{"id":"F2006B11393","name":"AD/MU-2/63 - Landing Gear Drive Train","slug":"ad-mu-2-63-landing-gear-drive-train","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":57294,"registerId":"commonwealth-F2006B11393-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/MU-2/63 - Landing Gear Drive Train","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)  \nMitsubishi MU-2 Series Aeroplanes\n\n![](image.002.png)11/98\n\nRequirement: 1. Inspect the torque shaft (part number 030A-38605-21) for correct spline connection in accordance with paragraph 4 of Mitsubishi Heavy Industry MU-2 Service Bulletin (SB) 235, dated 4 August 1998.\n\n2. If the distance measured in the Requirement 1 inspection is less than 12mm, before further flight, replace or modify the torque shaft assembly in accordance with paragraph 5 of SB 235.\n\nNote: JCAB AD TCD-4838-98 refers.\n\nCompliance: Unless already accomplished, within 100 hours time in service after 8 October 1998.\n\nThis airworthiness directive becomes effective on 8 October 1998.\n\nBackground: This Directive is to prevent disconnection within the landing gear drive train, which could result in a situation with the nose gear extended and the main gear retracted.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope aligns with the stated purpose in the Background: it targets a specific torque shaft spline connection to prevent a landing gear drive-train disconnection that could leave the nose gear extended and main gear retracted. The AD requires inspection and, where the measured clearance is under 12 mm, replacement or modification per SB 235, within the specified 100-hour compliance window. There is no indication in the directive text that the scope departs from that original stated intent (Background; Requirement 1; Requirement 2; Compliance)."},"complexity_factors":["Single-component focus: directive applies to one specific part number (030A-38605-21), reducing scope complexity (Requirement 1).","Numeric threshold: a precise measurement (less than 12 mm) creates a clear pass/fail test but requires accurate measurement equipment and technique (Requirement 1; Requirement 2).","Reliance on external procedural document: inspection and corrective action follow manufacturer’s Service Bulletin SB 235, so implementers must obtain and apply that bulletin (Requirement 1; Requirement 2).","Limited compliance window and strict operational constraint: mandated within 100 hours time in service and ‘before further flight’ requirement for failed measurements creates scheduling and operational constraints (Compliance; Requirement 2).","Low regulatory discretion in outcome: the AD prescribes inspection and corrective options without broad case-by-case waivers in the text, simplifying regulatory decision-making (Requirement 1; Requirement 2)."],"plain_english_summary":"This directive requires Mitsubishi MU-2 owners/operators to inspect a specific landing‑gear torque shaft (P/N 030A-38605-21) for spline clearance per Mitsubishi SB 235 and, if the distance is under 12 mm, to replace or modify the assembly before further flight. Compliance is due within 100 flight hours of 8 Oct 1998 and costs fall to the owner. The measure aims to prevent a landing‑gear drive‑train disconnection that could leave the nose gear extended and main gear retracted."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive (AD) — a targeted safety instrument addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original purpose of preventing landing gear drive train disconnection."},"complexity_factors":["Single, specific aircraft type (Mitsubishi MU-2 series)","Only 2 substantive requirements (inspect; replace if condition met)","Single defined measurement threshold (12mm)","No nested exceptions or conditional logic beyond the basic if/then structure","Short document (approximately 150 words of operative text)","References only one external technical document (Service Bulletin 235)","Clear compliance deadline with simple time-in-service calculation"],"plain_english_summary":"This is a **safety order for a specific aircraft model** — the Mitsubishi MU-2 series aeroplanes.\n\n**What it does:**\nThe Civil Aviation Safety Authority (CASA) is requiring owners and operators of these planes to inspect a specific mechanical part called the **torque shaft** (part number 030A-38605-21). This part is part of the landing gear system — the machinery that extends and retracts the wheels.\n\n**The problem:**\nIf the torque shaft isn't connected properly, the landing gear could malfunction in a dangerous way: the nose wheel could stay down while the main wheels tuck up into the fuselage. This \"split\" landing gear configuration would make landing extremely hazardous.\n\n**What must be done:**\n- **Inspect** the torque shaft connection following Mitsubishi's official Service Bulletin 235 (dated 4 August 1998)\n- **If the connection is too short** (less than 12mm), the shaft must be **replaced or modified** before the plane flies again\n- **Deadline:** Complete this within 100 hours of flying time after 8 October 1998 (unless already done)\n\n**Who it affects:**\nOwners, operators, and maintenance engineers of Mitsubishi MU-2 aircraft registered in Australia.\n\n**Why it matters:**\nThis prevents a potentially catastrophic landing gear failure that could cause loss of control during landing."}},"importantCases":[],"_links":{"self":"/api/acts/ad-mu-2-63-landing-gear-drive-train","history":"/api/acts/ad-mu-2-63-landing-gear-drive-train/history","analysis":"/api/acts/ad-mu-2-63-landing-gear-drive-train/analysis","conflicts":"/api/acts/ad-mu-2-63-landing-gear-drive-train/conflicts","importantCases":"/api/acts/ad-mu-2-63-landing-gear-drive-train/important-cases","documents":"/api/acts/ad-mu-2-63-landing-gear-drive-train/documents"}}