{"id":"F2006B04808","name":"AD/BO 105/5 - Tandem Hydraulic Units - Piston Rods","slug":"ad-bo-105-5-tandem-hydraulic-units-piston-rods","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44596,"registerId":"commonwealth-F2006B04808-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/BO 105/5 - Tandem Hydraulic Units - Piston Rods","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)  \nEurocopter BO 105 Series Helicopters\n\nAD/BO 105/5 Tandem Hydraulic Units \\- Piston Rods 8/86\n\nApplicability: All model BO 105 helicopters with less than 1200 hours total time in service fitted with Teledyne Hydra-Power tandem hydraulic units P/N 105-45021 with S/Nos: 1012, 1014 to 1019, 1021, 1023, 1027 to 1030, 1032, 1034, 1035, 1037, 1038, 1040,\n\n1041, 1043 to 1046, 1049, 1056, 1057, 1062, 1064 to 1066, 1069, 1071, 1075, 1091,\n\n1093, 1101, 1104, 1109, 1113, 1119, 1121, 1123, 1126, 1127, 1136, 1160 and 1161.\n\nRequirement: Action in accordance with MBB SB 40-19, or SB 40-21.\n\nCompliance: Inspect at 600 hours total time in service and again at 1200 hours total time in service. Background: Cracks have been found on piston rods of Teledyne Hydra-Power actuators. LBA AD\n\n75-172/2 MBB also refers.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted airworthiness directive addressing a specific safety defect in specific aircraft components. It has not expanded beyond its original purpose of mandating inspections for cracked piston rods."},"complexity_factors":["Single, specific technical requirement (inspect at two time intervals)","Limited applicability scope (one helicopter model, specific serial numbers)","No nested exceptions or conditional logic","Only 2 cross-references (to manufacturer service bulletins)","Short document (approximately 150 words)","Clear compliance deadline (hours-based, not calendar-based)"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific maintenance actions on certain helicopters.\n\n**What it does:**\n- Orders inspections of **tandem hydraulic units** (a type of aircraft component that helps control the helicopter) on specific **Eurocopter BO 105 helicopters**\n- Requires helicopter operators to inspect these hydraulic units when the aircraft reaches **600 flight hours** and again at **1,200 flight hours**\n- The inspections must follow specific manufacturer service bulletins (MBB SB 40-19 or SB 40-21)\n\n**Who it affects:**\n- Owners and operators of BO 105 helicopters with **less than 1,200 total flight hours**\n- Only applies to helicopters fitted with specific Teledyne Hydra-Power hydraulic units with particular serial numbers (listed in the directive)\n\n**Why it matters:**\n- **Safety critical:** Cracks have been discovered in the piston rods (the moving parts) of these hydraulic actuators\n- If left unchecked, these cracks could cause hydraulic failure, potentially leading to loss of aircraft control\n- Compliance is **legally mandatory** — operators cannot fly these helicopters without completing the required inspections"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Based solely on the AD text provided, the scope is clear and limited: it applies to BO 105 helicopters with less than 1,200 hours total time in service that are fitted with Teledyne Hydra‑Power tandem hydraulic units P/N 105-45021 with the listed serial numbers. The AD requires inspections at 600 and 1,200 hours in accordance with MBB SB 40-19 or SB 40-21. There is no indication in the supplied text that the AD broadens or narrows that scope beyond what is stated."},"complexity_factors":["Targeted scope based on specific part number (P/N 105-45021) and a long list of serial numbers creates administrative identification work (Applicability).","Fixed inspection intervals tied to aircraft total time in service (600 and 1,200 hours) require scheduling and record checks (Compliance).","Technical execution and corrective measures are delegated to external documents (MBB SB 40-19 and SB 40-21), creating dependency on those service bulletins (Requirement).","Potential for follow-on repairs if cracks are found introduces operational disruption risk (Background + Requirement).","Cross-reference to other authorities (LBA AD 75-172/2 MBB also refers) increases the number of documents to consult (Background)."],"plain_english_summary":"This AD requires owners/operators of certain BO 105 helicopters (those with Teledyne Hydra‑Power tandem hydraulic units P/N 105‑45021 and under 1,200 hrs TIS) to have piston rods inspected at 600 and 1,200 hours TIS in accordance with MBB SB 40‑19 or SB 40‑21. It targets known rod cracking, shifts inspection cost and scheduling onto operators, and obliges maintenance providers to follow the referenced service bulletins for any corrective work."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bo-105-5-tandem-hydraulic-units-piston-rods","history":"/api/acts/ad-bo-105-5-tandem-hydraulic-units-piston-rods/history","analysis":"/api/acts/ad-bo-105-5-tandem-hydraulic-units-piston-rods/analysis","conflicts":"/api/acts/ad-bo-105-5-tandem-hydraulic-units-piston-rods/conflicts","importantCases":"/api/acts/ad-bo-105-5-tandem-hydraulic-units-piston-rods/important-cases","documents":"/api/acts/ad-bo-105-5-tandem-hydraulic-units-piston-rods/documents"}}