{"id":"F2006B10741","name":"AD/HU 369/77 - Main and Tail Rotor Control Tubes","slug":"ad-hu-369-77-main-and-tail-rotor-control-tubes","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116743,"registerId":"commonwealth-F2006B10741-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HU 369/77 - Main and Tail Rotor Control Tubes","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 369/77 Main and Tail Rotor Control Tubes 9/89\n\nDM\n\n \n\nApplicability: All model 369 series helicopters.\n\n \n\nRequirement: Action in accordance with McDonnell Douglas SIN No HN-217, DN-158, EN-48 or FN-36, as applicable.\n\n \n\nCompliance: Part 1 of Requirement Document: Unless already accomplished, within 25 flight hours from 14 July 1989.\n\n \n\nPart 2 of Requirement Document: At next inspection for issue of a Maintenance Release but not later than 31 December 1989.\n\n \n\nBackground:  The manufacturer advises that cracking of the main and tail rotor control tubes, mounted in the vertical tunnel, has been discovered.\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 discrete, time-bound safety directive addressing a specific manufacturing defect. It has not expanded beyond its original purpose of mandating inspection and repair of cracked rotor control tubes."},"complexity_factors":["Single-issue directive with one specific mechanical fault","Only 4 defined compliance paths (the four SIN numbers)","Simple two-part compliance schedule with clear deadlines","No nested exceptions or conditional logic","No cross-references to other legislation beyond the Civil Aviation Regulations 1998 Part 39 framework","Background section provides clear rationale without legal caveats"],"plain_english_summary":"**What this is:** An Airworthiness Directive (AD) — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) telling helicopter operators they must fix a specific mechanical problem.\n\n**What it does:** Orders owners and operators of McDonnell Douglas (Hughes) and Kawasaki 369 series helicopters to inspect and repair cracks found in the main and tail rotor control tubes. These tubes run through the vertical tunnel of the helicopter and are critical for controlling the aircraft.\n\n**Who it affects:** Anyone who owns, operates, or maintains any model in the 369 series helicopter fleet (these are light utility helicopters, sometimes called the Hughes 500 series).\n\n**What must be done:**\n- **Part 1:** If not already done, complete the first set of repairs within 25 flight hours after 14 July 1989.\n- **Part 2:** Complete the second set of repairs by the next scheduled maintenance check, but definitely before 31 December 1989.\n\n**Why it matters:** Cracked control tubes can lead to loss of control of the main or tail rotor — which means the pilot could lose the ability to steer or stabilize the helicopter. This is a \"fix it now or ground the aircraft\" safety order.\n\n**The paperwork:** Operators must follow specific manufacturer service instructions (SIN HN-217, DN-158, EN-48, or FN-36 depending on which helicopter model they have)."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD text consistently identifies the problem (cracking of main and tail rotor control tubes), the affected fleet (all model 369 series helicopters), and the corrective action mechanism (follow specified McDonnell Douglas SINs) along with two compliance deadlines. The document contains no material that indicates the scope has been widened or narrowed relative to its own stated purpose; there is no language in the text showing a change from the instrument's apparent original intent."},"complexity_factors":["References multiple external manufacturer Service Instruction Notices (SIN No HN-217, DN-158, EN-48 or FN-36) rather than including technical detail (Requirement).","Two distinct compliance obligations with different triggers and deadlines (25 flight hours from 14 July 1989; at next Maintenance Release inspection but not later than 31 December 1989) (Compliance).","Broad fleet-wide applicability (all model 369 series helicopters) requiring operators across the fleet to determine applicability to their aircraft (Applicability).","Technical content and exact remedial steps are not in the AD text, requiring operators to obtain and interpret separate documents (Requirement).","No procedural text in the AD about alternatives, exemptions, or who bears cost, leaving those practical matters unresolved in the instrument (AD text generally)."],"plain_english_summary":"This AD requires all operators/owners of McDonnell Douglas (Hughes) and Kawasaki 369 series helicopters to perform the inspections and corrective work specified in the manufacturer’s Service Instruction Notices to address discovered cracking in main and tail rotor control tubes.\n\nIt imposes an immediate short-term action and a second action at the next maintenance-release inspection, with a final deadline of 31 December 1989."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-369-77-main-and-tail-rotor-control-tubes","history":"/api/acts/ad-hu-369-77-main-and-tail-rotor-control-tubes/history","analysis":"/api/acts/ad-hu-369-77-main-and-tail-rotor-control-tubes/analysis","conflicts":"/api/acts/ad-hu-369-77-main-and-tail-rotor-control-tubes/conflicts","importantCases":"/api/acts/ad-hu-369-77-main-and-tail-rotor-control-tubes/important-cases","documents":"/api/acts/ad-hu-369-77-main-and-tail-rotor-control-tubes/documents"}}