{"id":"F2006B09730","name":"AD/F27/38 - ADF Sense Antenna - Modification","slug":"ad-f27-38-adf-sense-antenna-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":115920,"registerId":"commonwealth-F2006B09730-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F27/38 - ADF Sense Antenna - 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)  Fokker F27 Series Aeroplanes\n\n \n\nAD/F27/38 ADF Sense Antenna - Modification 12/67\n\nApplicability: All models fitted with Bendix type DFA-70A ADF equipment.\n\n \n\nRequirement: Modify the sense antenna to achieve the following minimum performance characteristics:-\n\n \n\n(a)     Effective Height : Not less than 0.25 metres.\n\n \n\n(b)     Sensitivity Product Value : Between the limits of 12 and 25 micro-microfarads- meters.\n\n \n\n(c)     Total capacity of antenna and transmission line presented to receiver input terminals : 270 micro-microfarads + 10%.DE\n\n \n\n(d)     Tilt Angle : between the limits of -20º and +10º.\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":1693},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This airworthiness directive maintains its original narrow technical scope regarding specific antenna modifications for defined aircraft equipment. There is no evidence of scope creep beyond the original safety intent."},"complexity_factors":["Technical engineering specifications without explanatory context for non-specialists","Use of deprecated or specialized units (micro-microfarads) without modern equivalents","No definitions provided for specialized aeronautical terms","Absence of procedural guidance on how to achieve compliance"],"plain_english_summary":"This Airworthiness Directive requires owners and operators of **Fokker F27 aircraft** fitted with **Bendix DFA-70A ADF equipment** to modify the Automatic Direction Finder (ADF) sense antenna to meet specific technical standards.\n\n**What it does:**\nMandates modifications to navigation equipment to ensure accurate directional readings and flight safety.\n\n**Technical requirements:**\nThe modified antenna must achieve:\n- **Effective height:** At least 0.25 metres\n- **Sensitivity product value:** Between 12 and 25 micro-microfarads-meters (a measurement of electrical performance)\n- **Total capacity:** 270 micro-microfarads, plus or minus 10%, measured at the receiver input terminals\n- **Tilt angle:** Between -20 and +10 degrees\n\n**Who it affects:**\nOperators and maintenance organisations responsible for Fokker F27 aircraft equipped with the specified Bendix navigation systems.\n\n**Why it matters:**\nThese specifications ensure the ADF equipment—which helps pilots determine their bearing relative to ground-based radio beacons—operates reliably and accurately, directly impacting aviation safety."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f27-38-adf-sense-antenna-modification","history":"/api/acts/ad-f27-38-adf-sense-antenna-modification/history","analysis":"/api/acts/ad-f27-38-adf-sense-antenna-modification/analysis","conflicts":"/api/acts/ad-f27-38-adf-sense-antenna-modification/conflicts","importantCases":"/api/acts/ad-f27-38-adf-sense-antenna-modification/important-cases","documents":"/api/acts/ad-f27-38-adf-sense-antenna-modification/documents"}}