{"id":"F2006B05082","name":"AD/CESSNA 180/7 Amdt 2 - Undercarriage Attachment Bolts","slug":"ad-cessna-180-7-amdt-2-undercarriage-attachment-bolts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44992,"registerId":"commonwealth-F2006B05082-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 180/7 Amdt 2 - Undercarriage Attachment Bolts","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 180, 182 and Wren 460 Series Aeroplanes\n\n \n\n# AD/CESSNA 180/7\n\nAmdt 2\n\nApplicability: All 180 series.\n\n# Undercarriage Attachment Bolts 11/71\n\n \n\nRequirement: Remove the AN7-20A bolts and the nuts attaching the inboard end of the undercarriage spring legs and replace with new AN7-20A bolts and new nuts.\n\n \n\nCompliance: At intervals not exceeding 500 hours time in service. For aircraft which have exceeded 500 hours time in service since last bolt replacement - Within 100 hours time in service after 30 November 1971 and thereafter as above.\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":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is Amendment 2 of an Airworthiness Directive originally issued in November 1971. The scope remains tightly focused on the original safety issue: preventing undercarriage bolt failure on Cessna 180 aircraft. There is no evidence of scope creep; the amendment appears to be a routine update to the original directive."},"complexity_factors":["Extremely short document — only 4 substantive paragraphs","Only one defined term implied ('time in service')","No cross-references to other legislation or regulations","Single, straightforward mechanical requirement with one simple compliance schedule","No conditional logic, exceptions, or nested provisions","Clear applicability statement ('All 180 series')"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It applies to all **Cessna 180 series aircraft**.\n\n**What it requires:**\nOwners and operators must **replace specific bolts** (called AN7-20A bolts) and nuts that attach the undercarriage (landing gear) spring legs to the aircraft. These bolts must be replaced with **new** bolts and nuts — you can't reuse the old ones.\n\n**When you must do this:**\n- **Every 500 hours of flight time** (\"time in service\" means actual flying hours, not just calendar time)\n- For aircraft that had already flown more than 500 hours since their last bolt replacement when this rule came out: they got a short grace period — **within 100 flight hours after 30 November 1971**, then every 500 hours after that\n\n**Why it matters:**\nUndercarriage bolts are critical safety components. If they fail, the landing gear could collapse during takeoff or landing. This AD prevents metal fatigue and wear from causing catastrophic failures by mandating regular replacement of these high-stress parts."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The supplied text sets a clear, narrowly focused requirement for replacement of a specific bolt/nut assembly on all Cessna 180 series aircraft and defines the compliance interval. The document does not indicate any expansion or narrowing of that scope relative to an earlier instrument; no information in the provided text identifies a change from an original intent."},"complexity_factors":["Single, narrowly specified technical action (replace AN7-20A bolts and nuts).","Clear applicability (all Cessna 180 series).","Simple, fixed compliance interval (every 500 hours; transitional 100-hour deadline for overdue aircraft).","No alternative methods, exceptions, or conditional branches stated in the text.","Absence of explanatory, enforcement, or approval provisions increases practical uncertainty about compliance verification but does not add procedural complexity to the action itself."],"plain_english_summary":"What this instrument does (mechanically)\n\n- It requires removal and replacement of a specific bolt and nut assembly on certain Cessna aircraft. The exact item named is the AN7-20A bolt and its nut used to attach the inboard end of the undercarriage (landing gear) spring legs. (Requirement)\n- It applies to \"All 180 series\" aircraft. (Applicability)\n- It sets a recurring compliance interval: replace those bolts and nuts at intervals not exceeding 500 hours time-in-service. For aircraft that have already gone more than 500 hours since the last bolt replacement, the replacement must be done within 100 hours time-in-service after 30 November 1971; after that the 500-hour repeating interval applies. (Compliance)\n\nWho this affects and who pays\n\n- Aircraft owners and operators of Cessna 180 series aeroplanes are the parties required to carry out the work. The text identifies the affected fleet: \"All 180 series.\" (Applicability)\n- The owners/operators will incur the direct costs: purchasing replacement AN7-20A bolts and new nuts, and paying labour to remove and refit the undercarriage spring leg attachments. These costs arise from the mandatory replacement actions set out in the Requirement and Compliance sections.\n\nWhy it matters (what the text says and what it implies)\n\n- The instrument does not include an explanatory statement or an explicit rationale in the supplied text. It prescribes a specific maintenance action and a fixed compliance timetable (Requirement; Compliance).\n\nPractical effects, incentives and trade-offs\n\n- Behaviour change required: owners/operators must schedule and perform recurring replacements of the named bolts and nuts according to the stated hours-in-service intervals. (Requirement; Compliance)\n- Record-keeping incentive: because the directive's timing depends on hours since the last bolt replacement, operators are incentivised to keep accurate maintenance and time-in-service records to avoid missing the required window. (Compliance)\n- Costs and opportunity cost: owners incur material and labour expense at each replacement interval. Those resources cannot be used for other maintenance/uses during the work window. (Requirement; Compliance)\n- Implementation risk and compliance burden: the directive prescribes a specific part number and fixed intervals, leaving little operational discretion in whether or when to comply beyond the stated windows. The supplied text does not specify enforcement mechanisms or permitted alternatives, and provides no exemptions or variations. (Requirement; Compliance)\n- Substitution effects: the text requires replacement with the same part designation (new AN7-20A bolts and new nuts). It does not authorise use of alternative parts or mitigations in the supplied text. (Requirement)\n\nDecision and discretion\n\n- The instrument centralises the compliance decision in the rule: it mandates the action and the timing. The supplied text does not grant discretion to operators to defer, substitute parts, or vary the interval. (Requirement; Compliance)\n\nSource citations (where applicable):\n- Applicability: \"All 180 series.\" (Applicability)\n- Requirement: \"Remove the AN7-20A bolts and the nuts attaching the inboard end of the undercarriage spring legs and replace with new AN7-20A bolts and new nuts.\" (Requirement)\n- Compliance: \"At intervals not exceeding 500 hours time in service. For aircraft which have exceeded 500 hours time in service since last bolt replacement - Within 100 hours time in service after 30 November 1971 and thereafter as above.\" (Compliance)\n\nLimitations of this summary\n\n- The supplied text contains the mandatory action and the compliance timetable but does not include an explicit explanatory memorandum, safety analysis, or enforcement provisions. This summary limits itself to the requirements and observable practical effects stated in the text."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-180-7-amdt-2-undercarriage-attachment-bolts","history":"/api/acts/ad-cessna-180-7-amdt-2-undercarriage-attachment-bolts/history","analysis":"/api/acts/ad-cessna-180-7-amdt-2-undercarriage-attachment-bolts/analysis","conflicts":"/api/acts/ad-cessna-180-7-amdt-2-undercarriage-attachment-bolts/conflicts","importantCases":"/api/acts/ad-cessna-180-7-amdt-2-undercarriage-attachment-bolts/important-cases","documents":"/api/acts/ad-cessna-180-7-amdt-2-undercarriage-attachment-bolts/documents"}}