (Background)\n- Compliance is to be carried out in accordance with the referenced Requirement Document (the SB). (Compliance)\n\nStated reason and the source's claim\n\n- The Directive records that cracks were found in the front wall/snout radius area on a limited number of hubs that had been modified to VP 2388 standard, and notes the manufacturer’s position that all hubs (modified or not) should be inspected; it also records that a crack found at overhaul triggers a fleet-wide recurring inspection. (Background)\n\nWho pays, who decides, and what changes in behaviour\n\n- Who pays: Aircraft owners/operators and their maintenance providers bear the direct costs of carrying out the inspections, any additional recurring inspections triggered by a crack, and any repair or replacement work required. (Requirement; Note; Background)\n- Who decides: The Civil Aviation Safety Authority issues the Directive; the exact inspection steps and intervals are determined by the Dowty Rotol SB 61-1053 Revision 2 (the Requirement Document). Operators must follow that document to be compliant. (Requirement; Compliance)\n- Behaviour change required: Maintenance organisations must inspect the specified hubs according to the SB, re-inspect hubs previously exempt under AD/PR/20, and, where a cracked hub is found during overhaul, implement fleet-wide recurring inspections as required by the manufacturer. (Requirement; Note; Background)\n\nImplementation, compliance burden and risks (mechanical and administrative)\n\n- Compliance burden: Inspections must be performed to the procedures in SB 61-1053 Rev 2. That creates a procedural dependency on an external service bulletin for technical detail and compliance timing. (Requirement)\n- Administrative burden: Operators must track which hubs were previously exempt under AD/PR/20 and ensure those hubs are reinspected. (Note)\n- Recurring workload: Discovery of a crack during overhaul triggers fleet-wide recurring inspections, increasing ongoing maintenance workload and potential aircraft downtime for the fleet. (Background)\n- Implementation risk: The effectiveness of this Directive depends on inspection quality and the SB’s detection capability; missed or improper inspections could leave cracked hubs in service. (Requirement; Background)\n\nIncentives, trade-offs and concrete effects on private choices and markets\n\n- Incentives: The Directive incentivises operators to inspect and, where necessary, remove or repair cracked hubs to avoid in-service failures. (Requirement; Background)\n- Trade-offs and opportunity costs: Time and labour spent on inspections and recurring inspections divert maintenance resources and may cause aircraft downtime. Operators must weigh inspection/repair costs against keeping aircraft available. (Requirement; Background)\n- Market effects: Demand for maintenance hours, inspection services and replacement hubs or repairs will increase for operators of the specified propellers; the Directive relies on the manufacturer's SB as the technical standard for compliance. (Requirement)\n\nConcentrated benefits and diffuse costs (mechanical mechanism, not judgment)\n\n- Concrete benefit: Identifies and removes cracked hubs from service to address the specific defect reported by the manufacturer (Background).\n- Costs: The costs of inspection and any necessary repairs are borne by operators and maintenance providers, spread across those who operate the listed propeller types. (Requirement; Note; Background)\n\nReference points in the instrument\n\n- Applicability: lists the exact propeller models covered. (Applicability)\n- Requirement: mandates inspection to Dowty Rotol SB 61-1053 Revision 2. (Requirement)\n- Note: requires reinspecting hubs previously exempt or certified under AD/PR/20. (Note)\n- Background: explains how cracks were found in some VP 2388–modified hubs and the manufacturer’s fleet-wide recurring inspection trigger. (Background)\n- Amendment: this version incorporates Revision 2 of the Requirement document (the SB). (This Amendment)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard amendment to an existing Airworthiness Directive. The original AD addressed cracking in modified hubs; this amendment simply incorporates the manufacturer's updated service bulletin (Revision 2) and clarifies that previously exempted hubs must now be inspected. The scope remains tightly focused on the specific safety issue (hub cracking) and has not expanded beyond aviation safety maintenance requirements."},"complexity_factors":["Single, specific mechanical component targeted (propeller hub)","Only 3 specific propeller model numbers affected","Single inspection requirement with reference to external manufacturer document","One conditional trigger (crack found during overhaul → recurring inspections required)","No nested definitions, no interpretive provisions, no cross-references to other legislation beyond the parent Civil Aviation Regulations","Total length: approximately 200 words"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's aviation regulator (CASA) that requires aircraft owners and operators to take specific action to fix a known safety problem.\n\n**What it does:**\nOrders inspections of specific Dowty Rotol propeller hubs (models R212/4-30-4/22, R212/4-30-4/22/1, and R251/4-30-4/49) to check for cracks in the \"front wall/snout radius\" — a curved structural area where the propeller attaches to the aircraft engine.\n\n**Who it affects:**\nAnyone who owns, operates, or maintains aircraft fitted with these specific propeller models. This includes airlines, charter operators, flying schools, and private aircraft owners.\n\n**What must be done:**\n- Inspect the propeller hub following the manufacturer's service bulletin (SB 61-1053 Revision 2)\n- Even if a propeller was previously checked under an older directive (AD/PR/20) or had an exemption, it must be reinspected under this new order\n- If cracks are found during an overhaul, the entire fleet of these propellers must undergo repeated (recurring) inspections\n\n**Why it matters:**\nCracks in propeller hubs can lead to catastrophic failure — the propeller could detach from the engine in flight. This directive was issued after cracks were discovered in some modified hubs, and the manufacturer expanded the safety check to cover all hubs regardless of modification status. This amendment updates the inspection requirements to the latest manufacturer standards (Revision 2)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pr-26-amdt-1-front-wall-snout-radius-cracking","history":"/api/acts/ad-pr-26-amdt-1-front-wall-snout-radius-cracking/history","analysis":"/api/acts/ad-pr-26-amdt-1-front-wall-snout-radius-cracking/analysis","conflicts":"/api/acts/ad-pr-26-amdt-1-front-wall-snout-radius-cracking/conflicts","importantCases":"/api/acts/ad-pr-26-amdt-1-front-wall-snout-radius-cracking/important-cases","documents":"/api/acts/ad-pr-26-amdt-1-front-wall-snout-radius-cracking/documents"}}