{"id":"F2006B04710","name":"AD/BELL 47/88 - Auxiliary Fuel System - Modification","slug":"ad-bell-47-88-auxiliary-fuel-system-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44474,"registerId":"commonwealth-F2006B04710-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BELL 47/88 - Auxiliary Fuel System - Modification","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBell Helicopter Textron 47 (All Variants) Series Helicopters\n\nAD/BELL 47/88 Auxiliary Fuel System \\- Modification 5/83\n\nApplicability: All Model 47G Series helicopters equipped with Soloy turbine conversion utilizing Chadwick C-27 auxiliary fuel systems installed per supplemental type certificate SH 139WE.\n\nRequirement: Part 1: Install a placard readily visible to the pilot in the cabin with the following annotation.\n\nWARNING\n\n“USABLE AUX. FUEL LIMITED TO HALF AVAILABLE QTY. AT T/O”\n\nPart 2: Install Chadwick C-27 FM flow monitor kit as applicable to Bell 47 Series.\n\nNote: Soloy Conversion SL-20-660 and Rev. 1. FAA AD 82-16-12. Chadwick SB 20- 81-01 Refer.\n\nCompliance: Part 1: Within 10 hours time in service after 10th April, 1983.\n\nPart 2: Within 300 hours time in service or 6 months after 31st May, 1983 whichever occurs first.\n\nBackground: Tests conducted by the auxiliary fuel system manufacturer have shown that the loss of one auxiliary tank fuel pump will result in only half the usable auxiliary fuel being available in flight. When such a failure occurs no warning is provided.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in a specific aircraft modification. It has not expanded beyond its original purpose of mitigating fuel pump failure risks in Bell 47 helicopters with Chadwick auxiliary fuel systems."},"complexity_factors":["Very short document (approximately 200 words)","Only 2 defined/model references (Bell 47G Series, Chadwick C-27)","Simple two-part structure with clear sequential requirements","Single cross-reference to FAA AD and manufacturer service bulletins in background only","No nested exceptions or conditional logic — straightforward applicability and compliance dates","Technical but not legally complex; written for aircraft mechanics and pilots rather than lawyers"],"plain_english_summary":"This CASA Airworthiness Directive mandates that Bell 47G helicopters modified with the Chadwick C‑27/Soloy auxiliary fuel system display a cockpit warning placard limiting usable aux fuel to half and install a Chadwick C‑27 fuel flow monitor. It responds to an undetected pump-failure loss of half the auxiliary fuel that could cause fuel starvation, and applies to affected owners/operators with specified compliance timeframes."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive retains a narrow, targeted scope confined to Bell 47G helicopters with the specified Soloy/Chadwick auxiliary fuel installation and prescribes two corrective measures (a cockpit placard and installation of a flow monitor). It does not expand applicability beyond that originally identified in the directive and related referenced documents."},"complexity_factors":["Narrow, equipment‑specific applicability (only Model 47G with Soloy conversion using Chadwick C‑27 auxiliary fuel systems).","Two distinct compliance actions with different timeframes (placard: 10 hours TIS; flow monitor: 300 hours TIS or 6 months).","Technical installation requirement for the Chadwick C‑27 FM flow monitor kit (may require parts, qualified maintenance personnel and STC familiarity).","Operational implication from placard text that limits usable auxiliary fuel in pilot calculations (affects flight planning and fuel management).","Reference to other documents (Soloy conversion SL‑20‑660, FAA AD 82‑16‑12, Chadwick SB 20‑81‑01) creates dependency on external service/airworthiness material.","\"As applicable\" language introduces limited operator/operator-designer discretion about kit applicability and installation scope.","Compliance tracking and recordkeeping burden on owners/operators to meet short mandated windows."],"plain_english_summary":"This airworthiness directive requires owners/operators of Bell 47G helicopters fitted with a Soloy turbine conversion and Chadwick C‑27 auxiliary fuel system to fit a cockpit placard warning that only half the auxiliary fuel is usable if one auxiliary tank pump fails, and to install a Chadwick C‑27 flow‑monitor kit where applicable. The regulator sets short deadlines (placard within 10 flight hours; flow monitor within 300 hours or six months). Operators pay for the work and must change fuel‑planning and maintenance to manage undetected pump failures."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bell-47-88-auxiliary-fuel-system-modification","history":"/api/acts/ad-bell-47-88-auxiliary-fuel-system-modification/history","analysis":"/api/acts/ad-bell-47-88-auxiliary-fuel-system-modification/analysis","conflicts":"/api/acts/ad-bell-47-88-auxiliary-fuel-system-modification/conflicts","importantCases":"/api/acts/ad-bell-47-88-auxiliary-fuel-system-modification/important-cases","documents":"/api/acts/ad-bell-47-88-auxiliary-fuel-system-modification/documents"}}