{"id":"F2006B10762","name":"AD/HU 369/98 - Input Shaft Coupling - Inspection","slug":"ad-hu-369-98-input-shaft-coupling-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56211,"registerId":"commonwealth-F2006B10762-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HU 369/98 - Input Shaft Coupling - 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 369/98 Input Shaft Coupling \\- Inspection 5/99\n\nApplicability: All McDonnell Douglas Helicopter System (MDHS) model 369D, 369E, 369FF, 369H, MD500N and MD600N helicopters, with input shaft coupling assemblies part number (P/N) 369F5133-1, serial number (S/N) 030829-0126 through 030829-0207, installed on main transmission, P/N 369F5100-503, and on overrunning clutch P/N 369F5450.\n\nRequirement: 1. Visually inspect the coupling assemblies P/N 369F5133-1, installed on main transmission P/N 369F5100-503, and on overrunning clutch P/N 369F5450, for pitting under the solid film lubricant in the spline area of the coupling. Boeing Service Bulletins SB369H-240, SB369E-085, SB500N-013, SB369D-192,\n\nSB369F-072 and SB600N-003 dated 26 September 1997 refer.\n\n2. Replace the coupling assembly with an airworthy coupling assembly P/N 369F5133-1 that has been inspected as required by paragraph (1) above.\n\nNote: US FAA 99-04-12 Amendment 39-11036 refers.\n\nCompliance: 1. Within 100 hrs time in service of the effective date of this Directive.\n\n2. Before next flight if pitting is detected at the inspection at requirement 1 above. This Airworthiness Directive becomes effective on 20 May 1999.\n\nBackground: Three operators reports of pitting on the internal spline teeth of the input shaft coupling led to the issue of a US FAA AD to inspect the shaft coupling. Existence of the pitting could lead to failure of the spline teeth in the input shaft coupling assembly, loss of drive to the main rotor system and subsequent loss of control of the helicopter.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive confines its effect to specified helicopter models and a narrow set of coupling part and serial numbers; it requires inspection and, if necessary, replacement. It does not expand beyond the identified components or models and aligns with the referenced US FAA AD and Boeing service bulletins, so the scope remains targeted to the originally identified hardware and failure mode."},"complexity_factors":["Narrow parts and serial-number scope: applies only to coupling P/N 369F5133-1, S/N 030829-0126 through 030829-0207, on listed helicopter models (Applicability).","Operational timing constraint: inspection must be completed within 100 flight hours of the directive’s effective date (Compliance 1), creating a medium-term scheduling load for operators.","Immediate grounding risk: detected pitting requires replacement before next flight (Requirement 2; Compliance 2), which can cause immediate operational disruption.","Inspection difficulty: visual inspection under solid film lubricant in spline area may require cleaning or disassembly to reliably detect pitting (Requirement 1).","Replacement logistics and cost: operators must obtain an airworthy coupling that has been inspected as required (Requirement 2), imposing parts-procurement and labour costs on operators.","Cross-references to multiple service bulletins and FAA AD: implementation depends on following Boeing service bulletins and the referenced US FAA AD, adding procedural reference complexity (Requirement 1; Note).","Safety consequence linkage: Background ties pitting to possible spline failure and loss of main-rotor drive, which justifies the urgent remedial action but raises risk-aversion enforcement (Background).","Enforcement clarity: requirements are prescriptive (inspect, replace) with limited administrative discretion—operators decide scheduling and logistics, regulator enforces compliance."],"plain_english_summary":"This Airworthiness Directive requires operators of specified McDonnell Douglas/Kawasaki 369, MD500N and MD600N helicopters fitted with certain input shaft coupling assemblies (P/N 369F5133-1, S/N 030829‑0126–0207) to visually inspect the coupling spline area for pitting and to replace any affected coupling. Inspection must occur within 100 flight hours; if pitting is found the coupling must be replaced before the next flight. The directive targets a failure mode that can interrupt main‑rotor drive."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope as a targeted safety inspection order for a specific mechanical defect in specific helicopter models. It has not expanded beyond its original purpose of addressing the pitting issue in input shaft couplings."},"complexity_factors":["Single, specific mechanical component targeted (input shaft coupling)","Narrow applicability limited to 6 specific helicopter models with specific part and serial number ranges","Two straightforward requirements: visual inspection and conditional replacement","No nested exceptions or complex conditional logic","Clear compliance timeline (100 hours or before next flight)","Only 3 defined technical references (part numbers) in the applicability section","Background provides clear rationale without legal cross-referencing"],"plain_english_summary":"This safety order requires owners/operators of certain McDonnell Douglas/Kawasaki helicopters (MD 369D/E/FF/H, MD500N, MD600N) fitted with input shaft coupling P/N 369F5133-1 (SN 030829-0126 through -0207) to inspect the coupling’s spline for pitting and replace it if found.  \n\nIt’s urgent—inspections within 100 flight hours—because pitting can cause spline failure, loss of main-rotor drive, and loss of control; the action follows multiple incidents and an FAA directive."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-369-98-input-shaft-coupling-inspection","history":"/api/acts/ad-hu-369-98-input-shaft-coupling-inspection/history","analysis":"/api/acts/ad-hu-369-98-input-shaft-coupling-inspection/analysis","conflicts":"/api/acts/ad-hu-369-98-input-shaft-coupling-inspection/conflicts","importantCases":"/api/acts/ad-hu-369-98-input-shaft-coupling-inspection/important-cases","documents":"/api/acts/ad-hu-369-98-input-shaft-coupling-inspection/documents"}}