{"id":"F2006B04222","name":"AD/BEECH 90/30 - Heater - Differential Pressure Switches and Fuse Replacement and Inspection","slug":"ad-beech-90-30-heater-differential-pressure-switches-and-fuse-replacement-and-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":43978,"registerId":"commonwealth-F2006B04222-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BEECH 90/30 - Heater - Differential Pressure Switches and Fuse Replacement and Inspection","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)  Beechcraft 90 and 65-90 (King Air) Series Aeroplanes\n\n \n\n# AD/BEECH 90/30 Heater - Differential Pressure Switches\n\nand Fuse Replacement and Inspection\n\nApplicability: Models 65-90, 65-A90 and B90 S/Nos. LJ-1 to LJ-501.\n\n# 10/72\n\n \n\nRequirement: 1. Determine that the ventilation blower is operating. Operation of the heater is prohibited if the ventilation blower is not functioning. This determination may be made by checking for airflow out of the air distribution openings in the cockpit and/or by the sound of the blower.\n\n \n\nNote: The above inspection may be performed and certified for by the pilot in command.\n\n \n\n2.    Replace existing ventilation blower and combustion blower differential switches in accordance with Beechcraft SI No. 0500-412.\n\n \n\n3.    Inspect the heater fuse to determine that a standard fuse of proper value is installed in accordance with Beechcraft SI No. 0500-412.\n\n \n\nCompliance: For Para. 1 - Prior to each flight until incorporation of Paras. 2 and 3.\n\n \n\nFor Paras. 2 and 3 - Within 100 hours’ time in service after 3 October 1972.\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":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive is narrowly targeted to identified models/serial numbers and prescribes specific preflight and maintenance actions. The text gives no indication that its applicability or substantive reach was altered from its original stated scope."},"complexity_factors":["Narrow, fleet-limited applicability (specific models and serial numbers)","Two-tier compliance: immediate recurring preflight check until parts/inspections are incorporated, then one-off replacements/inspections","Requires following an external document (Beechcraft SI No. 0500-412) for technical steps","Compliance timing tied to a calendar reference (100 hours after 3 October 1972) which affects scheduling","Allows pilot certification of the preflight check, shifting some compliance responsibility from maintenance personnel to flight crew"],"plain_english_summary":"This airworthiness directive applies to Beechcraft 65-90, 65-A90 and B90 aeroplanes (S/N LJ-1 to LJ-501). It requires pilots to confirm the cockpit ventilation blower is working before each flight until corrective work is done, and requires replacement of ventilation and combustion blower differential pressure switches plus inspection/confirmation of the correct heater fuse per Beechcraft Service Instruction No. 0500-412 within 100 hours of 3 October 1972. Operators or owners must arrange the replacements and inspections; pilots may perform and certify the preflight check."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive focused specifically on heater system modifications for a narrow aircraft type. It has not expanded beyond its original technical safety purpose."},"complexity_factors":["Very short document (under 300 words)","Only 3 substantive requirements with clear sequential logic","Single defined applicability clause (specific aircraft models and serial numbers)","No cross-references to other legislation or regulations beyond the parent Civil Aviation Regulations 1998 citation","Simple compliance structure with two clear deadlines (per-flight vs. 100-hour timeframe)","No nested exceptions or conditional logic — requirements are absolute and straightforward"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of Beechcraft King Air 65-90, 65-A90 and B90 (SN LJ-1 to LJ-501) to address a heater safety hazard. Until permanently fixed, pilots must check ventilation blower operation before flight; within 100 flight hours after 3 October 1972, maintenance must replace two heater pressure switches and verify the heater fuse per Beechcraft Service Instruction No. 0500-412. It prevents heater-related fire or carbon monoxide risks to crews and passengers."}},"importantCases":[],"_links":{"self":"/api/acts/ad-beech-90-30-heater-differential-pressure-switches-and-fuse-replacement-and-inspection","history":"/api/acts/ad-beech-90-30-heater-differential-pressure-switches-and-fuse-replacement-and-inspection/history","analysis":"/api/acts/ad-beech-90-30-heater-differential-pressure-switches-and-fuse-replacement-and-inspection/analysis","conflicts":"/api/acts/ad-beech-90-30-heater-differential-pressure-switches-and-fuse-replacement-and-inspection/conflicts","importantCases":"/api/acts/ad-beech-90-30-heater-differential-pressure-switches-and-fuse-replacement-and-inspection/important-cases","documents":"/api/acts/ad-beech-90-30-heater-differential-pressure-switches-and-fuse-replacement-and-inspection/documents"}}