{"id":"F2006B04488","name":"AD/BELL 206/31 - Main Transmission - Modification","slug":"ad-bell-206-31-main-transmission-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44325,"registerId":"commonwealth-F2006B04488-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 206/31 - Main Transmission - Modification","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 Canada (BHTC) 206 and Agusta Bell 206 Series Helicopters\n\n \n\nAD/BELL 206/31 Main Transmission - Modification 2/71\n\nApplicability: All models with transmission P/N 206-040-002-5 not incorporating the five modifications described in SL 206A-159.\n\n \n\nDocument: Bell SB No. 206A-17, Part II.\n\n \n\nCompliance: Before installation in an aircraft following next overhaul completed after 31 December 1970.\n\n \n\nBackground: AD/Agusta 206/22 equivalent.\n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2019},"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"This is a discrete technical safety directive targeting a specific mechanical component on specific helicopter models. It has not expanded beyond its original purpose of mandating a transmission modification."},"complexity_factors":["Single operative provision with clear deadline","Limited to one specific part number","No defined terms section","No internal cross-references to other legislative provisions","Binary applicability test (incorporating the five modifications or not)"],"plain_english_summary":"**What this does:** This directive requires owners of specific Bell 206 helicopters to modify the main transmission gearbox before reinstalling it in an aircraft.\n\n**Who it affects:** Operators of Bell 206 and Agusta Bell 206 helicopters that have a main transmission with part number 206-040-002-5, unless the transmission already incorporates five specific modifications listed in Bell Service Letter 206A-159.\n\n**What you must do:** Before putting the transmission back into an aircraft after its next overhaul (completed after 31 December 1970), you must carry out the modification described in Bell Service Bulletin 206A-17, Part II.\n\n**Why it matters:** This ensures a critical safety update is applied to the helicopter's main transmission to prevent mechanical failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-206-31-main-transmission-modification","history":"/api/acts/ad-bell-206-31-main-transmission-modification/history","analysis":"/api/acts/ad-bell-206-31-main-transmission-modification/analysis","conflicts":"/api/acts/ad-bell-206-31-main-transmission-modification/conflicts","importantCases":"/api/acts/ad-bell-206-31-main-transmission-modification/important-cases","documents":"/api/acts/ad-bell-206-31-main-transmission-modification/documents"}}