{"id":"F2006B07567","name":"AD/VAT/33 - Control Column Bearing Spigot Bolt - Inspection","slug":"ad-vat-33-control-column-bearing-spigot-bolt-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":50163,"registerId":"commonwealth-F2006B07567-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/VAT/33 - Control Column Bearing Spigot Bolt - 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)  Victa and A.E.S.L. Airtourer Series Aeroplanes\n\n \n\nAD/VAT/33 Control Column Bearing Spigot Bolt - Inspection 10/68\n\nApplicability: Airtourer 100 and 115.\n\n \n\nRequirement: Inspect the control column torque tube near bearing spigot bolt P/N 31724/1 for conformity with 6/15-24 WNF-2A threadform.\n\n \n\nNote: The outside diameter of this thread should be 0.3042 inches minimum and the root diameter should be 0.2536 inches minimum.\n\n \n\nCompliance: Within 100 hours time in service after 6 October 1968 or before installation after 6 October 1968 whichever occurs first.\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":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-limited safety directive from 1968. It has not expanded beyond its original narrow purpose of inspecting a specific bolt on specific aircraft models."},"complexity_factors":["Single, specific mechanical inspection requirement","Only two aircraft models affected (Airtourer 100 and 115)","One defined part number (P/N 31724/1)","Simple compliance condition: time-based deadline or pre-installation check","No cross-references to other legislation or regulations","No nested exceptions or conditional logic","Technical but straightforward measurement specifications"],"plain_english_summary":"This is an **Airworthiness Directive** — 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 **Victa and A.E.S.L. Airtourer 100 and 115 aeroplanes** to inspect a specific bolt on the control column (the steering mechanism). The bolt must meet precise thread measurements to ensure it won't fail during flight.\n\n**Who it affects:**\nAnyone who owns, operates, or maintains these specific light aircraft models.\n\n**Why it matters:**\nControl column failures can cause loss of aircraft control. This directive prevents potential accidents by catching defective bolts before they cause problems. The compliance deadline was strict — within 100 hours of flying time after October 1968, or before installing a new part.\n\n**Key detail:** The bolt must have a thread outside diameter of at least 0.3042 inches and a root diameter of at least 0.2536 inches."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The instrument’s scope is tightly limited to inspection of the control column torque tube at the bearing spigot bolt P/N 31724/1 on Airtourer 100 and 115 aeroplanes, with a single threadform specification and a single compliance window. The AD text supplied does not indicate any change from that narrowly stated scope."},"complexity_factors":["Single, narrowly defined applicability (Airtourer 100 and 115). (Applicability)","Single, specific physical measurement required (6/15-24 WNF-2A threadform with two numeric minima). (Requirement; Note)","Fixed and short compliance window tied to a date and service hours rather than an ongoing program. (Compliance)","Lack of prescribed measurement method or tolerances for instruments leaves implementation choices to inspectors. (Note; Requirement)","Use of imperial units and a specific part number (P/N 31724/1) requires reference to legacy specifications or parts lists for some implementers. (Requirement; Note)"],"plain_english_summary":"What this directive does (mechanical change)\n\n- Requires an inspection of the control column torque tube at or near the bearing spigot bolt with part number 31724/1 on Victa / A.E.S.L. Airtourer 100 and 115 aeroplanes. (Applicability; Requirement)\n- The inspection must check that the thread conforms to the 6/15-24 WNF-2A threadform. The AD gives minimum dimensions: outside diameter at least 0.3042 inches and root diameter at least 0.2536 inches. (Requirement; Note)\n- The inspection must be completed within 100 hours time in service after 6 October 1968, or, if the part is installed after that date, before that installation occurs—whichever comes first. (Compliance)\n\nStated purpose\n\n- The directive’s stated action is to verify the thread dimensions of a specific bolt location (Requirement; Note). The text does not set out consequences or remedies for a non-conforming measurement beyond the inspection requirement itself.\n\nWho pays and who decides\n\n- Owners/operators of Airtourer 100 and 115 aircraft are the parties required to comply because the AD applies to those models (Applicability). They (or their contracted maintenance provider) will carry out and pay for the inspection and any follow-up work needed to meet the directive’s requirement (Compliance; Requirement).\n- The AD specifies the part number to be inspected (P/N 31724/1) and the dimensional pass/fail limits (Note). The person performing the inspection must decide whether a given thread meets the specified dimensions; the AD does not prescribe a detailed measurement procedure. (Requirement; Note)\n\nPractical costs, incentives and trade-offs\n\n- Direct compliance costs are the time and labour to access and measure the thread on the torque tube and any measurement tooling required. Those costs fall on the aircraft owner/operator or their maintenance provider. (Compliance; Requirement)\n- If inspection reveals a dimension outside the stated minima, the AD’s text does not specify the remedial action; in that event owners/operators will need to decide on repair or replacement and bear its cost. (Requirement; Note)\n- The compliance timeframe (within 100 hours TIS from 6 Oct 1968, or before installation thereafter) imposes a scheduling constraint: operators must allocate maintenance hours within that window or delay installation until the check is done. That creates a potential short-term operational cost (Compliance).\n- The AD targets a single, identified part and location (P/N 31724/1). That focus concentrates the requirement (and any benefits of inspection) on operators using that specific component. The costs of compliance are borne individually by those operators. (Applicability; Requirement)\n\nImplementation risk and inspector discretion\n\n- The AD states dimensional minima but does not prescribe the exact measurement technique, instrument tolerance, or acceptance procedure; that leaves methodological choices to the inspector or maintenance organisation. This creates a source of implementation discretion and possible measurement variability. (Note; Requirement)\n\nEffects on private activity and markets\n\n- The directive imposes a narrowly targeted maintenance requirement on owners/operators of the specified Airtourer models. The practical market effects are limited to additional maintenance demand for inspection and any subsequent repair or replacement of non-conforming parts. The AD does not create ongoing regulatory fees or changes to ownership or operating rights in the text provided. (Applicability; Requirement; Compliance)\n\nNet description\n\n- Mechanically, the AD is a one-off inspection requirement with a fixed compliance window for a specified bolt and threadform on Airtourer 100 and 115 aeroplanes. Operators must measure the thread against the listed minima and schedule that work within the stated time constraints. (Applicability; Requirement; Note; Compliance)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-vat-33-control-column-bearing-spigot-bolt-inspection","history":"/api/acts/ad-vat-33-control-column-bearing-spigot-bolt-inspection/history","analysis":"/api/acts/ad-vat-33-control-column-bearing-spigot-bolt-inspection/analysis","conflicts":"/api/acts/ad-vat-33-control-column-bearing-spigot-bolt-inspection/conflicts","importantCases":"/api/acts/ad-vat-33-control-column-bearing-spigot-bolt-inspection/important-cases","documents":"/api/acts/ad-vat-33-control-column-bearing-spigot-bolt-inspection/documents"}}