{"id":"F2006B10683","name":"AD/HU 369/2 Amdt 1 - Tail Rotor Gearbox - Inspection and/or Replacement","slug":"ad-hu-369-2-amdt-1-tail-rotor-gearbox-inspection-and-or-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116630,"registerId":"commonwealth-F2006B10683-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HU 369/2 Amdt 1 - Tail Rotor Gearbox - Inspection and/or Replacement","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)  McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters\n\n \n\nAD/HU 369/2\n\nAmdt 1\n\n\nTail Rotor Gearbox - Inspection and/or Replacement\n\n\n6/70\n\n \n\nApplicability: All models fitted with tail rotor gearbox P/N 369A5400 with gearbox S/Nos. listed in Hughes SIN No. HN-1.1 and Addendum.\n\n \n\nDocument: Hughes SIN No. HN-1.1 and addendum XI.\n\n \n\nCompliance: Before achieving 90 hours component total time in service, after 1 September 1971.\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\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a narrow, targeted safety directive focused on a specific mechanical component in a specific aircraft series. The amendment appears to maintain the original scope (tail rotor gearbox inspection/replacement) without expansion into unrelated systems or aircraft types."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 3 operative requirements: applicability, reference document, and compliance deadline","Single cross-reference to external technical document (Hughes SIN HN-1.1)","No defined terms section — relies on standard aviation terminology","No conditional logic or nested exceptions","Straightforward temporal compliance trigger (90 hours time-in-service)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific helicopters.\n\n**What it does:**\n- Requires owners and operators of certain McDonnell Douglas (Hughes) and Kawasaki 369 series helicopters to **inspect or replace the tail rotor gearbox** — a critical component that transfers power to the tail rotor (which keeps the helicopter stable and prevents it from spinning).\n\n**Who it affects:**\n- All Hughes/Kawasaki 369 helicopters fitted with a specific tail rotor gearbox part number (369A5400) and specific serial numbers listed in a Hughes service bulletin (SIN HN-1.1).\n\n**What must be done:**\n- Before the gearbox reaches **90 hours of total flight time** (counted from when it entered service), operators must follow the inspection or replacement instructions in Hughes Service Information Notice HN-1.1 and its Addendum XI.\n\n**Why it matters:**\n- Tail rotor gearbox failures can cause catastrophic loss of control. This directive prevents accidents by catching potential defects early in the component's life. The deadline (before 90 hours) suggests this addresses a known manufacturing or design defect that tends to appear early in operation.\n\n**Key detail:** The compliance deadline was **1 September 1971** — this is a historical directive from the early 1970s, though it remains on the books as Amendment 1."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"The instrument is presented as Amendment 1 to AD/HU 369/2, which indicates a change was made from the original AD. The provided text, however, contains only the amended directive language (Applicability; Document; Compliance) and does not include the original AD text or a comparison, so the exact nature of the change from the original wording or scope cannot be determined from the supplied material."},"complexity_factors":["Narrow technical scope: applies only to tail rotor gearbox P/N 369A5400 with serial numbers listed in Hughes SIN No. HN-1.1 and addendum (Applicability; Document).","Clear, single compliance deadline tied to component hours (before 90 hours total time in service) (Compliance).","Dependence on an external manufacturer document (Hughes SIN No. HN-1.1 and addendum) for identification of affected serial numbers and likely procedures (Document).","Requirement creates administrative tasks for operators: identify serial numbers, track component hours, schedule inspections/replacements (Applicability; Compliance).","Temporal reference to operations after a historical date (after 1 September 1971) which may complicate record-checking for older components (Compliance)."],"plain_english_summary":"This airworthiness directive requires owners/operators of McDonnell Douglas (Hughes) and Kawasaki 369 series helicopters to inspect and/or replace tail rotor gearboxes P/N 369A5400 with serial numbers listed in Hughes SIN No. HN‑1.1 (and addendum) before the gearbox reaches 90 hours total time in service. It matters because it forces operators to check serial numbers, track component hours, consult the manufacturer’s SIN for procedures, and bear inspection/replacement costs and aircraft downtime to meet the compliance deadline."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-369-2-amdt-1-tail-rotor-gearbox-inspection-and-or-replacement","history":"/api/acts/ad-hu-369-2-amdt-1-tail-rotor-gearbox-inspection-and-or-replacement/history","analysis":"/api/acts/ad-hu-369-2-amdt-1-tail-rotor-gearbox-inspection-and-or-replacement/analysis","conflicts":"/api/acts/ad-hu-369-2-amdt-1-tail-rotor-gearbox-inspection-and-or-replacement/conflicts","importantCases":"/api/acts/ad-hu-369-2-amdt-1-tail-rotor-gearbox-inspection-and-or-replacement/important-cases","documents":"/api/acts/ad-hu-369-2-amdt-1-tail-rotor-gearbox-inspection-and-or-replacement/documents"}}