{"id":"F2006B08404","name":"AD/CESSNA 500/4 Amdt 1 - Flight Compartment Side Windows - Inspection and Replacement","slug":"ad-cessna-500-4-amdt-1-flight-compartment-side-windows-inspection-and-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115857,"registerId":"commonwealth-F2006B08404-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 500/4 Amdt 1 - Flight Compartment Side Windows - Inspection and Replacement","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)  Cessna 500 (Citation) Series Aeroplanes\n\n \n\nAD/CESSNA 500/4\n\nAmdt 1\n\n\nFlight Compartment Side Windows - Inspection and Replacement\n\n\n11/74\n\n \n\nApplicability: All model 500 except those fitted with flight compartment side windows P/Nos. 5511285-34-4.\n\n \n\nRequirement: 1. Inspect in accordance with Cessna Citation SL 56-2 Rev. 1.\n\n \n\n2. Replace in accordance with SB 56-4.\n\n \n\nCompliance: Before achieving 400 hours time in service and thereafter at intervals not exceeding 100 hours time in service until modified.\n\n \n\nModify before 1 September 1975.\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 supplied amendment text sets applicability, inspection and replacement requirements, and a compliance schedule. The document is identified as an amendment (Amdt 1) but the supplied text does not state how these requirements differ from the prior version or the original intent. Based solely on the provided text, there is no explicit indication that the scope (which aircraft are covered or what actions are required) has changed from the original intent; the AD simply prescribes the stated inspection/replacement regime and a modification deadline."},"complexity_factors":["Clear, narrow applicability (single aircraft model with a single part-number exception) reduces scope complexity (Applicability).","Prescriptive, limited set of actions (inspect per SL 56-2 Rev. 1; replace per SB 56-4) keeps procedural complexity low (Requirement).","Recurring inspection interval (initial <400 hours, then ≤100 hours) creates operational scheduling complexity for operators (Compliance).","Dependency on external manufacturer documents (SL 56-2 Rev. 1 and SB 56-4) adds interpretation and access complexity.","A fixed calendar modification deadline (Modify before 1 September 1975) imposes a time-pressure constraint that can complicate planning.","Technical implementation requires qualified maintenance personnel and parts supply, adding practical complexity not explained in the text."],"plain_english_summary":"What this directive does (mechanical effect):\n\n- Applies to: All Cessna 500 (Citation) aeroplanes except those already fitted with flight compartment side windows part number 5511285-34-4. (Applicability)\n- Requires two actions: (1) inspect the flight compartment side windows in accordance with Cessna Citation SL 56-2 Rev. 1; and (2) replace the windows in accordance with Service Bulletin (SB) 56-4. (Requirement)\n- Sets timing: initial inspection must occur before the aeroplane accrues 400 hours time in service, and thereafter inspections must repeat at intervals not exceeding 100 hours time in service until the aircraft is ‘‘modified.’’ A final modification deadline is stated as \"Modify before 1 September 1975.\" (Compliance / Modify before date)\n\nStated purpose and what the text itself allows you to infer:\n\n- The text does not set out an explicit policy rationale beyond the inspection and replacement instructions themselves. The directive prescribes inspections and replacement steps by reference to the manufacturer’s documents (SL 56-2 Rev. 1 and SB 56-4). (Requirement)\n\nWho pays and who decides:\n\n- Aircraft owners/operators pay for the inspections, any replacements, and any associated downtime and labour because the directive obliges the operator to have the inspections and replacements completed. (Compliance)\n- The technical decisions about how to carry out inspections and replacements are delegated to maintenance personnel following the referenced Cessna documents (SL 56-2 Rev. 1 and SB 56-4). The AD is prescriptive about what documents must be followed, but not about exact shop-level methods beyond those documents. (Requirement)\n\nIncentives, trade-offs and practical effects (mechanisms, not judgments):\n\n- Exclusion by part number (5511285-34-4) creates a clear incentive for operators to fit that part if doing so legally and practically removes the AD’s recurring inspection obligation for that fleet subset. (Applicability)\n- Operators who do not have that P/N must budget for recurring inspections (initial before 400 hours, then every 100 hours) and potential replacements until the modification is completed. The recurring interval creates ongoing operating cost and maintenance scheduling impacts. (Compliance)\n- The directive relies on external Cessna documents for technical method. That creates a dependency: compliance requires access to and adherence to those manufacturer materials (administrative/transactional cost). (Requirement)\n- The directive sets a firm calendar modification deadline (\"Modify before 1 September 1975\"). That introduces a time-compliance constraint that could force earlier-than-planned maintenance or procurement of parts. (Modify before date)\n\nCompliance burden, implementation risk and discretion:\n\n- Compliance burden: periodic inspections every 100 hours until modification, plus replacement costs if SB 56-4 specifies parts or procedures that require parts/labour. The frequency (100 hours) is operationally meaningful for scheduling and costs. (Compliance)\n- Implementation risk: carrying out the inspections and replacements requires qualified maintenance personnel and availability of parts referenced in the service bulletin. If parts or qualified labour are constrained, aircraft may be grounded or operators may incur delays. (Requirement / SB reference)\n- Bureaucratic discretion: the AD is prescriptive; the text does not provide discretionary exemptions or alternative compliance paths in the directive itself. Any alternative method would therefore need separate approval under the regulatory framework (not described in the supplied text). (Overall)\n\nNet effect on private choice and market activity:\n\n- The directive shifts costs and scheduling choices to aircraft operators and maintenance providers. Operators must choose whether to fit the exempting part (if available) or to accept the ongoing inspection/replacement schedule until they comply with the modification requirement. Maintenance organisations gain predictable work from inspections and replacements, subject to demand.\n\nSource citations: statements above cite the text lines labeled \"Applicability\", \"Requirement\", \"Compliance\" and the deadline line \"Modify before 1 September 1975\" from the supplied AD (AD/CESSNA 500/4 Amdt 1)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is Amendment 1 to an existing Airworthiness Directive. The scope remains tightly focused on the original safety issue: Cessna 500 series flight compartment side windows. The amendment appears to update technical references or compliance details without expanding beyond the original aircraft model and defect scope."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 2 defined references to external technical documents (Cessna SL 56-2 Rev. 1 and SB 56-4)","Simple conditional applicability (one exclusion based on part number)","Straightforward compliance timeline with two clear triggers (hours-based and calendar-based)","No nested exceptions, cross-references to other legislation, or conditional logic beyond the single exemption"],"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). Think of it as a \"recall notice\" for aircraft, but legally binding.\n\n**What it does:** It requires owners and operators of **Cessna 500 series aircraft** (also known as Citation jets) to inspect and replace the **flight compartment side windows** (the pilot's side windows) on a strict schedule to prevent failures that could endanger flight safety.\n\n**Who it affects:**\n- **All Cessna Model 500 aircraft** — *except* those already fitted with specific replacement windows (part number 5511285-34-4)\n- Aircraft owners, operators, and maintenance organisations responsible for these planes\n\n**What must be done:**\n1. **Inspect** the windows following Cessna's Service Letter 56-2 (Revision 1)\n2. **Replace** the windows following Cessna Service Bulletin 56-4\n\n**When it must be done:**\n- **First inspection:** Before the aircraft reaches 400 hours of flight time\n- **Repeat inspections:** Every 100 hours of flight time thereafter\n- **Permanent fix:** Install the improved windows before 1 September 1975\n\n**Why it matters:** Flight compartment windows are critical for pilot visibility and cabin pressurisation. This AD addresses a known defect or wear pattern that could lead to window failure — potentially causing rapid decompression or loss of visibility during flight. The repetitive inspection requirement suggests the defect develops over time with use."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-500-4-amdt-1-flight-compartment-side-windows-inspection-and-replacement","history":"/api/acts/ad-cessna-500-4-amdt-1-flight-compartment-side-windows-inspection-and-replacement/history","analysis":"/api/acts/ad-cessna-500-4-amdt-1-flight-compartment-side-windows-inspection-and-replacement/analysis","conflicts":"/api/acts/ad-cessna-500-4-amdt-1-flight-compartment-side-windows-inspection-and-replacement/conflicts","importantCases":"/api/acts/ad-cessna-500-4-amdt-1-flight-compartment-side-windows-inspection-and-replacement/important-cases","documents":"/api/acts/ad-cessna-500-4-amdt-1-flight-compartment-side-windows-inspection-and-replacement/documents"}}