{"id":"F2006B07336","name":"AD/TB20/31 - Main Landing Gear","slug":"ad-tb20-31-main-landing-gear","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49395,"registerId":"commonwealth-F2006B07336-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TB20/31 - Main Landing Gear","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)  Aerospatiale (Socata) TB20 (Trinidad) Series Aeroplanes\n\n \n\nAD/TB20/31 Main Landing Gear 8/95 DM\n\nApplicability: TB20 and TB21 aircraft, on which the ring on the attachment bearing of the LH or RH main landing gear has been removed and replaced during maintenance.\n\n \n\nRequirement: Action in accordance with Socata TB Service Bulletin SB10.091.57.\n\n \n\nNote: DGAC AD 95-084(A) refers.\n\n \n\nCompliance: Within 50 hours time in service after 31 May 1995, or prior to 31 July 1995, whichever occurs first.\n\n \n\nBackground: This Directive is issued to ensure that the rings, when replaced, have been correctly installed on the attachment bearing of the hinged strut.\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, time-limited safety directive addressing a specific mechanical defect in specific aircraft. It has not expanded beyond its original purpose of ensuring correct installation of landing gear rings."},"complexity_factors":["Single, specific applicability criterion (TB20/TB21 aircraft with specific maintenance history)","Single requirement referencing an external technical document (Service Bulletin) rather than spelling out detailed steps","Simple compliance deadline structure (whichever occurs first of two dates)","No defined terms section, no cross-references to other legislation beyond a note about a French aviation authority directive","Extremely short document (approximately 150 words of substantive content)","No conditional logic, exceptions, or nested provisions"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of certain Socata TB20 and TB21 aeroplanes to inspect or fix the main landing gear (the wheels that support the plane on the ground). Specifically, it targets planes where the \"ring on the attachment bearing\" of the left or right main landing gear has been removed and replaced during maintenance.\n\n**Who must comply:**\nAnyone who owns or operates a TB20 or TB21 aircraft that has had this specific maintenance work done on its main landing gear.\n\n**What they must do:**\nFollow the instructions in **Socata Service Bulletin SB10.091.57** — a technical document from the aircraft manufacturer detailing exactly what inspection or repair is required.\n\n**When they must do it:**\nWithin 50 hours of flying time after 31 May 1995, OR before 31 July 1995 — whichever comes first. (This is a historical directive from 1995, so compliance would have been required decades ago for operational aircraft at that time.)\n\n**Why it matters:**\nThe directive was issued because incorrectly installed rings on the landing gear attachment bearing could cause the landing gear to fail — potentially leading to a collapse during landing, taxiing, or takeoff. This is a \"better safe than sorry\" measure to prevent accidents."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD’s scope matches its stated purpose in the Background: it targets only TB20 and TB21 aircraft on which the attachment-bearing ring has been removed and replaced (Applicability; Background). There is no textual indication in the AD that the scope extends beyond that original focus; the requirement simply mandates action in accordance with the manufacturer’s service bulletin within the specified compliance window (Requirement; Compliance)."},"complexity_factors":["Narrow applicability: applies only to TB20/TB21 aircraft where the LH or RH attachment-bearing ring was removed and replaced (Applicability).","Single prescriptive obligation: directs compliance with one manufacturer service bulletin (Requirement).","Short, fixed compliance window: 50 hours TIS after 31 May 1995 or before 31 July 1995 (Compliance).","Dependence on an external document (Socata TB SB10.091.57) for procedural details (Requirement).","Regulatory provenance clear and limited: issued under Part 39 by the Civil Aviation Safety Authority (header), reducing interpretive discretion."],"plain_english_summary":"This AD requires owners/operators of Socata TB20/TB21 aircraft — but only those where the LH or RH attachment-bearing ring was removed and replaced — to carry out the inspection and corrective work specified in Socata Service Bulletin TB SB10.091.57. Work must be done within 50 hours TIS after 31 May 1995 or by 31 July 1995. Owners bear the cost; the rule ensures rings were correctly installed to maintain airworthiness."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tb20-31-main-landing-gear","history":"/api/acts/ad-tb20-31-main-landing-gear/history","analysis":"/api/acts/ad-tb20-31-main-landing-gear/analysis","conflicts":"/api/acts/ad-tb20-31-main-landing-gear/conflicts","importantCases":"/api/acts/ad-tb20-31-main-landing-gear/important-cases","documents":"/api/acts/ad-tb20-31-main-landing-gear/documents"}}