{"id":"F2006B07619","name":"AD/Y12/5 - Aileron Spar Balance Support","slug":"ad-y12-5-aileron-spar-balance-support","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":50335,"registerId":"commonwealth-F2006B07619-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\n![](image.001.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nHarbin Y12 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/Y12/5 Aileron Spar Balance Support 3/","sectionType":"part","heading":"AD/Y12/5 Aileron Spar Balance Support 3/2003","content":"# AD/Y12/5 Aileron Spar Balance Support 3/2003\n\nApplicability: All Model Y12 aircraft.\n\nRequirement: Action in accordance with Harbin Aircraft Service Bulletin No. Y12-57-0056R1.\n\nNote: China CAAC AD CAD95-Y012-01R1 refers.\n\nCompliance: Unless the requirements of this Directive have been previously accomplished, accomplish the following:\n\n    For aircraft that have accumulated less than 2,000 flight hours as of 20 March 2003, inspect in accordance with the Requirement document. If defects as described in the Requirement document are evident, incorporate the reinforcement in accordance with the Requirement document before further flight.\n\n    2. For aircraft that have accumulated more than 2,000 flight hours as of 20 March 2003, incorporate the reinforcement in accordance with the Requirement document before 30 March 2003.\n\nThis Airworthiness Directive becomes effective on 20 March 2003.\n\nBackground: This Directive requires incorporation of a modification to increase the strength of the connection of the aileron balance support and the aileron spar.\n\n![Signature of David Alan Villiers Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nDavid Alan Villiers\n\nDelegate of the Civil Aviation Safety Authority 29 January 2003\n\n![](image.001.png)","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"This Directive implements a specific, model-targeted structural modification to address an identified unsafe condition. It follows the manufacturer\u0002s Service Bulletin and references a prior CAAC AD; it does not broaden regulatory scope beyond correcting that condition. There is no indication in the text that the Directive expanded into matters beyond the original technical safety purpose."},"complexity_factors":["Very short instrument (one-page AD style)","Single defined applicability (\"All Model Y12 aircraft\")","One external normative reference (Harbin Service Bulletin No. Y12-57-0056R1)","Single conditional branching based on a 2,000 flight-hour threshold","Two compliance timelines (inspect-and-fix before next flight for <2,000 h; mandatory modification before 30 March 2003 for >2,000 h)","Reference to a foreign AD (China CAAC AD CAD95-Y012-01R1) but no further cross-references","Limited regulatory discretion (prescriptive: follow the Service Bulletin)"],"plain_english_summary":"**What this instrument does (mechanics)\n\n- Applies to: all Harbin Y12 model aeroplanes (see \"Applicability\").\n- Requires: operators to follow Harbin Aircraft Service Bulletin No. Y12-57-0056R1 (see \"Requirement\") to modify/reinforce the connection between the aileron balance support and the aileron spar.\n- Timing / deadlines (see \"Compliance\"):\n  - If an aircraft had fewer than 2,000 flight hours as of 20 March 2003: carry out an inspection per the Service Bulletin; if the inspection finds the defects described in the Service Bulletin, install the reinforcement before the next flight.\n  - If an aircraft had more than 2,000 flight hours as of 20 March 2003: incorporate the reinforcement in accordance with the Service Bulletin no later than 30 March 2003.\n- Becomes effective: 20 March 2003.\n- Background statement: the stated purpose is to increase the strength of the connection between the aileron balance support and the aileron spar (the structural joint that links the aileron counterbalance to the aileron main spar).\n\n**Who is affected\n\n- Primary cost-bearers: owners and operators of Harbin Y12 aircraft. They must arrange inspections and, where required, the reinforcing modification.\n- Service providers: licensed maintenance organisations or suitably authorised engineers who will perform the inspections and modifications and source any parts called for by the Service Bulletin.\n- Regulator: CASA (the delegated official issued the Directive) is the enforcing authority.\n\n**Why the Directive matters (official claim and practical effects)\n\n- Official claim: the Directive corrects an \"unsafe condition\" by strengthening the aileron balance support to the aileron spar (see \"Background\"). That is, it aims to reduce the risk of structural failure at that connection.\n\n- Practical effects and trade-offs:\n  - Safety benefit (concentrated): the modification directly increases the structural strength at a specific aircraft joint for each modified airframe.\n  - Cost (concentrated): operators pay for labour, parts and downtime while the inspection or modification is performed. Aircraft above 2,000 hours faced a short compliance window (must be done by 30 March 2003), which can force rapid grounding or rearrangement of schedules.\n  - Administrative burden: operators must obtain and follow an external manufacturer Service Bulletin (Y12-57-0056R1). That creates dependence on the availability of the bulletin, parts and approved maintenance capability.\n  - Competition and market effects: the Directive does not alter ownership, market access or pricing mechanics directly; it imposes a compliance cost on operators of a specific model. Independent maintenance providers able to perform the work can compete to supply the service if they are certified to do so.\n  - Enforcement and discretion: the Directive is prescriptive (\"do the Service Bulletin\"). There is limited room for operator discretion unless the Service Bulletin explicitly allows alternative methods; CASA enforces compliance.\n\n**Implementation risks and practical issues to watch\n\n- Parts and labour availability: if parts called for by the Service Bulletin are scarce, operators may face delays or higher costs.\n- Inspection judgement: for aircraft under 2,000 hours, the requirement is to inspect and then act only if defects as described are evident. That places weight on the inspector's interpretation of what constitutes the defect described in the Service Bulletin.\n- Short deadline for higher-utilisation aircraft: the window to comply for aircraft over 2,000 hours is brief (10 days after the Directive took effect), increasing the risk of operational disruption.\n- Reliance on external documentation and foreign authority: the AD refers to a Harbin Service Bulletin and notes a China CAAC AD. CASA enforces, but the technical instructions come from the manufacturer/CAAC.\n\n**Where this text says it (key sections)\n- Applicability: \"All Model Y12 aircraft.\" \n- Requirement: \"Action in accordance with Harbin Aircraft Service Bulletin No. Y12-57-0056R1.\" \n- Compliance: two-part timing rule tied to 2,000 flight hours and specific dates. \n- Background: identifies the unsafe condition and the required strengthening.\n\n**Bottom line (short)\nOperators of Harbin Y12 aeroplanes must inspect and/or modify the aileron balance support-to-spar connection per the manufacturer\u0002s Service Bulletin. The measure aims to address a structural safety concern; it imposes direct costs and possible short-term grounding on affected operators, with limited discretion beyond following the Service Bulletin."},"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":2,"scope_assessment":{"changed":false,"description":"This is a standard, targeted airworthiness directive addressing a specific structural defect in a particular aircraft model. The scope remains precisely limited to the aileron spar balance support modification as originally intended."},"complexity_factors":["Very short document (approximately 250 words)","Only 1 defined term implicitly referenced (the Service Bulletin)","Simple conditional structure based solely on flight hours threshold (2,000 hours)","No cross-references to other legislation beyond a single note referencing a Chinese aviation directive","Clear, single requirement with two straightforward compliance paths","No nested exceptions or complex temporal calculations beyond fixed dates"],"plain_english_summary":"This CASA safety order mandates owners/operators of Harbin Y12 aeroplanes to inspect and reinforce the aileron balance-support to aileron-spar connection to prevent possible structural failure and loss of control. Low-hour aircraft (<2,000 FH as of 20 Mar 2003) must inspect and ground if defects are found; high-hour aircraft (>2,000 FH) must be repaired immediately (by 30 Mar 2003). Compliance with Harbin Service Bulletin Y12-57-0056R1 is mandatory."}},"importantCases":[],"_links":{"self":"/api/acts/ad-y12-5-aileron-spar-balance-support","history":"/api/acts/ad-y12-5-aileron-spar-balance-support/history","analysis":"/api/acts/ad-y12-5-aileron-spar-balance-support/analysis","conflicts":"/api/acts/ad-y12-5-aileron-spar-balance-support/conflicts","importantCases":"/api/acts/ad-y12-5-aileron-spar-balance-support/important-cases","documents":"/api/acts/ad-y12-5-aileron-spar-balance-support/documents"}}