{"id":"F2006B10718","name":"AD/HU 369/55 - Main Gear Box Ring Gear Carrier Shaft - Inspection","slug":"ad-hu-369-55-main-gear-box-ring-gear-carrier-shaft-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116698,"registerId":"commonwealth-F2006B10718-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HU 369/55 - Main Gear Box Ring Gear Carrier Shaft - Inspection","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)  \nMcDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters\n\nAD/HU 369/55 Main Gear Box Ring Gear Carrier Shaft \\- Inspection\n\n  \n11/82\n\nApplicability: All model 369D series helicopters fitted with main transmission P/N 369D25100 \\- Basic Configuration.\n\nNote: Transmissions with a letter “U” prefix to the serial number on the transmission ID plate, or transmissions P/N 369D25100-501 and later suffix number configurations are not affected by this Directive.\n\nDocument: Hughes SIN No. DN-105.\n\nNote: FAA AD 82-17-01 refers.\n\nCompliance: Inspect in accordance with Part 1 of the document within 100 hours time in service after 30 November 1982, and thereafter at periods not exceeding 300 hours time in service. Inspections in accordance with Part 1 may be discontinued subsequent to inspection in accordance with Part II of the document.\n\nBackground: Cracks have been found in the electron beam welded junction of the lower disc of the ring gear carrier and the output shaft of the main gear box.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive from 1982 addressing a specific mechanical defect in a specific helicopter model. It has not expanded beyond its original purpose of mandating inspections for cracked welds in the main gear box shaft."},"complexity_factors":["Single, specific mechanical component addressed (main gear box ring gear carrier shaft)","Only one applicability criterion with a clear exclusion note","Simple two-part compliance structure (initial inspection + recurring interval)","No defined terms section or interpretation provisions","No cross-references to other legislation beyond a single FAA AD reference","Background is one sentence explaining the safety rationale","Total length is approximately 150 words"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspections of the main gear box ring gear carrier shaft on McDonnell Douglas (Hughes) / Kawasaki 369D helicopters fitted with transmission P/N 369D25100 (excluding units with a \"U\" prefix or later P/Ns).  \n\nCracks were found in the electron‑beam welded joint; failure could cause total rotor power loss. First inspection is within 100 flight hours after 30 Nov 1982, then every 300 hours, with Part II inspection substituting ongoing Part I checks."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Based solely on the directive text, the scope is limited to 369D series helicopters with transmission P/N 369D25100 (basic configuration) and explicitly excludes transmissions with a 'U' serial‑prefix or P/N 369D25100‑501 and later. The instrument defines inspections and an exception pathway (Part II ending Part I checks) but does not expand applicability beyond those stated limits."},"complexity_factors":["Narrow technical focus on a specific gearbox component and P/N (Applicability)","Clear, fixed inspection schedule with initial and recurring intervals (Compliance)","Dependency on an external manufacturer document (Hughes SIN DN‑105) for inspection procedure (Document)","Limited applicability with specific exclusions (\"U\" prefix; P/N -501 and later) requiring checks of transmission identification (Applicability)","Cross‑reference to an FAA AD increases traceability requirements but not procedural complexity (Note)"],"plain_english_summary":"This airworthiness directive requires owners/operators of McDonnell Douglas (Hughes) and Kawasaki 369D helicopters fitted with main transmission P/N 369D25100 to have the main gearbox ring‑gear carrier shaft inspected because cracks were found in the welded junction (Background; Applicability). It excludes transmissions with a “U” serial‑prefix or P/N 369D25100‑501 and later. Inspections must follow Hughes Service Information Notice DN‑105 and be done within 100 hours TIS after 30 Nov 1982 and thereafter at intervals not exceeding 300 hours (Document; Compliance)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-369-55-main-gear-box-ring-gear-carrier-shaft-inspection","history":"/api/acts/ad-hu-369-55-main-gear-box-ring-gear-carrier-shaft-inspection/history","analysis":"/api/acts/ad-hu-369-55-main-gear-box-ring-gear-carrier-shaft-inspection/analysis","conflicts":"/api/acts/ad-hu-369-55-main-gear-box-ring-gear-carrier-shaft-inspection/conflicts","importantCases":"/api/acts/ad-hu-369-55-main-gear-box-ring-gear-carrier-shaft-inspection/important-cases","documents":"/api/acts/ad-hu-369-55-main-gear-box-ring-gear-carrier-shaft-inspection/documents"}}