{"id":"F2006B06895","name":"AD/SD3-60/49 - Engine Controls - Inspection and Replacement","slug":"ad-sd3-60-49-engine-controls-inspection-and-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114775,"registerId":"commonwealth-F2006B06895-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SD3-60/49 - Engine Controls - Inspection and Replacement","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)  \nShort SD3-60 Series Aeroplanes\n\nAD/SD3-60/49 Engine Controls \\- Inspection and Replacement 1/99\n\nApplicability: All Short Brothers SD3-60 Sherpa aircraft.\n\nRequirement: Inspect and replace as necessary all power control cables and pulleys in accordance with Short Brothers Service Bulletin SD3-60 Sherpa - 76-1.\n\nNote: UK CAA AD 004-07-98 dated 22 October 1998 refers.\n\nCompliance: At the next scheduled maintenance programme ‘D’ check or 1200 flight hours after the effective date of this Directive, whichever is the sooner.\n\nThis Airworthiness Directive becomes effective on 28 January 1999.\n\nBackground: Experience has shown that the 7 x 7 power control cables are subject to breakage of wires. This Service Bulletin introduces more flexible cables which are of 7 x 19 construction and requires the changing of certain pulleys to improve the reliability of the cables.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The Directive does not expand or narrow the population of affected aircraft beyond what it states: it applies to all Short Brothers SD3-60 Sherpa aircraft (Applicability). It imposes an inspection-and-replacement requirement in accordance with the manufacturer’s Service Bulletin (Requirement) and sets a specific compliance window (Compliance). There is no text in the Directive that purports to change the regulated scope beyond this applicability and these required actions."},"complexity_factors":["Narrow applicability: applies only to Short Brothers SD3-60 Sherpa aircraft (Applicability).","Delegation to external technical document: mandatory compliance is defined by a manufacturer Service Bulletin (Requirement).","Technical specificity about cable construction (7 x 7 to 7 x 19) and pulley replacement introduces parts and tooling needs (Background; Requirement).","Discretion in application: the instruction to \"inspect and replace as necessary\" requires maintenance judgement, creating variability in execution (Requirement).","Timing constraint tied to scheduled maintenance (‘D’ check) or a flight-hour limit creates scheduling and opportunity-cost considerations (Compliance)."],"plain_english_summary":"What this directive does mechanically:\n\n- It requires that all Short Brothers SD3-60 Sherpa aeroplanes have their power control cables and pulleys inspected and replaced where necessary, following the technical steps set out in Short Brothers Service Bulletin SD3-60 Sherpa - 76-1 (Requirement).\n- The work must be done at the aircraft's next scheduled maintenance programme ‘D’ check or within 1200 flight hours after the Directive’s effective date (28 January 1999), whichever comes sooner (Compliance; Effective date).\n\nWhy this change was issued (claimed purpose) and what it changes:\n\n- The Directive states the reason: the existing power control cables of 7 x 7 construction have shown wire breakage; the Service Bulletin replaces them with more flexible 7 x 19 cables and requires replacement of certain pulleys to improve cable reliability (Background). That is the safety-improvement claim the Directive cites.\n\nWho it affects and who pays:\n\n- Applicability: every Short Brothers SD3-60 Sherpa aircraft (Applicability).\n- The direct cost and work fall to the aircraft owners/operators (they must schedule the inspection/replacement and obtain parts and labour). The regulator (Civil Aviation Safety Authority) has mandated the action through the Airworthiness Directive.\n\nHow it works in practice (implementation mechanics, incentives and burdens):\n\n- The Directive delegates the technical method to the manufacturer’s Service Bulletin (Requirement). That means maintenance providers must follow the SB’s instructions when doing inspections and replacements.\n- The phrase “inspect and replace as necessary” leaves a maintenance judgement about what needs replacing to the inspector or maintenance organisation (Requirement). That creates a compliance judgement point: if a cable or pulley is judged serviceable, it may not be replaced; if judged unserviceable, it must be.\n- Timing ties compliance to an existing maintenance milestone (the ‘D’ check) or a flight-hour limit (1200 hours) (Compliance). Operators who would otherwise defer this work may need to bring it forward, creating scheduling and opportunity costs (downtime, earlier procurement of parts).\n- The work requires replacement components (7 x 19 cables and certain pulleys). Operators therefore must source those parts and contract or carry out the maintenance, which can affect maintenance costs and aircraft availability.\n\nTrade-offs, risks and practical effects (mechanisms, not value judgments):\n\n- Trade-off presented by the Directive: the regulator and manufacturer propose that replacing 7 x 7 cables with 7 x 19 cables and changing pulleys will improve reliability (Background). The trade-off for operators is paying for inspections/replacements and incurring downtime upfront in return for the claimed reduction in cable failure risk.\n- Compliance burden is concentrated on the relatively small population of SD3-60 Sherpa operators (Applicability). The technical work is delegated to maintenance organisations following the Service Bulletin (Requirement), so independent MROs that can comply with the SB can perform the work.\n- Implementation risk centers on accurate inspection judgements, parts availability and scheduling around the D-check/1200-hour compliance window (Requirement; Compliance).\n\nKey citations from the Directive text: Applicability; Requirement (reference to Service Bulletin SD3-60 Sherpa - 76-1); Compliance (next D-check or 1200 flight hours); Background (7 x 7 wire breakage and introduction of 7 x 19 cables and pulley changes)."},"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 cable and pulley replacement."},"complexity_factors":["Single, specific aircraft type (Short SD3-60 Sherpa)","Clear, single requirement: inspect and replace per referenced Service Bulletin","Simple compliance deadline (next 'D' check or 1,200 hours)","No defined terms section","No cross-references to other legislation beyond the referenced UK CAA AD and manufacturer Service Bulletin","Straightforward conditional logic (whichever is sooner)","Total length: approximately 150 words"],"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 aircraft: the **Short Brothers SD3-60 Sherpa**.\n\n**What it does:**\n- Requires owners and operators of these aircraft to **inspect and replace** certain engine control cables and pulleys\n- The old cables (7×7 construction) have been breaking, so they must be swapped for more flexible **7×19 cables**\n- Some pulleys must also be changed to work properly with the new cables\n\n**Who must follow this:**\n- Anyone who owns or operates a Short SD3-60 Sherpa aircraft in Australia\n- Maintenance organisations servicing these aircraft\n\n**When it must be done:**\n- By the next major 'D' check (a thorough maintenance inspection), **or**\n- Within 1,200 flight hours after 28 January 1999 — whichever comes first\n\n**Why it matters:**\nBroken engine control cables are extremely dangerous — they could cause loss of engine power or control. This directive prevents accidents by forcing operators to upgrade to more reliable components before the old ones fail."}},"importantCases":[],"_links":{"self":"/api/acts/ad-sd3-60-49-engine-controls-inspection-and-replacement","history":"/api/acts/ad-sd3-60-49-engine-controls-inspection-and-replacement/history","analysis":"/api/acts/ad-sd3-60-49-engine-controls-inspection-and-replacement/analysis","conflicts":"/api/acts/ad-sd3-60-49-engine-controls-inspection-and-replacement/conflicts","importantCases":"/api/acts/ad-sd3-60-49-engine-controls-inspection-and-replacement/important-cases","documents":"/api/acts/ad-sd3-60-49-engine-controls-inspection-and-replacement/documents"}}