{"id":"F2008L00253","name":"AD/ARRIUS/14 - Engine Electronic Control Units","slug":"ad-arrius-14-engine-electronic-control-units","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":72483,"registerId":"commonwealth-F2008L00253-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Turbomeca Turbine Engines - Arrius Serie","sectionType":"division","heading":"Turbomeca Turbine Engines - Arrius Series","content":"### Turbomeca Turbine Engines - Arrius Series\n\n| AD/ARRIUS/14 | Engine Electronic Control Units | 3/2008 DM |\n| ------------ | ------------------------------- | --------- |\n\n| Applicability: | Arrius 2B1, 2B1A, 2B2, 2K1 and 2K2 engines, all serial numbers.                                                                                                                                                                                                              |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|                | Note 1: These engines are known to be installed on, but not limited to, Eurocopter Deutschland EC135 and Agusta A109 twin-engine helicopters.                                                                                                                                |\n| Requirement:   | 1. Determine if the serial number of the installed engine electronic control (EEC) units is listed in the Appendix to Turbomeca Service Bulletin (SB) N°319 73 2835 Update 1 dated 21 December 2006.                                                                         |\n|                | 2. If, as a result of the Requirement 1 determination, both EEC units installed on the helicopter’s engines are found to be listed in the Appendix to SB N° 319 73 2835 Update 1 modify at least one unit in accordance with the instructions of SB N° 319 73 2835 Update 1. |\n|                | 3. Modify all remaining affected EEC units in accordance with the instructions of SB N° 319 73 2835 Update 1.                                                                                                                                                                |\n|                | 4. EEC units with a serial number as listed in the Appendix to SB N° 319 73 2835 Update 1 may not be installed on any engine as a replacement spare, unless it has been modified in accordance with the instructions of SB N° 319 73 2835 Update 1.                          |\n|                | Later revisions of SB N° 319 73 2835 Update 1 approved by the European Aviation Safety Agency (EASA) are acceptable for compliance with the requirements of this Directive.                                                                                                  |\n|                | Modifications accomplished before the effective date of this Directive in accordance with SB N° 319 73 2835 dated 9 November 2006 are acceptable for compliance with requirements of this Directive.                                                                         |\n|                | Note 2: EASA AD 2008-0018 refers.                                                                                                                                                                                                                                            |\n| Compliance:    | For Requirements 1 and 2 - Within the next 100 hours time in service (TIS) or two months, whichever occurs first after the effective date of this Directive.                                                                                                                 |\n|                | For Requirement 3 - Within 300 hours TIS or 12 months, whichever occurs first after the effective date of this Directive.                                                                                                                                                    |\n\n|             | For Requirement 4 - After 7 February 2009.                                                                                                                                                                                                                                                                                                          |\n| ----------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|             | This Airworthiness Directive becomes effective on 7 February 2008.                                                                                                                                                                                                                                                                                  |\n| Background: | The engine manufacturer has advised that a short circuit of some tantalum capacitors inside certain EEC units may lead to an in-flight shutdown on one of the two engines. Investigations have indicated that the tantalum capacitors may have become embrittled during acceptance tests performed by the supplier and are liable to short circuit. |\n|             | This Directive requires the identification and modification of EEC units that have the tantalum capacitors installed that could have become brittle during their acceptance test.                                                                                                                                                                   |\n\n![](image.001.png)  \nDavid Punshon  \nDelegate of the Civil Aviation Safety Authority\n\n29 January 2008","sortOrder":0},{"sectionNumber":"AD/ARRIUS/14","sectionType":"part","heading":"AD/ARRIUS/14","content":"## AD/ARRIUS/14","sortOrder":1},{"sectionNumber":"Engine Electronic Control Units","sectionType":"part","heading":"Engine Electronic Control Units","content":"## Engine Electronic Control Units","sortOrder":2},{"sectionNumber":"3/2008 DM","sectionType":"part","heading":"3/2008 DM","content":"## 3/2008 DM","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The Directive stays narrowly focused on identifying and modifying EEC units that may contain embrittled tantalum capacitors. It does not expand regulatory scope beyond correcting that specific hardware defect: it requires inspection, mandated modification per the OEM service bulletin, and a ban on installing unmodified listed spares after a set date. The acceptance of later EASA‑approved SB revisions and prior compliant work are procedural flexibilities rather than scope expansions."},"complexity_factors":["Short document with 4 clear operative requirements (Requirements 1–4).","Cross-reference to a single OEM Service Bulletin (SB No. 319 73 2835 Update 1) and its Appendix for serial numbers.","Acceptance of later SB revisions approved by EASA and acceptance of earlier SB compliance creates limited conditionality.","Multiple compliance time windows: 100 hours/2 months for initial checks and at‑least‑one modification; 300 hours/12 months for all remaining modifications; installation ban effective 7 Feb 2009.","Applicability limited to five Arrius engine models but covers all serial numbers (wide applicability within those models).","Two notes add context (known helicopter types and reference to EASA AD) but do not add nested exceptions."],"plain_english_summary":"**What this directive does (mechanically)\n\n- It requires operators of Turbomeca Arrius 2B1, 2B1A, 2B2, 2K1 and 2K2 turbine engines to check the serial numbers of their Engine Electronic Control (EEC) units against the Appendix to Turbomeca Service Bulletin (SB) No. 319 73 2835 Update 1.\n- If both EEC units on a helicopter are listed in that Appendix, at least one listed unit must be modified immediately in accordance with the SB instructions.\n- All remaining listed (affected) EEC units must be modified according to the SB within a longer compliance window.\n- From 7 February 2009, any EEC with a serial number listed in the Appendix may not be fitted as a replacement spare unless it has been modified per the SB.\n- Later revisions of the SB that are approved by the European Aviation Safety Agency (EASA) are treated as acceptable for compliance. Modifications already done under the earlier SB dated 9 November 2006 are also accepted.\n\n**Who is affected\n\n- Aircraft operators and owners that have helicopters fitted with Turbomeca Arrius 2B1, 2B1A, 2B2, 2K1 or 2K2 engines (the AD notes installations on, for example, Eurocopter EC135 and Agusta A109).\n- Maintenance organisations (MROs) and technicians who perform engine/EEC inspections and modify or install EEC units.\n- Parts suppliers and inventories holding EEC spares with the listed serial numbers.\n\n**Deadlines (how quickly things must be done)\n\n- Requirement 1 & 2 (inspect serial numbers; if both units listed modify at least one): within 100 flight hours or two months, whichever comes first, after the Directive’s effective date.\n- Requirement 3 (modify all remaining affected EEC units): within 300 flight hours or 12 months, whichever comes first.\n- Requirement 4 (ban on installing unmodified listed spares): takes effect after 7 February 2009.\n\n**Why the rule exists (claimed safety problem)\n\n- The manufacturer reported that some tantalum capacitors inside certain EECs may have become embrittled during supplier acceptance testing. Embrittled capacitors can short circuit, and a short in an EEC could cause an in‑flight shutdown of one engine. The AD requires identification and modification of affected EECs to remove that risk (Requirement section; Background).\n\n**Practical effects, who pays and who decides\n\n- Operators bear the direct costs: time to inspect EEC serial numbers, labour to carry out the modifications, parts or modification kits if needed, and aircraft downtime while work is done (Requirements 1–3; Compliance times).\n- Maintenance organisations will perform the work and charge for labour and materials; if modification kits or OEM-only work are required, that concentrates aftermarket spend with the manufacturer or authorised shops.\n- The regulatory decision is imposed by the airworthiness authority (the Directive); operators must comply within the specified windows or be non‑compliant.\n\n**Implementation trade-offs, risks and market effects\n\n- Compliance cost and operational impact: short compliance windows for initial checks (100 hours / two months) can cause scheduling pressure; the longer window for completing all modifications (300 hours / 12 months) reduces immediate cost but still requires planning and possible temporary removal of aircraft from service.\n- Parts/availability risk: if modification requires OEM parts or limited-shop capability, operators may face longer downtime or higher prices.\n- Spare inventory effect: the ban on installing unmodified listed spares after 7 February 2009 forces operators and spares managers to either modify spares or take them out of service, creating an incentive to modify stock or purchase already‑modified units.\n- Competitive impact: if only the engine manufacturer or authorised agents can perform the modification, independent MROs may be disadvantaged; the SB being acceptable when revised by EASA reduces regulatory uncertainty for shops that follow approved revisions.\n- Enforcement and compliance burden: inspection of serial numbers and record‑keeping is straightforward but must be done across fleets; operators who already performed the earlier SB modification (9 November 2006) are explicitly accepted as compliant, which reduces duplication of work for some.\n\n**Net mechanism summary\n\n- The Directive identifies a specific hardware defect (tantalum capacitors in EECs) by serial number, mandates modification per an OEM service bulletin, sets short and medium compliance windows, and prohibits use of listed unmodified spares after a given date. Operators and MROs pay for and perform the work; regulators accept later SB revisions approved by EASA and prior compliant work.\n\n(Referenced: Requirements 1–4; Compliance times; Background; Notes on SB and EASA acceptance.)"},"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 is a standard, targeted Airworthiness Directive addressing a specific safety defect in specific engine models. The scope remains precisely limited to the identified capacitor defect in Arrius series EEC units. There is no evidence of scope creep; the directive does not expand beyond its original safety purpose of preventing in-flight engine shutdowns."},"complexity_factors":["Short, single-purpose directive with clear sequential requirements (only 4 numbered requirements)","Limited applicability scope (5 specific engine models, all serial numbers)","Single external reference document (Turbomeca Service Bulletin N°319 73 2835 Update 1) that contains the actual technical modification instructions","Simple conditional logic (if-then structure in Requirement 2)","Two-tier compliance deadlines based on flight hours vs calendar time, but clearly specified","No nested definitions section — terms like 'EEC' and 'TIS' (Time in Service) are standard aviation terminology","Grandfathering provision for modifications already done under earlier service bulletin version"],"plain_english_summary":"This CASA Airworthiness Directive mandates operators and maintainers of Turbomeca Arrius 2B-series engines (used in EC135, A109, etc.) to check and modify Engine Electronic Control (EEC) units that contain capacitors prone to short-circuiting and causing in-flight engine shutdowns. It requires timely inspections and hardware modifications, bans installation of unmodified spare EECs, and is legally mandatory to reduce the risk of engine failure and potential dual-engine loss."}},"importantCases":[],"_links":{"self":"/api/acts/ad-arrius-14-engine-electronic-control-units","history":"/api/acts/ad-arrius-14-engine-electronic-control-units/history","analysis":"/api/acts/ad-arrius-14-engine-electronic-control-units/analysis","conflicts":"/api/acts/ad-arrius-14-engine-electronic-control-units/conflicts","importantCases":"/api/acts/ad-arrius-14-engine-electronic-control-units/important-cases","documents":"/api/acts/ad-arrius-14-engine-electronic-control-units/documents"}}