{"id":"F2006B02564","name":"AD/AUS/12 Amdt 1 - Tailplane Attachment Stubs and Leading Edge Tubes","slug":"ad-aus-12-amdt-1-tailplane-attachment-stubs-and-leading-edge-tubes","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41820,"registerId":"commonwealth-F2006B02564-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AUS/12 Amdt 1 - Tailplane Attachment Stubs and Leading Edge Tubes","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nAuster/Beagle A.61 Series Aeroplanes\n\nAD/AUS/12\n\nAmdt 1\n\nApplicability: All models.\n\n  \n\nTailplane Attachment Stubs and Leading Edge Tubes\n\n  \n3/96\n\nRequirement: 1. Install a tailplane safety tube and safety split pin in accordance with Auster Modification numbers 2555 and 3234.\n\n    2. Remove the tailplane and sufficient fabric to ensure complete access to the area to be inspected and inspect :\n\n    the tailplane attachment stubs for cracking in the vicinity of the bolt holes, and\n\n    b. on tailplanes of brazed construction, which are those with serial numbers before AUS 697 GD/W and AUS 698 GD/W, inspect the root ends of the leading edge tubes for cracking, particularly in the vicinity of the brazed saddle washers at the attachment bolt holes.\n\nNote: It is strongly recommended that the inspections be carried out using the dye penetrant method and that suitable tear-off patches be provided at the areas to be inspected.\n\nCompliance: 1. Prior to 30 September 1959.\n\n    2. Unless already accomplished within the two ysears prior to 29 February 1996, before 30 May 1996, thereafter:\n\n    for Auster J5F \\- at intervals not exceeding 100 hours time in service or two years, which ever occurs first; and\n\n    b. for all other models \\- at intervals not exceeding 250 hours time in service or two years, whichever occurs first.\n\nThe effective date of the initial issue of this Directive was 30 September 1959, and remains unchanged for Requirement paragraph 1.\n\nBackground: Amendment 1 is raised to include a calendar based periodicity for this Directive due to the current low utilisation of this Type, and following the inflight failure of a forward attachment tube due to corrosion.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"The original 1959 directive required a one-time hardware installation. Amendment 1 (1996) significantly expanded the scope by adding recurring calendar-based inspection requirements and differentiating inspection intervals by aircraft model. The rationale changed from a simple hardware fix to an ongoing corrosion-monitoring regime necessitated by changed operational patterns (low utilisation of vintage fleet)."},"complexity_factors":["Short, single-purpose document (2 requirements only)","Minimal defined terms (only 'time in service' implied)","Simple conditional structure: different inspection intervals for J5F model vs all others","One cross-reference to external documents (Auster Modification numbers 2555 and 3234)","Contains one obvious typographical error ('ysears' instead of 'years') suggesting limited drafting review","No nested exceptions or complex logical operators"],"plain_english_summary":"This mandatory CASA Airworthiness Directive targets all Auster/Beagle A.61 series aeroplanes, requiring fitting of a safety tube and split pin to the tailplane and repeated removal of tailplane covering for inspections for corrosion/cracks where the tailplane attaches (and on older models, at brazed leading-edge tubes). Prompted by an in‑flight tailplane failure, it affects owners, operators and maintenance engineers and adds calendar‑based (2‑year) inspection intervals to catch corrosion in low‑hour vintage aircraft."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 1 broadened the operational scope of the Directive by adding a calendar-based inspection periodicity (a two-year maximum interval) in addition to the existing hours‑based intervals. The original directive required a retrofit and likely hours‑based inspections; the amendment explicitly imposes time-based inspections to capture low‑utilisation aircraft that might not reach the hours thresholds. This change increases the number of mandatory inspections for aircraft that fly infrequently and was introduced following an in‑flight failure attributed to corrosion."},"complexity_factors":["Short document with limited provisions (two substantive Requirements).","Single simple conditional split: brazed-construction tailplanes (serial number cut-off) require an additional inspection item.","Two different periodicities depending on model (Auster J5F vs other models).","Calendar backstop (2 years) added on top of hours-based intervals — creates a small conditional cross-check.","Reference to historical dates (1959, 1996) which can confuse present-day reading but do not add structural complexity.","References to external modification documents (Auster Mod numbers) introduce dependency on other sources for full compliance details."],"plain_english_summary":"**What this directive requires (mechanics)**\n\n- **Install a safety tube and safety split pin on the tailplane** in accordance with Auster Modification numbers 2555 and 3234. (This is Requirement 1.)\n  - The installation was required to be completed by 30 September 1959 (the original effective date remains unchanged for this requirement).\n\n- **Inspect the tailplane attachment areas** by removing the tailplane and enough fabric to gain full access, and then:\n  - Inspect the **tailplane attachment stubs** for cracking around the bolt holes, and\n  - For tailplanes of **brazed construction** (identified by serial numbers before AUS 697 GD/W and AUS 698 GD/W), also inspect the **root ends of the leading edge tubes** for cracking, especially around the brazed saddle washers at the attachment bolt holes. (This is Requirement 2.)\n\n- **Recommended inspection technique:** The Directive strongly recommends dye-penetrant inspection and suggests using tear-off inspection patches at the inspected areas (this recommendation is non-mandatory wording in the Note).\n\n**When the work must be done (compliance timing)**\n\n- For the installation (Requirement 1): Prior to 30 September 1959 (historical requirement).\n\n- For the inspections (Requirement 2): Unless the inspection was already done within the two years prior to 29 February 1996, it had to be done by 30 May 1996. After that, periodic inspections are required as follows:\n  - **Auster J5F:** every 100 hours time-in-service (TIS) or every 2 years, whichever comes first.\n  - **All other models:** every 250 hours TIS or every 2 years, whichever comes first.\n\n**Why the change was made (official rationale)**\n\n- The amendment adds a **calendar-based periodicity** (the two‑year backstop) because these types are used infrequently; the calendar rule ensures inspections still occur even if hours flown are low. The amendment was prompted by an in-flight failure of a forward attachment tube attributed to corrosion.\n\n**Who is affected**\n\n- Owners, operators and maintenance organisations responsible for Auster/Beagle A.61 series aeroplanes (all serials, with extra inspection attention for brazed-construction tailplanes with serials before AUS 697 GD/W and AUS 698 GD/W).\n\n**Who pays and who decides**\n\n- Aircraft owners/operators pay for the parts, labour and downtime required for the retrofit and the inspections, and for any repairs revealed by the inspections.\n- Maintenance organisations perform the work to the specified Auster modification instructions; operators schedule and document compliance.\n\n**Practical effects, incentives and trade-offs**\n\n- The Directive forces a specific retrofit (the safety tube and split pin) where not already installed; that is a one-off cost but directly targets the mechanical risk that caused the failure.\n- It mandates periodic physical inspection of structure that may be hidden under fabric, which increases maintenance time and cost (removal and refit of fabric, dye-penetrant testing, possible repair or replacement of corroded/broken parts).\n- The calendar-based backstop (two-year cap) raises inspection frequency for low‑utilisation aircraft compared with relying on hours-only intervals, shifting costs from flight-active operators to low‑use owners who may otherwise have long gaps between inspections.\n- The requirement concentrates costs on a relatively small group (owners of this vintage type) while producing safety benefits that are diffuse (benefit to occupants and public safety). Owners have choices in response: schedule inspections, limit operations, or withdraw aircraft from service.\n- Implementation risks include availability of correct parts for vintage aircraft, need for technicians with experience on older construction methods (brazed joints), and the potential for inspections to uncover additional corrosion or structural work that increases cost and downtime.\n\n**Compliance and administrative notes**\n\n- The directive references specific Auster modification numbers for the retrofit; following those modification instructions is mandatory to meet Requirement 1.\n- The dye-penetrant method is recommended but the Directive does not make that method legally mandatory in the Note — operators should follow accepted maintenance standards and any applicable maintenance organisation procedures.\n\n(References: Requirement 1 and Requirement 2; Compliance paragraphs; Background.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-aus-12-amdt-1-tailplane-attachment-stubs-and-leading-edge-tubes","history":"/api/acts/ad-aus-12-amdt-1-tailplane-attachment-stubs-and-leading-edge-tubes/history","analysis":"/api/acts/ad-aus-12-amdt-1-tailplane-attachment-stubs-and-leading-edge-tubes/analysis","conflicts":"/api/acts/ad-aus-12-amdt-1-tailplane-attachment-stubs-and-leading-edge-tubes/conflicts","importantCases":"/api/acts/ad-aus-12-amdt-1-tailplane-attachment-stubs-and-leading-edge-tubes/important-cases","documents":"/api/acts/ad-aus-12-amdt-1-tailplane-attachment-stubs-and-leading-edge-tubes/documents"}}