{"id":"F2006B11143","name":"AD/LEARJET/26 - Flight Manual - Change To Metric Units","slug":"ad-learjet-26-flight-manual-change-to-metric-units","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56829,"registerId":"commonwealth-F2006B11143-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LEARJET/26 - Flight Manual - Change To Metric Units","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)  \nGates Learjet 24 & 25 Series Aeroplanes\n\nAD/LEARJET/26 Flight Manual \\- Change To Metric Units 9/81\n\nApplicability: All Gates Learjet 24D and 25C series aeroplanes.\n\nRequirement: The D.o.T. approved flight manual shall be amended to specify quantities in the following units;\n\n    (a) weight in kilograms,\n\n    (b) distances in metres,\n\n    (c) centre of gravity limits and moment arms in millimetres,\n\n    (d) fuel and oil quantities in litres, and\n\n    (e) pressures in kilopascals.\n\nWhere the installed aircraft instrumentation is calibrated in units other than the above the flight manual shall specify both systems of units.\n\nCompliance: By 1 January 1984.\n\nBackground: It is required that all Australian aircraft be provided with airworthiness limitations and operational data in the declared metric units.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This directive maintains its original narrow scope. It was always intended as a targeted technical amendment for specific aircraft models to align flight documentation with Australia's metric system, and it does exactly that without expansion into broader operational or safety matters."},"complexity_factors":["Very short document (approximately 150 words)","Only 5 specific unit conversion requirements listed","Single conditional exception (dual-unit requirement when instrumentation differs)","No defined terms section","No cross-references to other legislation beyond basic citation","Clear, unambiguous compliance date","Straightforward applicability statement (two specific aircraft models)"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety instruction) issued by Australia's Civil Aviation Safety Authority for specific Learjet aircraft models.\n\n**What it does:**\nIt requires owners and operators of **Gates Learjet 24D and 25C series aeroplanes** to update their aircraft flight manuals to use **metric units** instead of imperial measurements.\n\n**Specific changes required:**\n- **Weight** must be shown in **kilograms** (not pounds)\n- **Distances** must be shown in **metres** (not feet)\n- **Centre of gravity limits and moment arms** must be shown in **millimetres** (not inches)\n- **Fuel and oil quantities** must be shown in **litres** (not gallons)\n- **Pressures** must be shown in **kilopascals** (not psi or other units)\n\n**Important exception:** If the aircraft's actual instruments (gauges, dials) still use the old imperial units, the flight manual must show **both** systems side-by-side.\n\n**Who it affects:**\nAnyone operating these specific Learjet models in Australia.\n\n**Why it matters:**\nThis ensures Australian pilots and maintenance crews work with consistent, standardised measurements that match Australia's metric system—reducing confusion and potential safety errors during flight operations, refuelling, weight calculations, and maintenance.\n\n**Deadline:**\nAll changes had to be completed by **1 January 1984**."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The AD implements the Background objective (that Australian aircraft be provided with airworthiness limitations and operational data in declared metric units) for the specified Learjet models. It does not expand or narrow that stated objective in the text provided; instead it applies the metric‑unit requirement to Gates Learjet 24D and 25C aircraft by mandating flight manual amendments and a compliance date. (Background, Applicability, Requirement, Compliance)"},"complexity_factors":["Narrow technical scope: applies to a specific aircraft group (Gates Learjet 24D and 25C). (Applicability)","Prescriptive unit list requiring specific metric units for different quantities. (Requirement)","Dual‑unit provision where instruments remain in non‑metric units increases documentation content and checking. (Requirement)","Regulatory approval requirement: changes must appear in the D.o.T.‑approved flight manual, introducing administrative steps. (Requirement)","Fixed compliance deadline requiring timely action by operators. (Compliance)","Conversion and transcription risk when changing numerical values and limits; procedural safeguards needed. (Requirement)"],"plain_english_summary":"This directive requires the D.o.T.‑approved flight manual for Gates Learjet 24D and 25C aircraft to be amended to show key quantities in metric units (kg, m, mm, L, kPa), with dual units shown where instruments use other measures. Owners/operators (or their document holders) must pay for and obtain the approved manual amendment by 1 January 1984. The change enforces national metric uniformity, imposing administrative and conversion costs on a small group of operators."}},"importantCases":[],"_links":{"self":"/api/acts/ad-learjet-26-flight-manual-change-to-metric-units","history":"/api/acts/ad-learjet-26-flight-manual-change-to-metric-units/history","analysis":"/api/acts/ad-learjet-26-flight-manual-change-to-metric-units/analysis","conflicts":"/api/acts/ad-learjet-26-flight-manual-change-to-metric-units/conflicts","importantCases":"/api/acts/ad-learjet-26-flight-manual-change-to-metric-units/important-cases","documents":"/api/acts/ad-learjet-26-flight-manual-change-to-metric-units/documents"}}