{"id":"F2006B04484","name":"AD/BELL 206/28 - Engine Bell Mouth Seal Doubler - Modification","slug":"ad-bell-206-28-engine-bell-mouth-seal-doubler-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44321,"registerId":"commonwealth-F2006B04484-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 206/28 - Engine Bell Mouth Seal Doubler - 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 206/28 Engine Bell Mouth Seal Doubler - Modification 9/70\n\nApplicability: All model AB-206A and 206A with S/Nos. 1 to 499. Document:  Bell SL 206A-152.\n\nCompliance: Within 100 hours time in service after 30 September 1970. Background: AD/Agusta 206/20 equivalent.\n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":2137},"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"The directive maintains its original narrow scope as a targeted safety modification for early production models of the Bell 206 helicopter series. It addresses a specific technical airworthiness issue without expansion into broader operational or maintenance requirements."},"complexity_factors":["Single, unambiguous modification requirement","Narrow applicability limited to specific serial number range (S/Nos. 1-499)","Simple compliance calculation (100 hours time in service after fixed date)","No exceptions, exemptions, or conditional logic","Only one external technical reference (Bell SL 206A-152)"],"plain_english_summary":"This is a mandatory safety directive (called an **Airworthiness Directive**) issued by the Civil Aviation Safety Authority (CASA) that requires a specific mechanical fix for certain Bell helicopters.\n\n**What it requires:**\nOwners and operators must modify the **engine bell mouth seal doubler** — a reinforcement component around the engine's air intake — on affected helicopters. The work must be carried out exactly as described in Bell Service Letter 206A-152.\n\n**Who is affected:**\nAnyone operating Bell helicopter models **AB-206A and 206A** with serial numbers **1 through 499**.\n\n**Compliance deadline:**\nThe modification must be completed within **100 hours of flight time** (actual flying hours, not calendar time) after 30 September 1970.\n\n**Why it matters:**\nAirworthiness Directives are legally binding. This modification addresses a specific safety defect in the engine intake area of these early-production helicopters. Operating the aircraft without completing this modification makes it unairworthy and illegal to fly."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-206-28-engine-bell-mouth-seal-doubler-modification","history":"/api/acts/ad-bell-206-28-engine-bell-mouth-seal-doubler-modification/history","analysis":"/api/acts/ad-bell-206-28-engine-bell-mouth-seal-doubler-modification/analysis","conflicts":"/api/acts/ad-bell-206-28-engine-bell-mouth-seal-doubler-modification/conflicts","importantCases":"/api/acts/ad-bell-206-28-engine-bell-mouth-seal-doubler-modification/important-cases","documents":"/api/acts/ad-bell-206-28-engine-bell-mouth-seal-doubler-modification/documents"}}