{"id":"F2006B09038","name":"AD/DHC-2/20 - Control Column Torque Tubes - Inspection","slug":"ad-dhc-2-20-control-column-torque-tubes-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52742,"registerId":"commonwealth-F2006B09038-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-2/20 - Control Column Torque Tubes - Inspection","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)  DHC-2 (Beaver) Series Aeroplanes\n\n \n\nAD/DHC-2/20 Control Column Torque Tubes - Inspection 9/80\n\nApplicability: All models DHC-2 and DHC-2 Mk. III. Document:  De Havilland Aircraft of Canada SB No. 2/28.\n\nCompliance: Initially inspect within 25 hours time in service after 18 September 1980 and thereafter as noted in De Havilland Aircraft of Canada SB No. 2/28.\n\n \n\nBackground:  Three overseas operators have reported cracks in the horizontal torque tube at the base of the control column.\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\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive focuses on inspections of the horizontal control-column torque tube for all DHC-2 and DHC-2 Mk. III aircraft and references the manufacturer’s service bulletin for inspection technique and intervals. The scope as stated (inspect and then follow the SB) is consistent with the document’s stated purpose of responding to reported cracks; there is no material indication in the text that the directive’s scope was broadened or narrowed from that stated intent."},"complexity_factors":["Short, specific applicability (all DHC-2 and DHC-2 Mk. III) reduces ambiguity (Applicability).","Tight initial compliance window (inspect within 25 hours TIS after 18 September 1980) increases operational scheduling pressure (Compliance).","Substantive technical procedure and recurring intervals are delegated to an external manufacturer service bulletin (De Havilland SB No. 2/28), requiring users to obtain and follow that document (Document).","The AD gives a clear directive but contains no technical inspection method itself, so practical compliance depends on the SB’s level of detail and maintenance personnel’s ability to detect cracks (Document; Compliance).","Limited factual background (three overseas reports of cracking) supplies cause but not quantified risk, leaving judgment about urgency and follow-up workload to implementers (Background)."],"plain_english_summary":"What this instrument requires, mechanically\n\n- The directive orders owners/operators to inspect the control-column horizontal torque tube on specific De Havilland Beaver aeroplanes. The inspection must follow the procedures and intervals set out in the manufacturer's service bulletin (De Havilland Aircraft of Canada SB No. 2/28). (Document: De Havilland Aircraft of Canada SB No. 2/28)\n\n- The first inspection had to be completed within 25 hours time in service after 18 September 1980, and subsequent inspections are to be done on the schedule described in the manufacturer’s bulletin. (Compliance: Initially inspect within 25 hours time in service after 18 September 1980 and thereafter as noted in De Havilland Aircraft of Canada SB No. 2/28)\n\nWho is affected\n\n- All owners/operators of DHC-2 and DHC-2 Mk. III aeroplanes are covered. (Applicability: All models DHC-2 and DHC-2 Mk. III)\n\nWhy it was issued (official basis)\n\n- The directive records that three overseas operators reported cracks in the horizontal torque tube at the base of the control column. The inspection requirement follows that condition report. (Background: Three overseas operators have reported cracks in the horizontal torque tube at the base of the control column)\n\nPractical effects, incentives and costs\n\n- Who pays: aircraft owners/operators pay for inspections, any follow-up work, parts and downtime. The AD itself does not allocate funding. (Applicability; Compliance)\n\n- Who decides and how compliance is defined: the civil aviation authority issued the directive and made compliance dependent on following the manufacturer’s service bulletin (SB No. 2/28). The SB supplies the technical method and recurring interval after the initial 25‑hour requirement. (Document; Compliance)\n\n- Behavioural change demanded: operators must schedule and carry out an initial inspection within the short window (25 hours TIS from the stated date) and then follow whatever recurring inspection interval the manufacturer’s bulletin specifies. That requires operational planning to allocate maintenance hours and possible downtime. (Compliance)\n\n- Direct costs and opportunity costs: inspections consume labour time and may remove an aircraft from service for the inspection and any repairs identified. If cracks are found, parts replacement or additional maintenance will increase direct costs and extend downtime. (Compliance; Background)\n\n- Implementation and detection risk: the AD delegates technical detail to the manufacturer’s service bulletin. The effectiveness of the measure thus depends on the bulletin’s inspection technique and on maintenance personnel detecting cracks during those inspections. (Document; Compliance)\n\n- Effect on maintenance market and competition: the directive creates demand for inspection and any corrective work. Independent maintenance organisations and licensed engineers can perform inspections and repairs consistent with the SB, subject to existing regulatory licencing and certification requirements. (Document; Compliance)\n\nTrade-offs and administrative features\n\n- The directive trades a short-term compliance cost (inspections and potential repairs) for the stated objective of identifying reported cracking in a primary flight-control component. (Background; Compliance)\n\n- The AD relies on an external technical document (the manufacturer’s SB) for the how/when details; that reduces technical detail in the AD but increases dependency on the SB being available and clear. (Document)\n\n- The compliance window for the initial inspection (25 hours TIS after 18 September 1980) is brief, which concentrates the immediate workload on operators of affected aircraft. (Compliance)\n\nSummary statements of who pays, who decides, and likely behavioural change\n\n- Owners/operators pay for inspections and repairs. (Applicability; Compliance)\n- The civil aviation authority issued the directive and requires compliance by reference to the manufacturer’s service bulletin. (Document; Compliance)\n- Operators must inspect the torque tube within the specified short initial period, then continue inspections per the manufacturer’s schedule; this will change maintenance scheduling and create demand for inspection/repair work. (Compliance; Document)\n\nSource citations: Applicability; Document; Compliance; Background."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original purpose of mandating inspection of control column torque tubes."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 1 defined term implicitly referenced (Service Bulletin)","No cross-references to other legislation beyond the enabling Civil Aviation Regulations 1998","Simple conditional logic: single compliance trigger (25 hours time in service) with reference to external technical document","No nested exceptions or complex definitional sections","Single applicability criterion (aircraft model)","Straightforward background-to-action structure"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998.\n\n**What it does:**\nIt requires owners and operators of **De Havilland DHC-2 \"Beaver\" aircraft** (including the Mk. III variant) to inspect the **control column torque tubes** — specifically the horizontal torque tube at the base of the control column — for cracks.\n\n**Who it affects:**\n- Owners and operators of all DHC-2 and DHC-2 Mk. III aeroplanes\n- Maintenance organisations servicing these aircraft\n\n**What must be done:**\n- **First inspection:** Must be completed within 25 hours of flying time after 18 September 1980\n- **Ongoing inspections:** Must follow the schedule set out in De Havilland Service Bulletin No. 2/28 (a technical notice from the manufacturer)\n\n**Why it matters:**\nThree overseas operators found cracks in this part. The control column torque tube is critical to flight control — if it fails, the pilot could lose control of the aircraft. This AD prevents accidents by catching fatigue cracks before they cause catastrophic failure.\n\n**Key point:** This is not optional. \"Compliance\" means you must do it or the aircraft cannot legally fly."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-2-20-control-column-torque-tubes-inspection","history":"/api/acts/ad-dhc-2-20-control-column-torque-tubes-inspection/history","analysis":"/api/acts/ad-dhc-2-20-control-column-torque-tubes-inspection/analysis","conflicts":"/api/acts/ad-dhc-2-20-control-column-torque-tubes-inspection/conflicts","importantCases":"/api/acts/ad-dhc-2-20-control-column-torque-tubes-inspection/important-cases","documents":"/api/acts/ad-dhc-2-20-control-column-torque-tubes-inspection/documents"}}