{"id":"F2009L02968","name":"AD/CFM56/32 - Engine Hydromechanical Unit","slug":"ad-cfm56-32-engine-hydromechanical-unit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":80470,"registerId":"commonwealth-F2009L02968-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"CFM International Turbine Engines - CFM5","sectionType":"division","heading":"CFM International Turbine Engines - CFM56 Series","content":"### CFM International Turbine Engines - CFM56 Series\n\n| AD/CFM56/32 | Engine Hydromechanical Unit | 10/2009 TX |\n| ----------- | --------------------------- | ---------- |\n\n| Applicability: | CFM International SA CFM56-5B engine models equipped with Hydromechanical units (HMU) VIN 8061-532 (P/N 1348M79P10), VIN 8061-535 (P/N 1348M79P13), VIN 8061-536 (P/N 1348M79P14), Serial Numbers (S/N) as identified within paragraph 1.A of CFM Service Bulletin CFM56-5B S/B 73-0238 Revision 1 and which have not been modified in accordance with CFM56-5A S/B 73-0208,CFM56-5B S/B 73-0239 or CFM56-5C S/B 73-0180.Note 1: These engines are known to be installed on, but not limited to Airbus A318, A319, A320 and A321 series aeroplanes.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Requirement:   | 1. Check engine records for any occurrence of ECAM (Electronic Centralized Aircraft Monitoring) “ENG X START FAULT- ENG X STALL” and/or “ENG X COMPRESSOR VANE” warnings since entry into service of the HMUs.Note 2: The letter “X” in ECAM warnings above is a placeholder for a numeral varying from 1 to 2.2. For engines which have displayed before the effective date of this AD, any of the ECAM warnings described in Requirement 1 of this AD, replace the affected HMU with a serviceable unit.3. For engines which have never displayed any of the ECAM warnings described in Requirement 1 of this AD:a. From the effective date of this AD, after any ECAM warnings described in Requirement 1 of this AD (during air or ground operations): Replace the affected HMU with a serviceable unit.b. If both engines on the same aeroplane are found with HMUs S/N as identified within paragraph 1.A of SB CFM56-5B S/B 73-0238 Revision 1, replace at least one HMU with a serviceable unit.Replacement of an HMU with a serviceable unit must be done in accordance with paragraph 3.C of CFM Service Bulletin CFM56-5B S/B 73-0238 Revision 1. |\n\n|             | Optional Terminating Action: Modification of both HMUs per one of the following SBs: CFM56-5A S/B 73-0208, CFM56-5B S/B 73-0239 or CFM56-5C S/B 73-0180 is an alternative corrective action for the requirements of this AD.The use of later approved revisions of these documents is acceptable for compliance with the requirements of this AD.Note 3: EASA AD 2009-0154-E dated 17 July 2009 refers.                                     |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | For Requirement 1 - Within 24 hours after the effective date of this AD, unless previously accomplished.For Requirement 2 - Before further flight, unless previously accomplished.For Requirement 3.a. - Before further flight.For Requirement 3.b. - Within 30 days after the effective date of this AD.                                                                                                                                   |\n|             | This Airworthiness Directive becomes effective on 27 July 2009.                                                                                                                                                                                                                                                                                                                                                                             |\n| Background: | In-flight compressor stall events have occurred on CFM56-5B turbofan engines. These events could have been caused by malfunction of the HMU Variable Stator Vanes (VSV)/Variable Bleed Valves (VBV) Scored Vanes and could lead to in-flight shutdown of the engine, which can result in a catastrophic effect at aircraft level if more than one engine is affected. This AD mandates the inspection and replacement of the affected HMUs. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n23 July 2009","sortOrder":0},{"sectionNumber":"AD/CFM56/32","sectionType":"part","heading":"AD/CFM56/32","content":"## AD/CFM56/32","sortOrder":1},{"sectionNumber":"Engine Hydromechanical Unit","sectionType":"part","heading":"Engine Hydromechanical Unit","content":"## Engine Hydromechanical Unit","sortOrder":2},{"sectionNumber":"10/2009 TX","sectionType":"part","heading":"10/2009 TX","content":"## 10/2009 TX","sortOrder":3}],"analysis":{"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"},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The directive's scope aligns with its stated safety objective: it targets specific HMU VINs/S/Ns on CFM56-5B engines and mandates inspection, replacement or specified modification to mitigate compressor-stall risk. No change to the covered population or core intent is indicated in the text supplied."},"complexity_factors":["Technical specificity: applicability limited to CFM56-5B engines with particular HMU VINs/P/Ns and S/Ns (Applicability).","Conditional requirements: actions depend on historical ECAM fault occurrences versus first-time events (Requirement 1–3).","Multiple compliance timeframes: immediate record check (24 hours), before next flight, and 30-day replacement window (Compliance).","Cross-references to external documents: mandatory work and terminating actions require following specific CFM Service Bulletins and acceptable later revisions (Requirement text; Optional Terminating Action).","Operational trigger points: replacement may be required after ECAM warnings during air or ground ops, implicating line maintenance procedures (Requirement 3.a).","Safety consequence linkage: ties to in-flight compressor stalls and potential engine shutdowns, raising urgency and potential operational disruption (Background).","Fleet-level interaction: if both engines on one aeroplane have affected HMUs, at least one must be replaced, creating coordination and parts-supply considerations (Requirement 3.b).","Narrowly defined remedial action: replacement must follow a specified paragraph of the service bulletin, limiting maintenance options and increasing dependence on OEM procedures (Requirement 3.C reference)."],"plain_english_summary":"This Airworthiness Directive requires operators of CFM56-5B engines fitted with certain Hydromechanical Units (HMUs) to check maintenance records for specific ECAM warnings and to replace any affected HMU or fit a serviceable unit within prescribed time limits. As an alternative, operators may modify both HMUs using specified CFM service bulletins as a terminating action.\n\nIt affects airlines and maintenance organisations operating Airbus A318–A321 series aircraft (and others) with the listed HMU VINs/S/Ns. It matters because the HMU fault is linked to in‑flight compressor stalls and potential engine shutdowns, so compliance imposes inspection, parts replacement or modification and adherence to service bulletin procedures."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a standard, targeted Airworthiness Directive addressing a specific safety-critical defect in a defined population of aircraft engines. The scope remains tightly focused on the identified HMU malfunction issue and does not extend beyond necessary safety remediation."},"complexity_factors":["Multiple conditional requirements based on whether warnings have occurred (Requirements 1, 2, and 3 create branching compliance paths)","Cross-references to three external manufacturer service bulletins (CFM56-5B S/B 73-0238, plus three terminating action SBs) without reproducing their content","Specific part number and serial number identification requiring lookup in external documents","Nested applicability criteria: engine model + specific HMU part numbers + specific serial numbers + modification status exclusions","Dual-engine scenario creates additional compliance obligation (Requirement 3.b) beyond single-engine cases","Multiple compliance timeframes: 24 hours, before further flight, and 30 days depending on circumstance"],"plain_english_summary":"This AD mandates that operators of Airbus A318/A319/A320/A321 with CFM56-5B engines inspect and, where indicated, replace or modify specific Hydromechanical Units (HMUs) due to a fault that can cause compressor stalls and possible engine shutdown.  \n\nIt affects aircraft with the listed HMU part/serial numbers and matters because unaddressed HMU failures can lead to one or both engines shutting down in flight, creating a high safety risk."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cfm56-32-engine-hydromechanical-unit","history":"/api/acts/ad-cfm56-32-engine-hydromechanical-unit/history","analysis":"/api/acts/ad-cfm56-32-engine-hydromechanical-unit/analysis","conflicts":"/api/acts/ad-cfm56-32-engine-hydromechanical-unit/conflicts","importantCases":"/api/acts/ad-cfm56-32-engine-hydromechanical-unit/important-cases","documents":"/api/acts/ad-cfm56-32-engine-hydromechanical-unit/documents"}}