{"id":"F2006B08832","name":"AD/DC4/26 - Feathering Pump Line - Replacement","slug":"ad-dc4-26-feathering-pump-line-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52278,"registerId":"commonwealth-F2006B08832-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DC4/26 - Feathering Pump Line - Replacement","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)  Douglas DC4 Series Aeroplanes\n\n \n\nAD/DC4/26 Feathering Pump Line - Replacement NK\n\nApplicability: All models.\n\n \n\nRequirement: Remove the duralumin pump assembly (P/N 5229000) running from the propeller feathering pump to the firewall and replace with 5/8 in. outside diameter x 18 SWG stainless steel or cadmium plated chrome molybdenum tubing; or\n\n \n\nANOs Part 100, Appendix “A” Notice No. 22/6; or ANO 105.1.16.2.5.25.\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":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a narrow, technical airworthiness directive (AD) that has not expanded beyond its original purpose. It addresses a specific mechanical defect in a specific aircraft type and remains confined to that safety-critical maintenance action."},"complexity_factors":["Single, specific mechanical requirement with no conditional logic","Only one defined term (P/N 5229000 — part number)","No cross-references to other legislation sections beyond optional alternative compliance paths","Straightforward applicability ('All models') with no exceptions or exemptions","Physical dimensions specified in imperial units (5/8 in., 18 SWG) requiring no legal interpretation","Document is essentially a maintenance bulletin converted to regulatory form"],"plain_english_summary":"This is a **safety directive for old Douglas DC-4 aircraft** (four-engine propeller planes from the 1940s). It orders owners and operators to **replace a specific fuel or hydraulic line** that runs from the propeller feathering pump to the firewall.\n\n**What it does:**\n- **Targets:** The \"feathering pump line\" — a pipe that supplies fluid to the mechanism that lets pilots adjust propeller blades to a safe position when an engine fails.\n- **The problem:** The original part was made of **duralumin** (an early aluminium alloy) which can corrode or fail over time.\n- **The fix:** Replace it with stronger **stainless steel or cadmium-plated chrome-moly tubing** (5/8 inch diameter, 18 gauge wall thickness).\n\n**Who it affects:**\n- Anyone operating Douglas DC-4 series aircraft in Australia — mostly **heritage aviation operators, museums, and vintage cargo flyers**.\n\n**Why it matters:**\n- If this line fails, pilots can't \"feather\" the propeller on a dead engine. An unfeathered propeller windmills in the airflow, creating massive drag that can make the aircraft uncontrollable or cause it to crash. This is a **critical flight safety issue** for these elderly aircraft.\n\n**Compliance alternatives:**\n- Operators can also comply by following two older British aviation notices (ANOs) listed as alternatives."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument, as presented, directs a specific physical replacement for the propeller feathering pump line on all DC-4 series aeroplanes and provides alternative compliance references. There is no text in this instrument indicating an expansion or narrowing of that scope beyond replacing the listed duralumin assembly with the specified tubing or following the cited ANO alternatives (AD/DC4/26, Applicability; AD/DC4/26, Requirement)."},"complexity_factors":["Single, clearly stated mechanical action (remove P/N 5229000 and replace with specified tubing). (Requirement)","Applicability covers all models of the type, widening operational reach but not adding technical variation. (Applicability)","Precise physical specification required (5/8 in. O.D. x 18 SWG; stainless steel or cadmium-plated chrome-molybdenum), constraining procurement. (Requirement)","Alternative compliance options referenced (ANOs Part 100 Appendix A Notice No. 22/6; ANO 105.1.16.2.5.25) add a procedural choice for operators. (Requirement)","No compliance timeframe or scheduling detail in the text, creating uncertainty for planning and budgeting. (Requirement)","Operational implementation requires coordination between operator and maintenance organisation and incurs parts, labour and downtime costs (implied by the replacement requirement). (Requirement)"],"plain_english_summary":"The AD mandates removal of a duralumin pump assembly (part 5229000) on the propeller feathering pump line and its replacement with 5/8\" OD x 18 SWG tubing of stainless steel or cadmium‑plated chrome‑moly for all Douglas DC‑4 series aeroplanes.  \n\nAircraft owners/operators and their maintenance organisations must carry out and fund the work (or follow the cited ANO alternative compliance routes), shifting procurement and maintenance scheduling onto operators."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dc4-26-feathering-pump-line-replacement","history":"/api/acts/ad-dc4-26-feathering-pump-line-replacement/history","analysis":"/api/acts/ad-dc4-26-feathering-pump-line-replacement/analysis","conflicts":"/api/acts/ad-dc4-26-feathering-pump-line-replacement/conflicts","importantCases":"/api/acts/ad-dc4-26-feathering-pump-line-replacement/important-cases","documents":"/api/acts/ad-dc4-26-feathering-pump-line-replacement/documents"}}