{"id":"F2006B04803","name":"AD/BO 105/14 - Dual Hydraulic System Switch Over","slug":"ad-bo-105-14-dual-hydraulic-system-switch-over","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44591,"registerId":"commonwealth-F2006B04803-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BO 105/14 - Dual Hydraulic System Switch Over","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Eurocopter BO 105 Series Helicopters\n\n \n\nAD/BO 105/14 Dual Hydraulic System Switch Over 10/89\n\nDM\n\nApplicability:  All model BO 105 helicopters with tandem hydraulic units P/N 105-45028 having valve body manifolds D133-756E, D133-756, ZE1-126-1, ZE2-126-1 or ZE2-126 installed in either No. 1 or 2 hydraulic system.\n\n \n\nRequirement: Action in accordance with MBB Alert Service Bulletin No ASB-BO 105-40-102.\n\n \n\nNote: LBA AD 89-123 refers.\n\n \n\nCompliance: Within 50 hours time in service after 25 August 1989 or by 30 September 1989, whichever occurs first.\n\n \n\nBackground:  Due to possible excessive wear in the servo connecting components a functional test of the hydraulic system switch over is required.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD, as written, applies to a clearly defined set of BO 105 helicopters with specified tandem hydraulic unit and valve body manifold types and requires action per a named manufacturer service bulletin within a defined short time window. The text does not indicate any extension, narrowing, or amendment of scope beyond that stated applicability and the stated purpose (Applicability; Requirement; Compliance; Background)."},"complexity_factors":["Narrow technical applicability (specific helicopter model and specified part numbers) — reduces scope complexity (Applicability).","Single mandatory action is required: follow a named manufacturer service bulletin — straightforward instruction but depends on an external technical document (Requirement).","Short, fixed compliance window creates scheduling pressure and operational complexity for affected operators (Compliance).","Technical content (hydraulic system functional test) requires specialist maintenance capability and correct interpretation of the service bulletin — adds practical implementation complexity (Requirement; Background).","Limited procedural discretion in the AD itself (it prescribes following the service bulletin), so legal complexity is low though operational dependency on manufacturer documentation raises implementation risk (Requirement)."],"plain_english_summary":"### What this directive does\n\nThis Airworthiness Directive (AD/BO 105/14) requires operators of certain BO 105 helicopters to carry out a specific action described by the manufacturer. The AD applies where a tandem hydraulic unit part number 105-45028 has a valve body manifold of type D133-756E, D133-756, ZE1-126-1, ZE2-126-1 or ZE2-126 installed in either the No. 1 or No. 2 hydraulic system (Applicability). The required action is to follow the procedures in MBB Alert Service Bulletin No ASB-BO 105-40-102 (Requirement). The stated reason is a possible excessive wear in servo connecting components, so a functional test of the hydraulic system switch over is required (Background). The work must be done within 50 hours time in service after 25 August 1989 or by 30 September 1989, whichever comes first (Compliance).\n\n### Who it affects\n\n- Owners and operators of all-model BO 105 helicopters that have the listed tandem hydraulic unit and valve body manifold types installed in either hydraulic system (Applicability).\n- Maintenance organisations and technicians who perform the functional test and any follow-up maintenance required by the service bulletin (Requirement).\n\n### Why it matters (mechanics and consequences)\n\n- The AD obliges affected operators to carry out the manufacturer-prescribed functional test to check hydraulic system switch-over operation (Requirement). The AD frames this as a response to possible excessive wear in servo connecting components that could affect that switch-over (Background).\n- Who pays: the helicopter owner/operator bears the direct cost of performing the test and any corrective maintenance discovered by that test (Applicability; Requirement; Compliance).\n- Who decides: the Civil Aviation Safety Authority issued the directive and prescribes the action to be taken by reference to the manufacturer’s service bulletin (header; Requirement).\n- Compliance burden and timing: the AD sets a short, fixed compliance window — 50 flight hours after 25 August 1989 or by 30 September 1989, whichever is earlier — creating an immediate maintenance scheduling requirement for affected aircraft (Compliance).\n- Implementation dependencies and risks: the AD requires work “in accordance with” a specific MBB Alert Service Bulletin (Requirement). That makes correct implementation dependent on access to and correct application of the manufacturer’s procedures and any materials or parts those procedures require.\n\n### Trade-offs, incentives and operational effects (source-grounded)\n\n- Safety vs cost: the stated purpose is to detect or prevent failures caused by worn servo connecting components (Background). Meeting that safety objective imposes immediate time and financial costs on affected operators (Compliance; Requirement).\n- Operational disruption: operators must schedule the functional test within the tight compliance window, which may cause aircraft downtime and reallocation of maintenance resources (Compliance; Requirement).\n- Market and competition effects (limited to what the AD specifies): the AD requires following a manufacturer service bulletin. The text does not specify who must perform the work, so any appropriately authorised maintenance organisation could perform the test, but operators will incur whatever market price the maintenance provider charges for the test and any necessary repairs (Requirement).\n\n### Concentration of benefits and costs\n\n- Benefits (reduced risk from the specific servo component wear) accrue to pilots, passengers and aircraft owners who operate the affected helicopters; those benefits are concentrated on operators of helicopters with the listed parts (Applicability; Background).\n- Costs are borne directly and immediately by those same operators through the required maintenance and any corrective work discovered by the test (Requirement; Compliance).\n\n### Implementation and discretion\n\n- The AD prescribes a mandatory action and a fixed compliance window; it gives limited operational discretion beyond following the referenced service bulletin (Requirement; Compliance).\n- The AD references an external document (MBB Alert Service Bulletin No ASB-BO 105-40-102). Correctness of implementation therefore depends on following that manufacturer document exactly (Requirement). The AD also notes a related foreign AD (LBA AD 89-123) but does not change the required action (Note).\n\n(References in parentheses indicate the part of the AD text that supports each point: Applicability; Requirement; Compliance; Background; Note.)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive issued in 1989 for a specific technical issue. It has not expanded beyond its original purpose of addressing wear in hydraulic servo components for BO 105 helicopters."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 5 defined part numbers in the applicability section","Single requirement referencing an external technical document (the service bulletin)","Simple compliance deadline structure (whichever occurs first of two dates)","No nested exceptions, conditional logic, or cross-references to other legislation","Straightforward background explanation without technical sub-clauses"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific helicopters.\n\n**What it does:**\nOrders owners and operators of certain **Eurocopter BO 105 helicopters** to perform a specific safety check on their **dual hydraulic systems**. The check involves testing whether the backup hydraulic system properly takes over if the main one fails (this is what \"switch over\" means).\n\n**Who it affects:**\nAnyone who owns or operates BO 105 helicopters that have specific tandem hydraulic units installed (identified by part numbers 105-45028 with particular valve body manifolds). This applies whether the unit is in hydraulic system No. 1 or No. 2.\n\n**Why it matters:**\nThere was a risk of **excessive wear in the servo connecting components** — parts that help control the helicopter's flight surfaces. If these wear out, the backup hydraulic system might not engage when needed, potentially causing loss of flight control. The directive requires following a specific manufacturer's service bulletin (MBB Alert Service Bulletin No ASB-BO 105-40-102) to check this.\n\n**When it had to be done:**\nOperators had to complete this check within **50 flight hours after 25 August 1989**, or by **30 September 1989** — whichever came first.\n\n**Key point:** This is a **mandatory compliance** document. Ignoring it would breach civil aviation regulations and could ground the aircraft."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bo-105-14-dual-hydraulic-system-switch-over","history":"/api/acts/ad-bo-105-14-dual-hydraulic-system-switch-over/history","analysis":"/api/acts/ad-bo-105-14-dual-hydraulic-system-switch-over/analysis","conflicts":"/api/acts/ad-bo-105-14-dual-hydraulic-system-switch-over/conflicts","importantCases":"/api/acts/ad-bo-105-14-dual-hydraulic-system-switch-over/important-cases","documents":"/api/acts/ad-bo-105-14-dual-hydraulic-system-switch-over/documents"}}