{"id":"F2006B04702","name":"AD/BELL 47/79 Amdt 1 - Tail Rotor Gearbox","slug":"ad-bell-47-79-amdt-1-tail-rotor-gearbox","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44466,"registerId":"commonwealth-F2006B04702-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 47/79 Amdt 1 - Tail Rotor Gearbox","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)  Bell Helicopter Textron 47 (All Variants) Series Helicopters\n\n \n\nAD/BELL 47/79\n\nAmdt 1\n\n\nTail Rotor Gearbox 10/86\n\n \n\nApplicability: All models fitted with P/N 47-640-075-1 or -7 tail rotor gear boxes. Document:  Bell SB 47-77-1. Kawasaki-Bell SB KSB-Bell 345.\n\nCompliance: Within 100 hours time in service after 30 April 1977.\n\n \n\nBackground: To assure the latest type bearing is installed and the input shaft is of correct dimensions. This Directive has been amended to include Kawasaki-Bell Helicopters.\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":1786},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":true,"description":"The amendment expanded coverage from original Bell Helicopter Textron models to also include Kawasaki-Bell manufactured helicopters, broadening the scope to cover licensed variants of the aircraft type."},"complexity_factors":["Very short document with single compliance action","Limited applicability (only two specific part numbers)","Simple time-based compliance trigger (100 hours after fixed date)","Relies on external service bulletins for technical details rather than embedding complex specifications"],"plain_english_summary":"This Airworthiness Directive (AD) is a mandatory safety order for owners and operators of **Bell 47 series helicopters**. It requires specific inspections and potential replacements of the **tail rotor gearbox** on aircraft fitted with part numbers 47-640-075-1 or -7.\n\n**What must be done:**\n- Ensure the tail rotor gearbox contains the latest specification bearings\n- Verify the input shaft dimensions meet manufacturing specifications  \n- Complete these checks within 100 hours of flight time after 30 April 1977\n\n**Why it matters:**\nThe tail rotor is critical for helicopter directional control. Faulty bearings or incorrectly sized shafts in the gearbox could cause catastrophic mechanical failure, leading to loss of control and potential accidents.\n\n**Who is affected:**\nOperators of all Bell 47 variants with the specified gearbox part numbers, including Kawasaki-Bell manufactured models (which were added to the original directive in this amendment)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-47-79-amdt-1-tail-rotor-gearbox","history":"/api/acts/ad-bell-47-79-amdt-1-tail-rotor-gearbox/history","analysis":"/api/acts/ad-bell-47-79-amdt-1-tail-rotor-gearbox/analysis","conflicts":"/api/acts/ad-bell-47-79-amdt-1-tail-rotor-gearbox/conflicts","importantCases":"/api/acts/ad-bell-47-79-amdt-1-tail-rotor-gearbox/important-cases","documents":"/api/acts/ad-bell-47-79-amdt-1-tail-rotor-gearbox/documents"}}