{"id":"F2006B11367","name":"AD/MU-2/37 - Flap Flexible Shaft Sealing and Torque Check","slug":"ad-mu-2-37-flap-flexible-shaft-sealing-and-torque-check","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":57266,"registerId":"commonwealth-F2006B11367-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/MU-2/37 - Flap Flexible Shaft Sealing and Torque Check","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-2/37 Flap Flexible Shaft Sealing and Torque Check 12/85\n\nApplicability: All models MU-2B/-10/-15/-20/-25/-26 with S/Nos. 008 to 347 except S/Nos. 313 and 321. All models MU-2B-30/-35/- 36 with S/Nos.501 to 696 except S/Nos. 652\n\nand 661.\n\n \n\nRequirement: Action in accordance with Mitsubishi SB No. 198.\n\n \n\nNote: JCAB AD No. TCD-2451-85 refers.\n\n \n\nCompliance: At the next scheduled inspection for Maintenance Release issue after 31 December 1985.\n\n \n\nBackground: The manufacturer reports failures of the flexible drive shaft attributable to ingress of moisture.\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":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD's scope aligns with the stated purpose in the Background: to address flexible drive shaft failures caused by moisture ingress. It limits corrective requirements to specific MU-2 models and serial numbers and prescribes compliance by following Mitsubishi Service Bulletin No. 198 at the next scheduled Maintenance Release after 31 December 1985, which is consistent with the instrument’s stated objective (Background; Applicability; Requirement; Compliance)."},"complexity_factors":["Narrow applicability by model and serial number increases administrative steps to identify affected aircraft (Applicability).","The AD delegates technical detail to an external document (Mitsubishi Service Bulletin No. 198), so implementers must obtain and interpret that SB (Requirement).","Compliance timing is tied to the next scheduled Maintenance Release after a fixed date, which interacts with operators' maintenance schedules and can create variability in when actions occur (Compliance).","The AD does not include the step‑by‑step technical remedy within the directive, producing reliance on manufacturer instructions and on maintenance providers' interpretation (Requirement).","Reference to an external foreign authority AD (JCAB AD No. TCD-2451-85) adds cross-jurisdictional traceability but no additional procedural detail (Note)."],"plain_english_summary":"This Airworthiness Directive requires owners/operators of specified Mitsubishi MU-2 serial-numbered aeroplanes to have the flap flexible drive shaft sealed and its torque checked by following Mitsubishi Service Bulletin No. 198. Actions must be done at the next scheduled Maintenance Release after 31 December 1985. It affects aircraft operators and maintenance personnel, was issued because moisture ingress caused shaft failures, and imposes compliance costs (inspection, sealing, torque checks and any repairs) on the owner/operator."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive addressing a specific safety defect in a specific aircraft type. It has not expanded beyond its original purpose of addressing flexible drive shaft moisture ingress."},"complexity_factors":["Single, specific mechanical requirement (sealing and torque check)","Clear applicability section with explicit serial number ranges and exceptions","Single cross-reference to manufacturer service bulletin","No defined terms section","No nested conditional logic or exceptions beyond the serial number exclusions","Approximately 150 words of substantive content"],"plain_english_summary":"**What this is:** This is an Airworthiness Directive (AD) — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific Mitsubishi MU-2 aircraft.\n\n**What it does:** It requires owners and operators of certain Mitsubishi MU-2 aeroplanes to inspect and seal the flexible drive shaft that controls the flaps (the movable surfaces on the wings that help the plane slow down for landing). They must also check that the shaft is tightened to the correct torque (tightness specification).\n\n**Who it affects:** Owners and operators of Mitsubishi MU-2B, MU-2B-10, -15, -20, -25, -26, -30, -35, and -36 models with specific serial numbers. Some serial numbers are excluded — check the applicability list carefully.\n\n**Why it matters:** The manufacturer reported that moisture was getting into the flexible drive shaft and causing it to fail. If this shaft fails, the pilot might lose control of the flaps, which could make landing dangerous. This directive prevents that failure by requiring sealing and torque checks.\n\n**When to comply:** By the next scheduled inspection for issuing a Maintenance Release (a document certifying the aircraft is safe to fly) after 31 December 1985.\n\n**How to comply:** Follow the instructions in Mitsubishi Service Bulletin No. 198. The Japanese aviation authority (JCAB) has issued a similar directive (TCD-2451-85) for reference."}},"importantCases":[],"_links":{"self":"/api/acts/ad-mu-2-37-flap-flexible-shaft-sealing-and-torque-check","history":"/api/acts/ad-mu-2-37-flap-flexible-shaft-sealing-and-torque-check/history","analysis":"/api/acts/ad-mu-2-37-flap-flexible-shaft-sealing-and-torque-check/analysis","conflicts":"/api/acts/ad-mu-2-37-flap-flexible-shaft-sealing-and-torque-check/conflicts","importantCases":"/api/acts/ad-mu-2-37-flap-flexible-shaft-sealing-and-torque-check/important-cases","documents":"/api/acts/ad-mu-2-37-flap-flexible-shaft-sealing-and-torque-check/documents"}}