{"id":"F2006B05511","name":"AD/PA-23/84 - Exhaust System - Inspection and Modification","slug":"ad-pa-23-84-exhaust-system-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":46366,"registerId":"commonwealth-F2006B05511-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PA-23/84 - Exhaust System - Inspection and 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-23 (Apache and Aztec) Series Aeroplanes\n\n \n\nAD/PA-23/84 Exhaust System - Inspection and Modification 11/82\n\nApplicability: PA-23-250 (6 places) Aztec S/Nos. 27-2505 to 27-8054019 (normally aspirated only).\n\n \n\nDocument: Piper SB 662.\n\n \n\nCompliance: If not already accomplished, within 100 hours time in service after 31 December 1982.\n\n \n\nBackground:  Reports have been received of exhaust system crossover tubes disconnecting at the forward slip-joint connections. This condition has led to burning of the engine nose cowling and carburettor heat muff. The fitting of a safety cable to the slip joint as outlined in Piper SB 662 should prevent further occurrences.\n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1948},"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"The directive maintains its original narrow scope targeting specific Piper Aztec aircraft serial numbers for a mandatory exhaust system safety modification."},"complexity_factors":["Single, specific mechanical requirement","Clear applicability limited to specific aircraft serial numbers","No defined terms or cross-references to other legislation","Simple compliance deadline (100 hours time in service)"],"plain_english_summary":"**What this does:**\nThis directive orders owners and operators of specific Piper Aztec aircraft to install a safety cable on the exhaust system crossover tubes to prevent them from disconnecting.\n\n**Who it affects:**\nOwners and operators of Piper PA-23-250 Aztec aircraft (normally aspirated only) with serial numbers between 27-2505 and 27-8054019.\n\n**What must be done:**\nIf not already done, install a safety cable on the exhaust crossover tube slip-joint connections following the instructions in Piper Service Bulletin 662. This must be completed within 100 hours of flight time after 31 December 1982.\n\n**Why it matters:**\nThe exhaust crossover tubes have been disconnecting at the slip-joints, causing hot exhaust gases to burn through the engine nose cowling and carburettor heat muff. This creates a fire risk and could damage critical engine systems. The safety cable prevents the joint from separating, eliminating this safety hazard."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pa-23-84-exhaust-system-inspection-and-modification","history":"/api/acts/ad-pa-23-84-exhaust-system-inspection-and-modification/history","analysis":"/api/acts/ad-pa-23-84-exhaust-system-inspection-and-modification/analysis","conflicts":"/api/acts/ad-pa-23-84-exhaust-system-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-pa-23-84-exhaust-system-inspection-and-modification/important-cases","documents":"/api/acts/ad-pa-23-84-exhaust-system-inspection-and-modification/documents"}}