{"id":"F2006B06124","name":"AD/PC-6/21 - Control System Inspection and Modification","slug":"ad-pc-6-21-control-system-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":46893,"registerId":"commonwealth-F2006B06124-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PC-6/21 - Control System Inspection and Modification","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)  Pilatus Porter PC-6 Series Aeroplanes\n\n \n\n \n\n| AD/PC-6/21 | Control System Inspection and Modification | 11/67 |\n| --- | --- | --- |\n| Applicability: | All models. |  |\n| Document: | Pilatus SB No. 74. |  |\n\n\n \n\nCompliance: Inspect at intervals not exceeding 100 hours time in service until modified - modify before 1 April 1968.\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\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive's scope, as stated in the document provided, covers all Pilatus PC-6 models, requires inspections every 100 hours until modification, and mandates modification by 1 April 1968 with technical detail in Pilatus SB No. 74 (Applicability; Compliance; Document). Nothing in the text indicates an alteration of that scope from its stated requirements."},"complexity_factors":["Single, simple recurring action: inspect at intervals not exceeding 100 hours time in service (Compliance).","Single mandated outcome: complete modification by a fixed calendar date (Compliance).","Narrow applicability: applies to all Pilatus PC-6 models only (Applicability).","Technical execution delegated to a single referenced service bulletin (Pilatus SB No. 74) which contains the procedural detail (Document).","Administrative enforcement under an identified regulatory provision (Civil Aviation Regulations, Part 39) but no layered procedural requirements in the text (header)."],"plain_english_summary":"This directive requires owners/operators of Pilatus PC‑6 aeroplanes to inspect the flight‑control system every ≤100 hours TIS until completing a mandatory modification per Pilatus Service Bulletin No. 74, to be carried out by 1 April 1968. The Civil Aviation Safety Authority enforces compliance; owners/operators bear inspection, repair and modification costs. It’s aimed at ensuring control‑system integrity but creates recurring inspection burdens, scheduling pressure and potential maintenance bottlenecks before the deadline."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive from 1967 (indicated by the '11/67' reference, likely November 1967). It addresses a specific technical issue with control systems on a single aircraft type. There is no evidence of scope creep; it remains tightly focused on its original purpose of mandating inspection and modification per the manufacturer's service bulletin."},"complexity_factors":["Extremely short document (under 200 words)","Only 2 substantive requirements (inspection interval + modification deadline)","Single defined reference (Pilatus SB No. 74 — the manufacturer's service bulletin)","No nested exceptions, conditional logic, or cross-references to other legislation","Clear applicability statement ('All models') with no exclusions","Simple temporal compliance structure (recurring interval + hard deadline)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order — issued by Australia's Civil Aviation Safety Authority (CASA) for **Pilatus Porter PC-6 series aeroplanes** (a type of small utility aircraft).\n\n**What it requires:**\n- **Inspection:** Aircraft owners/operators must inspect the control systems every **100 hours of flight time** (\"time in service\" means actual flying hours, not just engine running time).\n- **Modification:** They must also carry out a specific modification to the control systems **before 1 April 1968**.\n\n**Why it matters:**\nControl systems are what allow pilots to steer the aircraft (think: ailerons, elevators, rudder). A failure here means loss of control and likely a crash. This AD was issued because Pilatus (the manufacturer) identified a safety issue in their Service Bulletin No. 74, and CASA made compliance mandatory.\n\n**Who it affects:**\nAnyone operating a Pilatus PC-6 in Australia — whether private owners, charter companies, or government operators. Non-compliance means the aircraft cannot legally fly.\n\n**Key point:** This is a **time-limited safety fix** — you keep inspecting regularly until you do the permanent modification, and you absolutely must do that modification by the April 1968 deadline."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pc-6-21-control-system-inspection-and-modification","history":"/api/acts/ad-pc-6-21-control-system-inspection-and-modification/history","analysis":"/api/acts/ad-pc-6-21-control-system-inspection-and-modification/analysis","conflicts":"/api/acts/ad-pc-6-21-control-system-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-pc-6-21-control-system-inspection-and-modification/important-cases","documents":"/api/acts/ad-pc-6-21-control-system-inspection-and-modification/documents"}}