{"id":"F2006B08209","name":"AD/CESSNA 320/3 - Nose Gear Main Drive Tube Assembly - Inspection","slug":"ad-cessna-320-3-nose-gear-main-drive-tube-assembly-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115434,"registerId":"commonwealth-F2006B08209-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 320/3 - Nose Gear Main Drive Tube Assembly - 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 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Cessna 320 Series Aeroplanes\n\n \n\n# AD/CESSNA 320/3 Nose Gear Main Drive Tube Assembly - Inspection\n\nApplicability: All models which have exceeded 1000 hours time in service.\n\n# 9/68\n\n \n\nRequirement: 1. Inspect the bearing P/N 4NBC612ZP for movement between the outer race and the eye end of the nose gear main drive tube P/N 0842120-1.\n\n \n\n2. If movement is found inspect the entire nose gear assembly for damage or incorrect adjustment. The inflation of the shock leg is of major importance.\n\n \n\nCompliance: Within 100 hours time in service from 5 September 1968 and there-after at intervals not exceeding 200 hours time in service.\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 is a discrete, single-issue airworthiness directive from 1968 addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original narrow safety purpose."},"complexity_factors":["Very short document (under 200 words)","Only 2 substantive requirements with clear conditional logic (if movement found → expanded inspection)","Single defined term implicitly understood ('time in service' — standard aviation term for flight hours)","No cross-references to other legislation or regulations","Simple compliance schedule with fixed time intervals","Straightforward applicability test (1000 hours threshold)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:**\nIt requires owners and operators of **Cessna 320 series aeroplanes** to inspect a specific part of the nose landing gear (the main drive tube assembly) for a dangerous mechanical fault.\n\n**Who it affects:**\nAnyone who owns or operates a Cessna 320 aircraft that has flown more than **1,000 hours**.\n\n**What must be done:**\n- **First inspection:** Check whether a specific bearing (part number 4NBC612ZP) is loose or moving where it connects to the nose gear drive tube.\n- **If movement is found:** Inspect the entire nose gear assembly for damage or incorrect setup — with special attention to the shock absorber's air pressure (\"inflation of the shock leg\").\n\n**When it must be done:**\n- **First time:** Within 100 hours of flying time after **5 September 1968**.\n- **Ongoing:** Repeat the inspection every **200 hours** of flying time thereafter.\n\n**Why it matters:**\nLoose or damaged nose gear components can cause landing gear collapse during takeoff or landing — a potentially catastrophic failure. This directive forces proactive inspection to catch problems before they cause accidents."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive sets a targeted inspection requirement for the nose gear main drive tube bearing on Cessna 320 series aeroplanes exceeding 1,000 hours time in service. The instrument’s scope is explicit and limited to that component and the related nose gear assembly, with specified compliance intervals. There is no text in the instrument that expands or narrows that scope beyond the stated applicability and inspection requirements."},"complexity_factors":["Narrow technical focus: single component (bearing P/N 4NBC612ZP) and assembly (nose gear main drive tube P/N 0842120-1).","Clear applicability threshold (all models with >1,000 hours time in service) reduces scope complexity.","Specified recurring inspection intervals (first within 100 hours from a date, then every 200 hours) are straightforward to implement.","Lack of quantitative tolerances or detailed inspection methodology creates interpretive ambiguity for maintenance personnel about what constitutes unacceptable \"movement\" or \"incorrect adjustment\".","Requirement to inspect the entire nose gear assembly if movement is found introduces potentially broad follow‑on work depending on findings.","Reference to shock-leg inflation as critically important is specific but does not provide precise inflation standards, adding practical judgment calls."],"plain_english_summary":"### What this directive does, in plain English\n\nThis airworthiness directive requires regular inspections of a specific part of the nose landing gear on Cessna 320 series aeroplanes. It applies to every Cessna 320 that has accumulated more than 1,000 hours of flying time (Applicability). Mechanically, it requires two actions:\n\n- Check the bearing (P/N 4NBC612ZP) for movement between its outer race and the eye end of the nose gear main drive tube (P/N 0842120-1). If that movement is present, the operator must:\n  1. Inspect the entire nose gear assembly for damage or incorrect adjustment, and\n  2. Pay particular attention to the inflation of the shock leg (Requirement 1 and 2).\n\n- Timing: the first inspection must be done within 100 hours time in service after 5 September 1968, and thereafter at intervals no greater than 200 hours in service (Compliance).\n\nThe directive is issued under the Civil Aviation safety regulatory framework (header). The document specifies the parts by part-number and gives a repeat inspection interval; it does not provide a detailed inspection technique or corrective procedures beyond inspecting for movement, damage, and incorrect adjustment (Requirement 1–2).\n\n### Who this affects\n\n- Aircraft operators and owners of Cessna 320 series aeroplanes that have more than 1,000 hours time in service (Applicability).\n- Maintenance personnel who must perform the inspections and any follow-up work (Requirement 1–2; Compliance).\n\n### Why it matters (as the document states)\n\nThe directive’s explicit purpose is to detect movement of the bearing relative to the drive tube eye and, if movement is found, to ensure the entire nose gear assembly is free from damage or incorrect adjustment and that the shock-leg inflation is correct (Requirement 1–2). Detecting these issues requires periodic checks at specified service-hour intervals (Compliance). \n\n### Costs, incentives and compliance burden (mechanical description, with source citations)\n\n- Who pays: aircraft owners/operators bear the direct cost of inspections, any follow-up inspections, adjustments, repairs, parts and labour caused by this directive (Applicability; Requirement 1–2; Compliance). The directive itself does not state who pays, but it imposes the inspection requirement on operators of the affected aeroplanes.\n\n- Compliance burden and operational impact: operators must schedule a first inspection within 100 hours in service from the stated date and then perform inspections every 200 hours or less thereafter. These inspections create recurring maintenance work and associated aircraft downtime (Compliance).\n\n- Discretion and technical ambiguity: the directive instructs personnel to look for “movement” and for “damage or incorrect adjustment” but does not define quantitative tolerances, an approved inspection method, or corrective thresholds. The note that “the inflation of the shock leg is of major importance” highlights a specific point to check but leaves the exact standard to the inspector or maintenance organisation (Requirement 1–2). That lack of technical detail creates some judgment for maintenance staff about what constitutes unacceptable movement or incorrect adjustment.\n\n- Incentives and trade-offs: operators must balance inspection and repair costs and aircraft availability against the risk of undetected nose gear problems. The directive channels operator behaviour toward routine, scheduled inspections of the specified bearing and gear assembly (Applicability; Requirement 1–2; Compliance).\n\n### Implementation and practical points\n\n- The directive is narrowly targeted by part numbers and by aircraft model/hours-in-service threshold (Applicability; Requirement 1).\n- It mandates repeated inspections on a fixed service-hour basis rather than being tied to calendar time (Compliance).\n- Because the AD does not include precise inspection techniques or acceptance criteria, operators will rely on their maintenance procedures, approved maintenance manuals, or regulatory guidance to interpret and implement the checks (Requirement 1–2).\n\n(Referenced source clauses: Applicability; Requirement 1 and 2; Compliance.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-320-3-nose-gear-main-drive-tube-assembly-inspection","history":"/api/acts/ad-cessna-320-3-nose-gear-main-drive-tube-assembly-inspection/history","analysis":"/api/acts/ad-cessna-320-3-nose-gear-main-drive-tube-assembly-inspection/analysis","conflicts":"/api/acts/ad-cessna-320-3-nose-gear-main-drive-tube-assembly-inspection/conflicts","importantCases":"/api/acts/ad-cessna-320-3-nose-gear-main-drive-tube-assembly-inspection/important-cases","documents":"/api/acts/ad-cessna-320-3-nose-gear-main-drive-tube-assembly-inspection/documents"}}