{"id":"F2006B05787","name":"AD/PA-31/81 - Heater Fuel Drain Hose - Modification","slug":"ad-pa-31-81-heater-fuel-drain-hose-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":135678,"registerId":"commonwealth-F2006B05787-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-31/81 - Heater Fuel Drain Hose - 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)  Piper PA-31 Series Aeroplanes\n\n \n\nAD/PA-31/81 Heater Fuel Drain Hose - Modification 7/79\n\nApplicability: Models PA-31, PA-31-300 and PA-31-325 with S/Nos. 31-2 to 31-7912036. PA-31- 350 with S/Nos. 31-5001 to 31-7952061.\n\n \n\nDocument: Piper SB No. 641.\n\n \n\nCompliance: Within 100 hours time in service after 31 July 1979.\n\n \n\nBackground: Deterioration of the cabin heater fuel regulator drain hose through contact with the heater air distribution box will allow any leaking fuel to drip onto the heater exhaust and create a fire hazard.\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\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1881},"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"This directive maintains its original narrow scope addressing the specific fire hazard in Piper PA-31 heater systems. It has not expanded beyond the original safety issue identified in 1979."},"complexity_factors":["Single, unambiguous operative requirement","No exceptions, nested conditions, or cross-references to other legislative provisions","Applicability limited to specific aircraft models and serial number ranges only","Simple temporal compliance requirement (fixed date plus flight hours)"],"plain_english_summary":"**What this does:**\nThis is a safety order (called an **Airworthiness Directive**) that mandates a specific modification to prevent fires in certain Piper aircraft.\n\n**Who it affects:**\nOwners and operators of these specific Piper aeroplane models:\n*   **PA-31, PA-31-300, and PA-31-325** with serial numbers from 31-2 to 31-7912036\n*   **PA-31-350** with serial numbers from 31-5001 to 31-7952061\n\n**What is required:**\nYou must modify the cabin heater fuel regulator drain hose following the instructions in **Piper Service Bulletin No. 641**. This typically involves rerouting or replacing the hose to prevent it from rubbing against the heater air distribution box.\n\n**Why it matters:**\nThe original hose placement can cause the rubber to deteriorate. If fuel leaks from this worn hose, it can drip directly onto the hot heater exhaust system, creating a serious **fire hazard**.\n\n**Compliance deadline:**\nThe modification must be completed within **100 hours of flight time** after 31 July 1979."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-31-81-heater-fuel-drain-hose-modification","history":"/api/acts/ad-pa-31-81-heater-fuel-drain-hose-modification/history","analysis":"/api/acts/ad-pa-31-81-heater-fuel-drain-hose-modification/analysis","conflicts":"/api/acts/ad-pa-31-81-heater-fuel-drain-hose-modification/conflicts","importantCases":"/api/acts/ad-pa-31-81-heater-fuel-drain-hose-modification/important-cases","documents":"/api/acts/ad-pa-31-81-heater-fuel-drain-hose-modification/documents"}}