{"id":"F2006B06319","name":"AD/PR/20 - Hub Front Face to Snout Radius - Inspection","slug":"ad-pr-20-hub-front-face-to-snout-radius-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47459,"registerId":"commonwealth-F2006B06319-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PR/20 - Hub Front Face to Snout Radius - 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 - 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/20 Hub Front Face to Snout Radius - Inspection NK\n\nApplicability: All model (c) R175/4-30-4/13E, (c) R186/4-30-4/16 and 16/1, (c) R212/4-30-4/22/1 propellers not modified in accordance with Mod. VP 2388.\n\n \n\nRequirement: In accordance with an approved eddy current technique, inspect the hub front face to dome mount radius for cracking.\n\n \n\nCompliance: For all propellers which have not been modified in accordance with Mod. VP 2388 - inspect in accordance with the requirement within 1500 hours time in service after 30 September 1978, and thereafter at intervals not exceeding 1500 hours.\n\n \n\nNote: NAC Eddy Current Technique TB-61-10 F3201 NAC9 is an approved technique.\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":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This appears to be a discrete, targeted safety directive focused on a specific mechanical defect in specific propeller models. There is no indication of scope creep; it maintains its original narrow purpose of mandating inspections for crack detection in a defined population of aircraft components."},"complexity_factors":["Single, specific technical requirement (one inspection task)","Limited applicability (4 specific propeller models, with one modification exemption)","Simple compliance structure (one-time initial deadline + recurring interval)","No cross-references to other legislation or regulations","No defined terms section","Single exception (modified propellers per Mod. VP 2388)","Document appears to be a standalone directive, not embedded in complex regulatory framework in this extract"],"plain_english_summary":"This is a **safety inspection rule** (called an \"Airworthiness Directive\") issued by Australia's Civil Aviation Safety Authority. It applies to specific models of **Dowty Rotol variable-pitch aircraft propellers**.\n\n**What it requires:**\n- Aircraft owners or operators must **inspect a specific part of the propeller hub** — the curved area where the front face meets the dome mount — for **cracks**.\n- The inspection must use a special **eddy current technique** (a non-destructive testing method using electromagnetic fields to detect surface cracks).\n\n**Who must comply:**\n- Anyone operating aircraft with these specific propeller models: **R175/4-30-4/13E, R186/4-30-4/16, R186/4-30-4/16/1, or R212/4-30-4/22/1** — **unless** the propeller has already been modified according to \"Mod. VP 2388\".\n\n**When to do it:**\n- First inspection: within **1,500 flight hours** after 30 September 1978.\n- Repeat inspections: **every 1,500 flight hours** thereafter.\n\n**Why it matters:**\nCracks in propeller hubs can lead to **catastrophic failure** in flight. This rule prevents accidents by mandating regular checks of a known weak point in these specific propeller designs.\n\n**Approved method:**\nThe directive notes that \"NAC Eddy Current Technique TB-61-10 F3201 NAC9\" is an approved inspection method."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope is confined to the listed propeller models not modified by Mod. VP 2388 and prescribes a specific inspection method and interval. The text contains no express indication that the applicability or inspection requirement has been broadened or narrowed from any prior version; the Mod. VP 2388 exemption provides an alternate status for modified units (Applicability)."},"complexity_factors":["Technical specificity: requires a non‑destructive eddy‑current inspection of a small propeller radius (Requirement).","Limited applicability: applies only to certain Dowty Rotol models and excludes propellers modified by Mod. VP 2388 (Applicability).","Recurring compliance tracking: set initial and repeating intervals of 1,500 hours time in service (Compliance).","Reference to an approved technique: names NAC Eddy Current Technique TB-61-10 F3201 NAC9 as approved (Note), creating dependency on that documented method.","Operational burden: inspection requires specialised tooling/skills and scheduled downtime for affected aircraft (implied by Requirement and Compliance)."],"plain_english_summary":"This airworthiness directive requires operators of specified Dowty Rotol variable-pitch propellers (models listed) to have the hub front-face to dome-mount radius inspected for cracking using an approved eddy‑current method, unless the propeller has been modified by Mod. VP 2388. Inspections must be done within 1,500 flight hours after 30 September 1978 and then every 1,500 hours. The inspection duty and costs fall on the aircraft operator/owner; the regulator sets the requirement and approved techniques dictate how work is performed."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pr-20-hub-front-face-to-snout-radius-inspection","history":"/api/acts/ad-pr-20-hub-front-face-to-snout-radius-inspection/history","analysis":"/api/acts/ad-pr-20-hub-front-face-to-snout-radius-inspection/analysis","conflicts":"/api/acts/ad-pr-20-hub-front-face-to-snout-radius-inspection/conflicts","importantCases":"/api/acts/ad-pr-20-hub-front-face-to-snout-radius-inspection/important-cases","documents":"/api/acts/ad-pr-20-hub-front-face-to-snout-radius-inspection/documents"}}