{"id":"F2006B09110","name":"AD/DHC-6/23 - Inverter Fuses - Replacement","slug":"ad-dhc-6-23-inverter-fuses-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115663,"registerId":"commonwealth-F2006B09110-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-6/23 - Inverter Fuses - 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)  DHC-6 (Twin Otter) Series Aeroplanes\n\n \n\nAD/DHC-6/23 Inverter Fuses - Replacement 11/70\n\nApplicability: All models S/Nos. 6 - 427 except S/N 426 & fitted with PC15 & PC15A inverters. Document:              De Havilland of Canada SB No. 6/263.\n\nCompliance: Before 30 January 1976.\n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's operative scope is consistent with its title and applicability statement: it mandates replacement of inverter fuses for DHC-6 aeroplanes in the stated serial-number range fitted with PC15 or PC15A inverters and refers to Service Bulletin No. 6/263 for the required work. The instrument itself does not expand or narrow that scope beyond those explicit terms."},"complexity_factors":["Narrow and specific applicability (single aircraft type, defined serial-number range, specified inverter models)","Reliance on an external service bulletin (De Havilland SB No. 6/263) for technical details and parts","Fixed and historical compliance deadline (single date) requiring scheduling decisions","Minor ambiguity in phrasing of applicability (the clause 'except S/N 426 & fitted with PC15 & PC15A inverters' can require careful reading)","Lack of procedural detail in the directive itself, which shifts interpretive work to operators and maintenance providers"],"plain_english_summary":"This directive mandates replacement of inverter fuses on De Havilland DHC‑6 (Twin Otter) aeroplanes fitted with PC15 or PC15A inverters and with serial numbers 6–427 (except 426), in accordance with De Havilland Service Bulletin No. 6/263, to be done before 30 January 1976. It affects owners/operators of those aircraft, creating a short‑term maintenance and cost obligation and directing work to maintenance organisations and parts suppliers."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, original Airworthiness Directive from 1970 (indicated by the '11/70' suffix). It has not expanded beyond its original narrow purpose of addressing a specific inverter fuse issue on specific Twin Otter aircraft. The scope remains tightly constrained to the original safety issue."},"complexity_factors":["Single, specific technical requirement (fuse replacement)","Narrow applicability criteria (specific serial number range, specific inverter models, one excluded serial number)","No defined terms section","No cross-references to other legislation beyond the parent Civil Aviation Regulations 1998","Single compliance deadline with no conditional extensions or exceptions","References only one external technical document (Service Bulletin 6/263)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** issued by Australia's Civil Aviation Safety Authority (CASA) that mandates a safety fix for specific De Havilland DHC-6 Twin Otter aircraft.\n\n**What it does:**\n- Requires owners/operators to **replace certain inverter fuses** on affected aircraft\n- An \"inverter\" converts DC power to AC power for aircraft electrical systems; faulty fuses could cause electrical failures\n\n**Who it affects:**\n- All DHC-6 Twin Otter aircraft with **serial numbers 6 through 427**, **except serial number 426**\n- Only applies to aircraft fitted with **PC15 and PC15A model inverters**\n\n**What must be done:**\n- Follow the technical instructions in **De Havilland Service Bulletin No. 6/263**\n- Complete the replacement **before 30 January 1976**\n\n**Why it matters:**\nAirworthiness Directives are legally binding safety orders. Non-compliance means the aircraft cannot legally fly. This particular AD addresses a specific electrical system defect that could affect flight safety."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-6-23-inverter-fuses-replacement","history":"/api/acts/ad-dhc-6-23-inverter-fuses-replacement/history","analysis":"/api/acts/ad-dhc-6-23-inverter-fuses-replacement/analysis","conflicts":"/api/acts/ad-dhc-6-23-inverter-fuses-replacement/conflicts","importantCases":"/api/acts/ad-dhc-6-23-inverter-fuses-replacement/important-cases","documents":"/api/acts/ad-dhc-6-23-inverter-fuses-replacement/documents"}}