{"id":"F2006B10719","name":"AD/HU 369/56 - Auxiliary Fuel System - Modification","slug":"ad-hu-369-56-auxiliary-fuel-system-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116700,"registerId":"commonwealth-F2006B10719-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HU 369/56 - 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)  \nMcDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters\n\nAD/HU 369/56 Auxiliary Fuel System \\- Modification 3/83\n\nApplicability: All models with Chadwick C-20 auxiliary fuel system installed per supplemental type certificate SH129WE.\n\nRequirement: Part 1: Install placard readily visible to the pilot in the cabin with the following annotation:-\n\nWARNING “USABLE AUX. FUEL LIMITED TO HALF AVAILABLE QTY. AT T/O”\n\nPart 2: Install Chadwick C-20-FM flow monitor kit.\n\nNote: FAA AD 82-14-01 and Chadwick SB20-81-01 refer.\n\nCompliance: Part 1: Within 10 hours time in service after 22 February 1983.\n\nPart 2: Within 300 hours time in service, or 6 months after 31 March 1983.\n\nThe placard installed as per Part 1 above, may be removed, provided the revised flight manual supplement, Chadwick Auxiliary Fuel System C-20 dated 21 October 1981, is incorporated into the rotorcraft flight manual.\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":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This directive expands regulatory obligations for affected rotorcraft by adding equipment and placarding requirements that did not previously exist for these installations. It mandates (1) a visible cockpit placard warning about reduced usable auxiliary fuel if one pump fails, (2) installation of a flow monitor kit, and (3) an option to remove the placard only after incorporation of a specified revised flight manual supplement. Deadlines for each action are specified, creating new short‑term compliance duties for owners/operators (Requirement; Compliance; Note)."},"complexity_factors":["Narrow applicability: applies only to helicopters with Chadwick C-20 installed under supplemental type certificate SH129WE (Applicability).","Two distinct compliance actions with different deadlines: immediate placard within 10 hours TIS after 22 Feb 1983 and flow‑monitor installation within 300 hours TIS or 6 months after 31 Mar 1983 (Compliance: Part 1 & Part 2).","Conditional relief: placard may be removed if a specific revised flight manual supplement (Chadwick C-20 dated 21 Oct 1981) is incorporated, creating an alternative compliance path (Requirement/Note).","Cross‑references to external materials for technical details and background (FAA AD 82-14-01 and Chadwick SB20-81-01), requiring operators to consult other documents.","Clear safety rationale tied to manufacturer test results (Background) but no technical detail in the directive about diagnostic thresholds, leaving implementation details to kit/service instructions.","Compliance burden falls on owners/operators (installation and possible flight manual amendment) and involves scheduling within operational hours; enforcement requires maintenance records or flight manual evidence."],"plain_english_summary":"This airworthiness directive requires operators of helicopters fitted with the Chadwick C-20 auxiliary fuel system (installed under STC SH129WE) to fit a cockpit placard warning that only half the auxiliary fuel is usable if one pump fails and to install a Chadwick flow‑monitor kit. It matters because manufacturer tests show losing one auxiliary pump leaves only half the usable aux fuel with no onboard warning. Owners/operators pay for and must schedule the installations within short, specified timeframes to manage that risk."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific technical defect in a specific aircraft system. It has not expanded beyond its original purpose of mandating a warning placard and flow monitor installation for the Chadwick C-20 auxiliary fuel system."},"complexity_factors":["Very short document (under 300 words)","Only 2 defined compliance actions (Part 1 and Part 2)","Single applicability criterion (specific auxiliary fuel system model)","One conditional exception (placard removal permitted upon flight manual update)","No nested definitions or cross-references to other legislation sections","Clear deadlines with specific dates and flight hour thresholds","References only to external technical documents (FAA AD and manufacturer service bulletin) for context, not for operative requirements"],"plain_english_summary":"This AD requires operators of certain McDonnell Douglas (Hughes) and Kawasaki 369 helicopters fitted with the Chadwick C‑20 auxiliary fuel system (STC SH129WE) to address a safety defect where a single pump failure leaves half the auxiliary fuel unusable without pilot warning. \n\nIt mandates an immediate cockpit warning placard and the later installation of a flow‑monitor kit (with an FM replacement option via a revised flight manual), preventing unexpected fuel exhaustion."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hu-369-56-auxiliary-fuel-system-modification","history":"/api/acts/ad-hu-369-56-auxiliary-fuel-system-modification/history","analysis":"/api/acts/ad-hu-369-56-auxiliary-fuel-system-modification/analysis","conflicts":"/api/acts/ad-hu-369-56-auxiliary-fuel-system-modification/conflicts","importantCases":"/api/acts/ad-hu-369-56-auxiliary-fuel-system-modification/important-cases","documents":"/api/acts/ad-hu-369-56-auxiliary-fuel-system-modification/documents"}}