{"id":"F2006B06861","name":"AD/SD3-60/18 - Take-Off Trim Range","slug":"ad-sd3-60-18-take-off-trim-range","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114739,"registerId":"commonwealth-F2006B06861-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SD3-60/18 - Take-Off Trim Range","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)  Short SD3-60 Series Aeroplanes\n\n \n\nAD/SD3-60/18 Take-Off Trim Range 12/86 DM\n\nApplicability: All Shorts SD3-60, fitted with Pratt and Whitney PT6A-65R engines, and Shorts\n\nSD3-60 with serial numbers SH3601 to SH3685, fitted with Pratt and Whitney PT6A- 65AR engines.\n\n \n\nRequirement: Action in accordance with either Shorts Service Bulletin:\n\n \n\n1. SD360-27-10 Revision No. 1 for PT6A-65R engines; or\n\n\n \n\n2.    SD360-27-11 Revision No. 2 for PT6A-65AR Engines. Compliance: Prior to 30 November 1986.\n\nBackground:  Operational experience has found that excessive control column force is required during take-off under certain conditions.\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’s scope — to require the manufacturer’s corrective actions for specific SD3-60 aircraft to address excessive control column force during take-off — is presented directly and without additional qualifications in the text. The instrument applies to the aircraft identified and requires compliance with the named service bulletins by the stated date (Applicability; Requirement; Compliance). There is no indication within the text that the scope was altered from the original corrective purpose described in the Background."},"complexity_factors":["Narrow applicability: affects only SD3-60 airframes with two specific engine fitments or specified serial numbers (Applicability).","Single-prescribed remedy: mandates following one of two manufacturer service bulletins rather than multiple regulatory pathways (Requirement).","Fixed compliance date creates scheduling/implementation pressure but no phased compliance options (Compliance).","Technical detail outsourced to manufacturer documents increases dependence on external technical material (Requirement).","Regulatory clarity is high (clear action, clear affected population), but technical implementation requires certified maintenance expertise (Requirement)."],"plain_english_summary":"What this instrument does\n\n- This is an airworthiness directive that requires specific Shorts SD3-60 aeroplanes to be modified or inspected in accordance with a manufacturer’s service bulletin because an operational problem was found. (See \"Applicability\" and \"Requirement\".)\n\nWho it affects\n\n- Owners and operators of Shorts SD3-60 aircraft fitted with Pratt & Whitney PT6A-65R engines, and those SD3-60 aircraft with serial numbers SH3601 to SH3685 fitted with Pratt & Whitney PT6A-65AR engines. (See \"Applicability\".)\n\nWhat it requires, mechanically\n\n- Operators must carry out the actions specified in the relevant Shorts Service Bulletin: either SD360-27-10 Revision No. 1 (for PT6A-65R) or SD360-27-11 Revision No. 2 (for PT6A-65AR). The directive does not reproduce the technical steps; it makes following the stated service bulletin compulsory. (See \"Requirement\".)\n\nWhen it must be done\n\n- The directive set a compliance deadline: the required actions had to be completed prior to 30 November 1986. (See \"Compliance\".)\n\nWhy the action is required (official purpose)\n\n- The stated reason is that operational experience showed excessive control column force was needed during take-off under certain conditions. The directive therefore mandates the manufacturer’s corrective action to address that condition. (See \"Background\".)\n\nWho pays, who decides, and what changes in behaviour\n\n- Who pays: aircraft owners/operators pay for the maintenance work, parts and labour needed to implement the service bulletin instructions (implied by the Requirement referencing the manufacturer’s service bulletins). (See \"Requirement\".)\n- Who decides: the Civil Aviation Safety Authority issued the directive (it appears in the Schedule of Airworthiness Directives under the Civil Aviation Regulations), and the technical details and actions are specified by the aircraft manufacturer’s service bulletins. Maintenance organisations carrying out the work make the technical judgments required to comply with the service bulletin. (See header and \"Requirement\".)\n- Behavioural change required: affected operators must schedule and complete the mandated maintenance or modification work by the compliance date; maintenance organisations must follow the specific service bulletin instructions when performing the work. (See \"Requirement\" and \"Compliance\".)\n\nPractical trade-offs, costs and implementation notes (source-grounded)\n\n- Compliance cost and burden: the directive imposes a concrete compliance obligation on a defined subset of aircraft; those operators must allocate resources (time, labour, possibly parts) to perform the service bulletin tasks before the stated deadline. The directive does not state cost, so operators will bear whatever direct costs arise from following the service bulletin. (See \"Requirement\" and \"Compliance\".)\n- Reliance on manufacturer instructions: the AD delegates the technical solution to the manufacturer’s service bulletin. This concentrates the technical specification in the manufacturer’s document and makes effective compliance depend on availability and clarity of that bulletin. (See \"Requirement\".)\n- Enforcement and discretion: the regulator prescribes compliance with a specified technical document; the technical discretion to implement that document lies with certificated maintenance organisations following the bulletin. The AD itself does not describe alternative compliance methods or discretionary exemptions. (See \"Requirement\".)\n- Timing risk: a fixed compliance date means operators needed to plan and complete the work by that date; the AD does not provide staged deadlines or extensions within its text. (See \"Compliance\".)\n\nLimitations of this summary\n\n- The directive references specific manufacturer service bulletins for the technical remedy; the exact maintenance tasks and any parts or performance effects are found only in those service bulletins, which are not reproduced in this instrument. (See \"Requirement\".)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope — addressing a specific flight control issue on a specific aircraft type. There is no evidence of scope creep; it remains a targeted safety intervention for the identified trim system defect."},"complexity_factors":["Single, specific aircraft type with narrow applicability criteria (two engine variants plus serial number range)","Only two compliance pathways (alternative service bulletins based on engine type)","No defined terms section — uses standard aviation terminology","Single deadline with no conditional extensions or exceptions","No cross-references to other legislation or regulations beyond the parent Civil Aviation Regulations 1988","Background explanation provided in plain language","Total length: approximately 150 words of substantive content"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It requires specific fixes to a particular type of aircraft to prevent dangerous flight conditions.\n\n**What it does:**\n- Orders owners and operators of **Shorts SD3-60 aircraft** (a twin-turboprop regional airliner) to modify the take-off trim system\n- Applies to two specific engine variants: Pratt & Whitney PT6A-65R engines, and PT6A-65AR engines on aircraft with serial numbers SH3601 to SH3685\n\n**Why it matters:**\n- **The safety problem:** Pilots were experiencing **excessive control column force during take-off** under certain conditions — meaning the aircraft was physically hard to control when leaving the ground, which could lead to loss of control or runway accidents\n- **The fix:** Operators must follow specific manufacturer service bulletins (SD360-27-10 or SD360-27-11 depending on engine type) to correct the trim range settings\n- **The deadline:** Compliance was required before 30 November 1986\n\n**Who it affects:**\n- Airlines and operators flying Shorts SD3-60 aircraft in Australia\n- Maintenance organisations servicing these aircraft\n\nThis is a **retrospective safety mandate** — it applies to existing aircraft already in service, not just new ones."}},"importantCases":[],"_links":{"self":"/api/acts/ad-sd3-60-18-take-off-trim-range","history":"/api/acts/ad-sd3-60-18-take-off-trim-range/history","analysis":"/api/acts/ad-sd3-60-18-take-off-trim-range/analysis","conflicts":"/api/acts/ad-sd3-60-18-take-off-trim-range/conflicts","importantCases":"/api/acts/ad-sd3-60-18-take-off-trim-range/important-cases","documents":"/api/acts/ad-sd3-60-18-take-off-trim-range/documents"}}