{"id":"F2006B10702","name":"AD/HU 369/40 - Tail Rotor Fork Hinge Nut - Replacement","slug":"ad-hu-369-40-tail-rotor-fork-hinge-nut-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116668,"registerId":"commonwealth-F2006B10702-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HU 369/40 - Tail Rotor Fork Hinge Nut - 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 369/40 Tail Rotor Fork Hinge Nut - Replacement 8/79\n\nApplicability: All model 369H, 369HS, 369HM and 369HE helicopters. Model 369D helicopters with S/Nos. 0003D to 0384D.\n\n \n\nDocument: As applicable: Hughes SIN HN-131, or SIN DN-33. Compliance:  Within 100 hours time in service after 31 August 1979.\n\nBackground:  To reduce the possibility of stress corrosion cracking, a corrosion resistant nut is introduced for the tail rotor fork hinge bolt.\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":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1481},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive maintains its original narrow scope of requiring specific hardware replacement on affected helicopter models to address a known safety defect."},"complexity_factors":["Single discrete maintenance action with no conditional exceptions","Limited applicability to specific aircraft models and serial number ranges only","Clear compliance deadline based on flight hours (time in service)","No cross-references to other legislation beyond manufacturer service bulletins","Straightforward safety objective with minimal technical jargon"],"plain_english_summary":"**What this directive does:** This Airworthiness Directive (a mandatory safety order) requires operators of specific Hughes and Kawasaki 369 series helicopters to replace the nuts on their tail rotor fork hinge bolts.\n\n**Who it affects:** Owners and operators of:\n- Model 369H, 369HS, 369HM, and 369HE helicopters (all serial numbers)\n- Model 369D helicopters with serial numbers 0003D through 0384D\n\n**What must be done:** Replace the existing tail rotor fork hinge nuts with new corrosion-resistant nuts to prevent stress corrosion cracking (a type of metal fatigue caused by combined corrosion and mechanical stress that can lead to sudden failure).\n\n**When:** The replacement must be completed within 100 hours of flight time after 31 August 1979.\n\n**Why it matters:** Stress corrosion cracking in this component could lead to tail rotor failure and loss of control of the helicopter. This directive mandates a hardware upgrade to prevent potentially catastrophic accidents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-369-40-tail-rotor-fork-hinge-nut-replacement","history":"/api/acts/ad-hu-369-40-tail-rotor-fork-hinge-nut-replacement/history","analysis":"/api/acts/ad-hu-369-40-tail-rotor-fork-hinge-nut-replacement/analysis","conflicts":"/api/acts/ad-hu-369-40-tail-rotor-fork-hinge-nut-replacement/conflicts","importantCases":"/api/acts/ad-hu-369-40-tail-rotor-fork-hinge-nut-replacement/important-cases","documents":"/api/acts/ad-hu-369-40-tail-rotor-fork-hinge-nut-replacement/documents"}}