{"id":"F2006B06793","name":"AD/SC7/18 - Ground/Air Lever Spring Heel Block - Modification","slug":"ad-sc7-18-ground-air-lever-spring-heel-block-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114647,"registerId":"commonwealth-F2006B06793-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SC7/18 - Ground/Air Lever Spring Heel Block - Modification","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 SC7 (Skyvan) Series Aeroplanes\n\n \n\nAD/SC7/18 Ground/Air Lever Spring Heel Block - Modification 2/81\n\nApplicability: All models SC7, Series 3, 3A and 3M. Document:  Shorts SB No. 76-58, Revision No. 1.\n\nCompliance: Within 300 hours time in service after 31 March 1981.\n\n \n\nBackground:  An improved method of security the retaining pin in the ground/air lever spring heel block has now been developed by the manufacturer. The bulletin has been classified as mandatory by the UK CAA.\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 instrument prescribes a specific modification for a defined set of aircraft models and specifies the compliance deadline and the manufacturer's service bulletin to be followed. The text presents the requirement plainly and does not indicate any alteration or expansion of scope beyond that specific modification."},"complexity_factors":["Narrow applicability limited to SC7 Series 3, 3A and 3M (Applicability).","Single, specific technical action required (modification of retaining pin in ground/air lever spring heel block) — limited scope of work (Title; Background).","Fixed, short compliance window tied to flight hours after a calendar date: 300 hours after 31 March 1981 (Compliance).","Dependence on manufacturer's service bulletin for procedural and technical detail (Shorts SB No. 76-58, Revision No. 1), which concentrates substantive instructions outside the AD text.","Cross-reference to another regulator's classification (UK CAA) adds an external compliance framing point but no procedural complexity in the AD itself (Background)."],"plain_english_summary":"This Airworthiness Directive mandates a modification to the retaining pin in the ground/air lever spring heel block on Short SC7 (Skyvan) Series 3, 3A and 3M aircraft, carried out per Shorts SB No. 76‑58 Revision 1. Owners/operators must arrange and fund the work within 300 hours TIS after 31 March 1981; the AD enforces a manufacturer‑developed, UK CAA‑classified mandatory improvement."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive issued under Part 39 of the Civil Aviation Regulations 1988. It addresses a specific mechanical defect in a specific aircraft series. There is no indication of scope creep; it remains tightly focused on its original safety purpose."},"complexity_factors":["Single, specific technical requirement affecting only one aircraft type","No defined terms section or complex interpretation provisions","Simple compliance deadline (300 hours time in service from fixed date)","No nested exceptions, conditional logic, or cross-references to other legislation","Document reference is external (manufacturer's service bulletin) but clearly specified","Extremely short — 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 owners and operators of specific Short SC7 Skyvan aircraft to carry out a safety modification.\n\n**What it does:**\n- Orders a fix to the **ground/air lever spring heel block** — a mechanical component in the aircraft's landing gear system that controls whether the plane thinks it's on the ground or in the air (this affects things like braking and steering systems).\n- The fix involves securing a **retaining pin** more reliably to prevent it from coming loose.\n\n**Who it affects:**\n- Owners and operators of **Short SC7 Series 3, 3A and 3M aircraft** — these are twin-turboprop utility planes, often used for skydiving, cargo, or regional transport.\n\n**Why it matters:**\n- A loose retaining pin could cause the ground/air sensing system to fail, potentially leading to dangerous situations during takeoff, landing, or taxiing.\n- The UK aviation regulator (CAA) classified this as mandatory, and Australia is adopting the same requirement.\n\n**What must be done:**\n- Follow the manufacturer's Service Bulletin (Shorts SB No. 76-58, Revision 1).\n- Complete the modification **within 300 flight hours after 31 March 1981**."}},"importantCases":[],"_links":{"self":"/api/acts/ad-sc7-18-ground-air-lever-spring-heel-block-modification","history":"/api/acts/ad-sc7-18-ground-air-lever-spring-heel-block-modification/history","analysis":"/api/acts/ad-sc7-18-ground-air-lever-spring-heel-block-modification/analysis","conflicts":"/api/acts/ad-sc7-18-ground-air-lever-spring-heel-block-modification/conflicts","importantCases":"/api/acts/ad-sc7-18-ground-air-lever-spring-heel-block-modification/important-cases","documents":"/api/acts/ad-sc7-18-ground-air-lever-spring-heel-block-modification/documents"}}