{"id":"F2006B03194","name":"AD/B747/301 - Discrepant Hydraulic Valves","slug":"ad-b747-301-discrepant-hydraulic-valves","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42566,"registerId":"commonwealth-F2006B03194-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.001.png)  \n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)  \n\nBoeing 747 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/B747/301 Discrepant Hydraulic Valves ","sectionType":"part","heading":"AD/B747/301 Discrepant Hydraulic Valves 4/2004","content":"# AD/B747/301 Discrepant Hydraulic Valves 4/2004\n\nApplicability: Model 747 series aeroplanes, as listed in Boeing Alert Service Bulletin (ASB) 747- 29A2102, dated June 29, 2000.\n\nRequirement: 1. Check maintenance records or perform a general visual inspection of each engine strut to determine whether any discrepant valve is installed as a hydraulic supply (fire) shutoff valve for the engine-driven pump. A discrepant valve is a Circle Seal valve part number (P/N) S270T010-3 or a valve that cannot be readily identified. Identify the part in accordance with Boeing ASB 747- 29A2102. If no discrepant valve is installed, no further action is required.\n\n    2. For any discrepant valve found during the part identification required by Requirement 1 of this Directive: Carry out a hydraulic supply (fire) shutoff valve test, in accordance with paragraph 3.J. of the Accomplishment Instructions of Boeing ASB 747-29A2102.\n\n    3. If the valve passes the test, as detailed in Requirement 2 of this Directive, repeat the test in accordance with paragraph 3.J. of the Accomplishment Instructions of Boeing ASB 747-29A2102.\n\n    4. If the valve does not pass the test, as detailed in Requirement 2 of this Directive, replace the valve with a serviceable valve, P/N S270T010-3, 10-3200- 1, 10- 3200-2, or a valve identified in paragraph 3.I. of the Accomplishment Instructions of Boeing ASB 747-29A2102; and do a hydraulic supply (fire) shutoff valve test; in accordance with paragraph 3.J. of the Accomplishment Instructions of Boeing ASB 747-29A2102.\n\nReplacement with a serviceable valve, P/N 10-3200-1, 10-3200-2, or a valve identified in paragraph 3.I. of the Accomplishment Instructions of Boeing ASB 747-29A2102, terminates the repetitive tests required by Requirement 3 of this Directive.\n\nIf a P/N S270T010-3 valve is installed as a replacement, repeated testing must be performed in accordance with Requirement 3 of this Directive.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD remains narrowly focused on identifying, testing and replacing discrepant hydraulic (fire) shutoff valves on Boeing 747 series aeroplanes listed in the referenced ASB. It does not expand the subject matter beyond that original safety purpose. The measure delegates procedural detail to Boeing ASB 747-29A2102 and sets conditional requirements (testing vs replacement) but does not materially broaden the population affected or add unrelated regulatory duties."},"complexity_factors":["Relies on an external manufacturer document (Boeing ASB 747-29A2102) for detailed procedures and timing (paragraphs 3.I and 3.J referenced)","Conditional workflow with nested outcomes (identify → test → pass/fail → repeat or replace)","Specific part-number logic that changes compliance obligations (P/N S270T010-3 vs P/N 10-3200-1/10-3200-2 vs ASB-approved valves)","Repetitive testing obligation that is terminated only by specific replacements (creates ongoing compliance stream)","Ambiguity in this excerpt about explicit test intervals and exact compliance deadlines (delegated to ASB), increasing interpretive work for operators"],"plain_english_summary":"**What this directive does (mechanically)**\n\n- Applies to Boeing 747 series aeroplanes listed in Boeing Alert Service Bulletin (ASB) 747-29A2102 (see \"Applicability\").\n- Requires operators or maintenance organisations to check whether a \"discrepant\" hydraulic supply (fire) shutoff valve is installed on each engine strut. A \"discrepant\" valve is either a Circle Seal valve part number (P/N) S270T010-3 or a valve that cannot be readily identified (Requirement 1).\n- If a discrepant valve is present, the valve must be tested as a hydraulic supply (fire) shutoff valve according to the test procedure specified in paragraph 3.J. of Boeing ASB 747-29A2102 (Requirement 2).\n- If the valve passes that test, the test must be repeated in accordance with paragraph 3.J. of the ASB (Requirement 3).\n- If the valve fails the test, it must be replaced with a \"serviceable\" valve (P/N 10-3200-1, 10-3200-2, P/N S270T010-3 only as a replacement if specifically allowed, or another valve identified in paragraph 3.I. of the ASB), and the replacement must be tested per paragraph 3.J. of the ASB (Requirement 4).\n- Replacing a discrepant valve with a serviceable valve of P/N 10-3200-1 or 10-3200-2 (or a valve identified in ASB paragraph 3.I.) stops the requirement for repeated testing. Replacing with P/N S270T010-3 does not stop the repeated testing requirement.\n\n**Who this affects**\n\n- Aircraft operators and owners of Boeing 747 series airplanes listed in the ASB.\n- Maintenance organisations and licensed engineers who perform inspections, tests and valve replacements.\n- Parts suppliers who stock the specified valve part numbers.\n\n**Why it matters (official rationale and how it is implemented)**\n\n- The directive is issued to correct an unsafe condition related to engine hydraulic supply (fire) shutoff valves. The AD requires identification, testing and (if necessary) replacement of valves that are either the specific Circle Seal P/N S270T010-3 or cannot be positively identified (Requirements 1–4).\n- The AD delegates the detailed test procedures and some identification guidance to Boeing ASB 747-29A2102 (paragraphs 3.I. and 3.J. are specifically referenced). That means the mechanical steps and timing for tests are governed by the ASB instructions referenced in the AD.\n\n**Practical effects, incentives and trade-offs**\n\n- Who pays: Aircraft operators pay for inspections, testing, replacements, parts and aircraft downtime.\n- Who decides: The AD prescribes the required actions; maintenance organisations decide how to schedule and execute inspections and replacements. The ASB (manufacturer) provides the procedural detail used to comply.\n- Behaviour changes required: Operators must inspect records or visually inspect engine struts to identify valve part numbers, perform repeated tests on any discrepant valve, and replace failing valves with specified serviceable parts. If operators replace discrepant valves with P/N 10-3200-1/10-3200-2 (or ASB-approved equivalents), they can stop the repetitive tests.\n- Incentives created: Because replacing with P/N 10-3200-1 or 10-3200-2 (or other ASB-approved valves) terminates repeated testing, operators have a commercial incentive to replace discrepant valves rather than continue periodic testing. Conversely, installing P/N S270T010-3 as a replacement preserves the need for repeated tests, so operators are incentivised to avoid using S270T010-3 where practicable.\n- Costs and opportunity costs: Costs include labour for record checks/inspections, technician time for tests, parts costs and aircraft out-of-service time. If parts are scarce or have long lead times, operators may elect repeated tests (with recurring costs) over immediate replacement, affecting scheduling and utilisation.\n- Implementation and compliance risk: The AD relies on a manufacturer ASB for test detail and identification guidance. That creates operational dependence on the ASB text (paragraphs 3.I and 3.J). Any ambiguity or later revision in the ASB could affect compliance actions or require further regulatory clarification.\n- Effects on private choice and competition: The directive prescribes specific part numbers for acceptable replacement valves. That can concentrate demand on suppliers of those part numbers; operators seeking alternatives must rely on valves identified in the ASB (paragraph 3.I) or other approved parts, which constrains substitution unless approved.\n\n**Concrete mechanisms to note**\n\n- Identification first: the AD requires looking up maintenance records or doing a visual inspection before any test (Requirement 1).\n- Test then repeat: any discrepant valve found must be tested (Requirement 2) and, if it passes, the test must be repeated per the ASB (Requirement 3).\n- Replacement ends repetition only for certain P/Ns: Replacement with P/N 10-3200-1, 10-3200-2, or other ASB-approved valves ends the repeated-test obligation (Requirement 4). Replacement with P/N S270T010-3 keeps the repeated-test obligation.\n\n(References in text: Requirements 1–4 of AD/B747/301 and paragraphs 3.I. and 3.J. of Boeing ASB 747-29A2102.)"},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific unsafe condition with a specific valve type on a specific aircraft series. The requirements follow the standard AD structure (applicability, requirement, compliance) without expansion into broader operational or maintenance areas."},"complexity_factors":["Short, single-purpose directive with only 4 sequential requirements","Minimal defined terms (only 'discrepant valve' and specific part numbers need clarification)","Clear conditional logic (if found → test → if pass repeat / if fail replace)","Single external reference to Boeing Alert Service Bulletin for technical details","No nested exceptions or cross-references to other legislation","Straightforward compliance pathway with clear termination condition"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of certain Boeing 747s (per Boeing Alert SB 747-29A2102) to check for a potentially incorrect or unidentifiable engine-driven hydraulic fire shutoff valve (PN S270T010-3). Where present, the valve must be tested and then either kept on a defined test interval if serviceable or replaced if it fails. The AD prevents a faulty valve from blocking hydraulic shutoff during an engine fire, reducing serious safety risk."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-301-discrepant-hydraulic-valves","history":"/api/acts/ad-b747-301-discrepant-hydraulic-valves/history","analysis":"/api/acts/ad-b747-301-discrepant-hydraulic-valves/analysis","conflicts":"/api/acts/ad-b747-301-discrepant-hydraulic-valves/conflicts","importantCases":"/api/acts/ad-b747-301-discrepant-hydraulic-valves/important-cases","documents":"/api/acts/ad-b747-301-discrepant-hydraulic-valves/documents"}}