{"id":"F2006B10322","name":"AD/GROB 115/3 - Steering Damper Bushes","slug":"ad-grob-115-3-steering-damper-bushes","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56076,"registerId":"commonwealth-F2006B10322-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/GROB 115/3 - Steering Damper Bushes","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)  Grob G115 Series Aeroplanes\n\n \n\nAD/GROB 115/3 Steering Damper Bushes 3/91\n\nApplicability: Model Grob G115A with serial numbers 8090 through 8109.\n\n \n\nRequirement: Action in accordance with the technical requirements of German LBA AD 90-344.\n\n \n\nNote: Grob SB TM 1078-17 refers.\n\n \n\nCompliance: Unless already accomplished; before the next flight after 21 March 1991.\n\n \n\nBackground: During the manufacture of the G 115A, some oversize bushes were installed in the steering damper 115-4220. Under certain circumstances this can cause the rudder to jam.\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\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive maintains a narrowly targeted scope: it applies only to Grob G115A aircraft with serial numbers 8090–8109 and requires those aircraft to be inspected and rectified in accordance with the German LBA AD 90-344. It does not expand applicability beyond the specified serial numbers or change the nature of the required technical action; it simply makes compliance mandatory under CASA with a specified deadline (see \"Applicability\", \"Requirement\", \"Compliance\")."},"complexity_factors":["Very narrow applicability: only Grob G115A serial numbers 8090–8109 (\"Applicability\").","Dependence on external technical documents (German LBA AD 90-344) rather than full technical steps in the AD itself (\"Requirement\").","Reference to manufacturer service bulletin for related guidance (Grob SB TM 1078-17) increases necessary document retrieval (\"Note\").","Short, firm compliance deadline (before next flight after 21 March 1991) imposes immediate operational constraints (\"Compliance\").","Safety-critical technical subject (steering damper bushes, potential rudder jam) requires competent maintenance actions rather than routine administrative compliance (\"Background\")."],"plain_english_summary":"What this instrument requires (mechanical change)\n\n- The Civil Aviation Safety Authority (CASA) issued an airworthiness directive that requires owners/operators of Grob G115A aeroplanes with serial numbers 8090 through 8109 to carry out the technical actions set out in the German LBA Airworthiness Directive 90-344 (\"Requirement\").\n- The directive points to Grob Service Bulletin TM 1078-17 as related information (\"Note\").\n- The required work must be done before the next flight after 21 March 1991 unless the work has already been completed (\"Compliance\").\n\nWhy the rule exists (official rationale)\n\n- The directive explains that during manufacture some oversize bushes were fitted in the steering damper part 115-4220, and under certain circumstances those oversize bushes can cause the rudder to jam (\"Background\"). The stated purpose is to eliminate that hazard by inspecting and/or correcting the steering damper in the affected aeroplanes.\n\nWho this affects and who decides\n\n- Who pays: The owners/operators of the affected Grob G115A aircraft (serial numbers 8090–8109) bear the cost of compliance: inspection, parts, labour and any resulting downtime (see \"Applicability\" and \"Compliance\").\n- Who decides/acts: CASA issues the directive; the owners/operators (and their maintenance organisations) must carry out the technical measures specified in the referenced German LBA AD and follow the Grob service information where applicable (see \"Requirement\" and \"Note\").\n\nWhat behaviour changes and why that matters\n\n- Aircraft movement: Affected aircraft cannot be flown after the compliance date until the required inspections/rectifications are done (\"Compliance\"). That changes owner/operator choices about scheduling, maintenance and aircraft availability.\n- Maintenance practice: Maintenance organisations must inspect the steering damper 115-4220 and take the corrective steps required by the referenced technical document (\"Requirement\").\n\nCosts, incentives, trade-offs and implementation considerations\n\n- Direct costs and downtime: Compliance imposes direct maintenance costs (inspection, possible replacement of bushes or damper units) and opportunity costs from aircraft downtime. Those costs fall on the owners/operators (\"Applicability\", \"Compliance\").\n- Concentrated benefit, concentrated cost: The safety benefit—reducing the risk of rudder jam—accrues directly to operators/crew/passengers of the specific aircraft listed (\"Background\"). The compliance cost is likewise concentrated on the same owners/operators.\n- Reliance on an external technical standard: The directive requires action in accordance with German LBA AD 90-344 rather than reproducing technical steps in full (\"Requirement\"). This creates a dependence on that external document and on the Grob service bulletin referenced (\"Note\") for the exact technical method, which means operators must obtain and follow those foreign/manufacturer documents to comply.\n- Limited regulatory discretion for operators: The AD sets a mandatory requirement and a firm compliance deadline; it does not leave substantive discretion about whether to act. Operational discretion remains only in scheduling the work and in selecting an approved maintenance provider to perform it (\"Requirement\", \"Compliance\").\n- Implementation risks: Possible practical issues include locating correct spare parts or a maintenance provider able to carry out the prescribed work, and ensuring the referenced documents are obtained and followed precisely.\n\nNet operational effect (mechanical summary)\n\n- In practice, affected aircraft must be inspected and any necessary corrective work performed on the steering damper bushes before the next flight after 21 March 1991. The stated aim is to remove the risk of rudder jam caused by oversize bushes installed during manufacture (\"Background\")."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-limited safety directive addressing a specific manufacturing defect in a small fleet of aircraft. It has not expanded beyond its original purpose of mandating a single safety fix."},"complexity_factors":["Very short document (under 200 words)","Only 4 operative paragraphs (Applicability, Requirement, Note, Compliance)","Single, specific applicability criterion (one model, narrow serial number range)","No defined terms section","No cross-references to other legislation beyond one external German AD and one manufacturer service bulletin","Simple unconditional directive with single compliance deadline","No exceptions, exemptions, or conditional logic"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) issued by Australia's Civil Aviation Safety Authority for a specific type of light aircraft.\n\n**What it does:**\nOrders owners and operators of **Grob G115A aeroplanes** with serial numbers 8090 through 8109 to fix a manufacturing defect in the steering damper bushes (small components that help control the rudder).\n\n**The problem:**\nSome aircraft were built with oversize bushes in the steering damper. This defect can cause the **rudder to jam** during flight — a serious safety risk.\n\n**What must be done:**\n- Follow the technical instructions in **German LBA AD 90-344** (Germany's aviation safety authority issued the original fix)\n- Reference **Grob Service Bulletin TM 1078-17** for guidance\n- Complete the repair **before the next flight after 21 March 1991**\n\n**Who it affects:**\nOwners and operators of approximately 20 specific Grob G115A training aircraft (serial numbers 8090–8109).\n\n**Why it matters:**\nRudder jam can cause loss of directional control. This directive ensures the defect is corrected before the aircraft flies again, preventing potential accidents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-grob-115-3-steering-damper-bushes","history":"/api/acts/ad-grob-115-3-steering-damper-bushes/history","analysis":"/api/acts/ad-grob-115-3-steering-damper-bushes/analysis","conflicts":"/api/acts/ad-grob-115-3-steering-damper-bushes/conflicts","importantCases":"/api/acts/ad-grob-115-3-steering-damper-bushes/important-cases","documents":"/api/acts/ad-grob-115-3-steering-damper-bushes/documents"}}