{"id":"F2006B05689","name":"AD/PA-31/103 - Heater Air Distribution Box Thermal Switch","slug":"ad-pa-31-103-heater-air-distribution-box-thermal-switch","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":135465,"registerId":"commonwealth-F2006B05689-current","compilationNumber":null,"startDate":"2026-04-03","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-31/103 - Heater Air Distribution Box Thermal Switch","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-31/103 Heater Air Distribution Box Thermal Switch 6/82\n\nApplicability: All models PA-31T1 with S/Nos. 31T-7804001 to 31T-8104069. All models PA-31T with S/Nos. 31T-7400001 to 31T-8120059.\n\n \n\nRequirement: Action in accordance with Piper SB No. 731. Compliance:  Within 100 hours time in service after 30 June 1982.\n\nBackground:  Failure of a heater recirculation blower could cause an overheat situation in the heater/cabin air system.\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":1540},"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"The directive maintains a narrow, targeted scope addressing the specific safety defect of heater overheat in defined aircraft models. No expansion beyond the original safety intent is evident."},"complexity_factors":["Single, unambiguous compliance requirement referencing one external standard (Piper SB 731)","Applicability limited to specific aircraft models and serial number ranges with no ambiguity","Simple deadline calculation (100 hours time-in-service after a fixed date)","No defined terms, exceptions, or conditional provisions"],"plain_english_summary":"**What this is:** A mandatory safety instruction (called an Airworthiness Directive) for owners of specific Piper PA-31T Cheyenne aircraft.\n\n**What it requires:** Owners must modify the heater air distribution box by installing a thermal switch — essentially a safety cut-off that shuts down the heating system if it overheats. The work must be done exactly as described in Piper Service Bulletin No. 731.\n\n**Who it affects:** Owners and operators of specific Piper Cheyenne aircraft:\n- PA-31T1 models with serial numbers 31T-7804001 through 31T-8104069\n- PA-31T models with serial numbers 31T-7400001 through 31T-8120059\n\n**Why it matters:** If the heater's recirculation blower fails, the system can overheat, creating a fire risk in the cabin. The thermal switch prevents this by automatically shutting off the heater when temperatures get dangerously high.\n\n**Deadline:** The modification must be completed within 100 hours of flight time after 30 June 1982."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-31-103-heater-air-distribution-box-thermal-switch","history":"/api/acts/ad-pa-31-103-heater-air-distribution-box-thermal-switch/history","analysis":"/api/acts/ad-pa-31-103-heater-air-distribution-box-thermal-switch/analysis","conflicts":"/api/acts/ad-pa-31-103-heater-air-distribution-box-thermal-switch/conflicts","importantCases":"/api/acts/ad-pa-31-103-heater-air-distribution-box-thermal-switch/important-cases","documents":"/api/acts/ad-pa-31-103-heater-air-distribution-box-thermal-switch/documents"}}