{"id":"F2006B11380","name":"AD/MU-2/5 Amdt 3 - Wing Structural Fatigue Limitation","slug":"ad-mu-2-5-amdt-3-wing-structural-fatigue-limitation","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":57281,"registerId":"commonwealth-F2006B11380-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/MU-2/5 Amdt 3 - Wing Structural Fatigue Limitation","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)  Mitsubishi MU-2 Series Aeroplanes\n\n \n\nAD/MU-2/5\n\nAmdt 3\n\n\nWing Structural Fatigue Limitation 4/79\n\n \n\nApplicability: MU-2B-30 and MU-2B-36A aircraft.\n\n \n\nRequirement: 1. Retire from service the outer wing front spar joint fitting.\n\n \n\n![](image.002.png)2. Retire the aircraft from service.\n\n \n\nCompliance:\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\nNote 1: The lives for the MU-2B-36A are conservative interim values and will be reviewed on receipt of further data from the manufacturer.\n\n \n\nNote 2: Similar restrictions may be applied to other Models of the type should they enter the Australian Register.\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":4,"scope_assessment":{"changed":true,"description":"This instrument is labelled an amendment (Amdt 3), and it imposes mandatory retirement of a specified wing fitting and the affected aircraft types (Requirement: 1–2). The directive explicitly treats the MU-2B-36A lives as conservative interim values to be reviewed on receipt of further manufacturer data (Note 1), indicating an adjustment from earlier limits pending new information. It also states that similar restrictions may be applied to other models entering the Australian Register (Note 2), which extends the potential scope beyond the two named models."},"complexity_factors":["Mandatory removal of a structural component and possible whole-aircraft retirement — simple in effect but high operational cost for owners (Requirement: 1–2).","Applicability limited to two specific models, with a stated possibility of extension to other models (Applicability; Note 2), which creates conditional scope expansion.","Reference to \"conservative interim values\" for MU-2B-36A but no numeric life limits or compliance schedule provided in the supplied text (Note 1; Compliance: header present but details absent), creating practical ambiguity.","Dependence on external data from the manufacturer to review and possibly change the interim limits (Note 1) — outcome contingent on third-party information.","Enforcement and extension decisions rest with the regulator (Civil Aviation Safety Authority) and are not fully specified in the text (Note 2), leaving implementation timing and process uncertain."],"plain_english_summary":"### What this directive does, in plain language\n\n- This Airworthiness Directive applies to Mitsubishi MU-2B-30 and MU-2B-36A aeroplanes (Applicability). It requires two mechanical outcomes (Requirement):\n  1. The outer wing front spar joint fitting must be retired from service (Requirement: 1).  \n  2. The affected aircraft must be retired from service (Requirement: 2).\n\n- The instrument is an amendment (Amdt 3) to an earlier directive titled \"Wing Structural Fatigue Limitation\" and is issued by the Civil Aviation Safety Authority as part of the Schedule of Airworthiness Directives.\n\n### Why the directive exists (as stated)\n- The text includes an explicit note that the lives given for the MU-2B-36A are \"conservative interim values\" and will be reviewed when the manufacturer supplies further data (Note 1). This frames the action as precautionary pending more manufacturer information.\n- The directive also says similar restrictions may be applied to other models of the type if they enter the Australian Register (Note 2). That signals possible extension of the requirement beyond the two named models.\n\n### Who is affected and who decides\n- Aircraft owners and operators of MU-2B-30 and MU-2B-36A aeroplanes must comply (Applicability; Requirement). They bear the direct costs and operational consequences of removing parts and retiring aircraft.\n- The Civil Aviation Safety Authority enforces the directive and may apply similar restrictions to additional models (Note 2).\n\n### Practical effects, incentives and trade-offs\n- Direct mechanical effect: removal (retirement) of the outer wing front spar joint fitting (Requirement: 1) and removal of the whole aircraft from service (Requirement: 2). Those are mandatory actions for the specified registered aircraft.\n- Costs and who pays: owners/operators pay for inspection, part removal, disposition of retired parts, and the economic cost of decommissioning or replacing retired aircraft (Requirement: 1–2).\n- Compliance burden and uncertainty: the directive’s header \"Compliance:\" appears in the source but no specific compliance schedule or numeric life limits are included in the supplied text. That creates execution risk for operators who must know when and how to comply. The Note referring to \"conservative interim values\" for MU-2B-36A indicates numerical limits exist elsewhere or were intended to be specified, but they are not present in the supplied text (Note 1).\n- Regulatory discretion: CASA may extend the restriction to other MU-2 models if they are entered on the Australian Register (Note 2). The review of interim lives depends on manufacturer data (Note 1), so implementation relies on external information supplied to the regulator.\n- Trade-offs and opportunity cost: retiring fittings and aircraft removes operating capacity and may force owners to invest in replacements or exit service. The directive prioritises structural safety measures (as signalled by the interim-life approach) over continued operation of the affected aircraft until further data are available.\n\n### Implementation risks and information gaps in the supplied text\n- The directive text supplied lacks the specific numeric life limits, deadlines, or procedural steps under the \"Compliance:\" heading. That missing detail increases short-term compliance uncertainty for owners/operators.\n- The directive relies on manufacturer-supplied data to review the interim lives for MU-2B-36A; if that data are delayed or limited, the conservative restrictions may persist longer than necessary (Note 1).\n\n### Where these points are drawn from in the directive\n- Applicability: MU-2B-30 and MU-2B-36A (Applicability).  \n- Required actions: retire outer wing front spar joint fitting (Requirement: 1); retire the aircraft from service (Requirement: 2).  \n- Interim values and review: lives for MU-2B-36A are conservative interim values to be reviewed on receipt of further data from the manufacturer (Note 1).  \n- Possible extension to other models: similar restrictions may be applied to other models if they enter the Australian Register (Note 2).\n\nSummary: Mechanically, the directive forces removal of a specified wing fitting and retirement of the affected aircraft types from service. The regulator cites conservative interim life values for the MU-2B-36A and signals the potential to impose the same restriction on other MU-2 variants. The immediate costs and operational effects fall to aircraft owners and operators; the directive depends on manufacturer data for future revision and gives the regulator discretion to widen the measure."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope. It targets specific fatigue-related safety concerns in particular Mitsubishi MU-2 aircraft models. The document explicitly notes that similar restrictions may apply to other models if they enter the Australian register, but this represents a potential future expansion rather than scope creep from original intent. The core purpose—imposing flight hour limits due to wing structural fatigue—remains tightly focused."},"complexity_factors":["Very short document (approximately 200 words of substantive content)","Only 2 defined applicability criteria (specific aircraft models)","Simple two-step compliance requirement structure","No cross-references to other legislation or regulations","No conditional logic or nested exceptions","Minimal defined terms (only standard aviation terminology)","Clear, directive language ('Retire from service', 'Retire the aircraft')","Two brief notes providing context rather than legal complexity"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority for specific Mitsubishi MU-2 aircraft models.\n\n**What it does:**\n- Sets **strict limits on how long two specific aircraft models can keep flying** before they must be permanently grounded (\"retired from service\")\n- Specifically targets the **MU-2B-30 and MU-2B-36A** variants of the Mitsubishi MU-2 aircraft\n- Requires two things:\n  1. **Replace a critical wing part** (the outer wing front spar joint fitting) once it reaches its flight hour limit\n  2. **Ground the entire aircraft permanently** once it hits its overall flight hour limit\n\n**Why it matters:**\nThis directive exists because **metal fatigue** (when metal weakens after repeated stress from flights) poses a safety risk in these aircraft wings. The \"fatigue limitation\" means authorities have calculated how many flight hours these structures can safely handle before the risk of failure becomes unacceptable.\n\n**Who it affects:**\n- Owners and operators of these specific Mitsubishi MU-2 models in Australia\n- Pilots flying these aircraft\n- Maintenance organisations servicing these planes\n\n**Key notes:**\n- The limits for the MU-2B-36A model are described as temporary \"conservative\" values that may change when more data comes from the manufacturer\n- The authority warns that **other MU-2 models** could face similar restrictions if they enter the Australian aircraft register"}},"importantCases":[],"_links":{"self":"/api/acts/ad-mu-2-5-amdt-3-wing-structural-fatigue-limitation","history":"/api/acts/ad-mu-2-5-amdt-3-wing-structural-fatigue-limitation/history","analysis":"/api/acts/ad-mu-2-5-amdt-3-wing-structural-fatigue-limitation/analysis","conflicts":"/api/acts/ad-mu-2-5-amdt-3-wing-structural-fatigue-limitation/conflicts","importantCases":"/api/acts/ad-mu-2-5-amdt-3-wing-structural-fatigue-limitation/important-cases","documents":"/api/acts/ad-mu-2-5-amdt-3-wing-structural-fatigue-limitation/documents"}}