{"id":"F2006B11237","name":"AD/M20/33 - Main Landing Gear Retracting Link Bolt - Replacement","slug":"ad-m20-33-main-landing-gear-retracting-link-bolt-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56957,"registerId":"commonwealth-F2006B11237-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/M20/33 - Main Landing Gear Retracting Link Bolt - 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)  Mooney M20 Series Aeroplanes\n\n \n\nAD/M20/33 Main Landing Gear Retracting Link Bolt - Replacement\n\n\n7/78\n\n \n\nApplicability: All model M20F with S/Nos. 660003 to 22-1439. All model M20J with S/Nos.\n\n240001 to 240609.\n\n \n\nDocument: Mooney SB M20-212.\n\n \n\nCompliance: Within 100 hours time in service after 31 August 1978.\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":3,"scope_assessment":{"changed":true,"description":"The AD introduces a new mandatory maintenance requirement for the listed M20F and M20J serial-number ranges: the main landing gear retracting link bolt must be replaced within 100 hours time in service after 31 August 1978, to be carried out per Mooney SB M20-212. The directive therefore changes the maintenance obligations for owners/operators of those aircraft from whatever prior (non-mandatory or different) regime applied to a specific, time-bound mandatory replacement (Applicability, Document, Compliance)."},"complexity_factors":["Narrow applicability: applies only to two specific model/serial-number ranges (low scope complexity) (Applicability).","Single required action: a one-off replacement (simple action) (title, Compliance).","External dependency: implementation requires following Mooney Service Bulletin M20-212, adding a reliance on an external technical document (Document).","Fixed, short compliance window: must be done within 100 hours after a specified date, creating scheduling pressure but not procedural complexity (Compliance).","Lack of detail in text: the excerpt omits the causal rationale, parts availability, recordkeeping and enforcement mechanics, which creates uncertainty for implementers despite the directive itself being simple (title, Document, Compliance)."],"plain_english_summary":"What this directive does\n\n- The Civil Aviation Safety Authority (under Part 39 of the Civil Aviation Regulations) requires that the main landing gear retracting link bolt on certain Mooney M20 aeroplanes be replaced. (See title and header.)\n\nWhich aeroplanes are affected\n\n- All Mooney M20F aeroplanes with serial numbers 660003 through 22-1439. (Applicability)\n- All Mooney M20J aeroplanes with serial numbers 240001 through 240609. (Applicability)\n\nWhat the operator must do, and by when\n\n- Replace the specified main landing gear retracting link bolt in accordance with Mooney Service Bulletin M20-212. (Document)\n- Complete that replacement within 100 hours time in service after 31 August 1978. (Compliance)\n\nWhere the instruction for how to do the work comes from\n\n- The AD points to Mooney SB M20-212 as the procedural/document reference for the replacement. (Document)\n\nWhat the text says about purpose and risk\n\n- The AD text provided does not include an explicit statement of why the bolt must be replaced. The title describes the action (\"Main Landing Gear Retracting Link Bolt - Replacement\") but no hazard description or causal detail is supplied in the excerpt.\n\nPractical effects, incentives and costs (mechanics, not judgments)\n\n- Who pays: aircraft owners/operators of the listed M20F and M20J serial numbers will incur the direct costs of parts and labour required to carry out the bolt replacement. (Applicability, Compliance)\n- Who decides how to perform the work: the AD directs compliance with Mooney SB M20-212; operators follow that service bulletin for method and parts. (Document)\n- Timing and operational impact: the work must be done within the stated window (100 hours time in service after 31 Aug 1978). That creates a short-term scheduling requirement and potential aircraft downtime while the work is done. (Compliance)\n- Compliance burden: the AD imposes a single, time-bound maintenance action. The administrative burden is to schedule, procure parts, and document completion per regulatory procedures; the AD text itself does not set out recordkeeping or enforcement details in this excerpt. (Applicability, Document, Compliance)\n- Discretion and enforcement: the text is prescriptive about what must be done and when; it refers to an external service bulletin for the how. The AD is issued under CASA’s AD schedule (Part 39), so the authority to require the action is centralised, but the excerpt does not set out penalty or enforcement mechanics. (Header, Document)\n\nTrade-offs and implementation risks\n\n- The directive creates a definite short-term cost and logistical task for affected operators (parts, labour, downtime). (Applicability, Compliance)\n- The AD channels operators to a manufacturer service bulletin for the technical solution, concentrating technical discretion with the bulletin’s instructions. (Document)\n- The excerpt provides no information about availability of parts, alternative methods, or any phased compliance exceptions; those practical issues could affect scheduling and cost but are not described here. (Document, Compliance)\n\nNet effect in plain terms\n\n- If you own or operate a Mooney M20F or M20J within the listed serial ranges, you must replace the main landing gear retracting link bolt as directed by Mooney SB M20-212, and you must complete that work within 100 hours time in service after 31 August 1978. The AD sets who must act, what to consult for the technical steps, and the time window for compliance, but the excerpt does not state the specific safety rationale or enforcement details."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific aircraft. It has not expanded beyond its original purpose of mandating a single bolt replacement."},"complexity_factors":["Very short document (approximately 150 words)","Only 2 defined applicability criteria (aircraft model and serial number ranges)","Single, unambiguous compliance requirement (replace bolt within 100 hours)","No cross-references to other legislation beyond the enabling regulation (Part 39)","No conditional logic or exceptions","Straightforward command structure: applicability → document reference → compliance deadline"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** issued by Australia's Civil Aviation Safety Authority (CASA). It mandates a safety fix for specific Mooney M20 model aeroplanes.\n\n**What it does:**\n- Requires owners/operators to **replace the main landing gear retracting link bolt** on affected aircraft.\n- This is a mandatory safety directive, not optional.\n\n**Who it affects:**\n- Owners and operators of **Mooney M20F aircraft** with serial numbers 660003 to 22-1439.\n- Owners and operators of **Mooney M20J aircraft** with serial numbers 240001 to 240609.\n\n**Why it matters:**\n- Landing gear failures can be catastrophic. This AD addresses a specific mechanical defect in the retracting link bolt that could compromise the main landing gear's integrity.\n- Compliance is mandatory within **100 hours of flight time** after 31 August 1978.\n\n**Key details:**\n- **Compliance deadline:** Within 100 hours \"time in service\" (meaning actual flying hours, not calendar time) after 31 August 1978.\n- **Technical reference:** Mooney Service Bulletin M20-212 (the manufacturer's official repair instructions).\n- **Legal basis:** Civil Aviation Regulations 1998, Part 39 (the rules that give CASA power to issue mandatory safety directives)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-m20-33-main-landing-gear-retracting-link-bolt-replacement","history":"/api/acts/ad-m20-33-main-landing-gear-retracting-link-bolt-replacement/history","analysis":"/api/acts/ad-m20-33-main-landing-gear-retracting-link-bolt-replacement/analysis","conflicts":"/api/acts/ad-m20-33-main-landing-gear-retracting-link-bolt-replacement/conflicts","importantCases":"/api/acts/ad-m20-33-main-landing-gear-retracting-link-bolt-replacement/important-cases","documents":"/api/acts/ad-m20-33-main-landing-gear-retracting-link-bolt-replacement/documents"}}