{"id":"F2006B11094","name":"AD/LEARJET 35/16 - Maximum Operating Airspeed (VMO) - Reduction and Terminating Modification","slug":"ad-learjet-35-16-maximum-operating-airspeed-vmo-reduction-and-terminating-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56754,"registerId":"commonwealth-F2006B11094-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LEARJET 35/16 - Maximum Operating Airspeed (VMO) - Reduction and Terminating 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)  Gates Learjet 35 and 36 Series Aeroplanes\n\n \n\n# AD/LEARJET 35/16 Maximum Operating Airspeed\n\n(VMO) - Reduction and Terminating Modification\n\nApplicability: All model 35 series with S/Nos. 35-050 to 35-339 except 35-054 and 35-065.\n\n \n\nAll model 36 series with S/Nos. 36-017 and 36-045.\n\n# 11/80\n\n \n\nRequirement: To prevent the encountering of a possible overload flight condition that could fail the forward engine mount, accomplish the following:\n\n \n\n1. Install airspeed warning placards and modify the mach/overspeed switch circuit to effect a reduced maximum operating airspeed (VMO) of 307 KIAS, from sea level to 31,100 feet altitude.\n\n\n \n\n2.    Replace or re-age both forward engine mounts in accordance with Gates Learjet Corporation Airplane Modification Kit AMK 80-6.\n\n \n\nNote: FAA AD 80-17-11, Amdt. 39-3888 refers.\n\n \n\nCompliance: Para. 1 - Within 75 hours time in service after 8 October 1980. Reduction in VMO to remain until modified in accordance with Para. 2 requirement.\n\n \n\nPara. 2 - Within 600 hours time in service after 8 October 1980.\n\n \n\nBackground:  Exceeding the maximum operating airspeed is suspected as a causal factor in recent overseas accidents involving the subject model aeroplanes.\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_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"No. The directive reduces VMO for the specified serial numbers and mandates a terminating structural/aging modification to address potential forward engine mount overloads. That implementation aligns with the directive's stated purpose (Requirement; Background; Compliance) and does not broaden or narrow the set of affected aircraft beyond the written applicability."},"complexity_factors":["Technical avionics change: modify mach/overspeed switch circuit and install placards (Requirement, Para. 1).","Structural work: replace or re‑age both forward engine mounts per AMK 80‑6 (Requirement, Para. 2).","Fixed compliance windows: 75 hours TIS for VMO reduction action and 600 hours TIS for terminating modification (Compliance, Para. 1–2).","Narrow airframe scope limited to specific serial numbers (Applicability).","Dependence on manufacturer modification kit and reference to FAA AD (Note; FAA AD 80‑17‑11).","Operational constraint: reduced VMO remains in force until the terminating modification is embodied (Compliance, Para. 1).","Safety‑critical nature increases need for correct installation, airworthiness records and potential downtime."],"plain_english_summary":"Mechanically: lowers the maximum operating airspeed (VMO) to 307 KIAS by installing airspeed‑warning placards and modifying the mach/overspeed switch, and requires replacing or re‑aging both forward engine mounts per Gates Learjet AMK 80‑6. Affects Learjet 35 and 36 aircraft with the listed serial numbers. The stated purpose is to prevent overload failures of the forward engine mount after overspeed events; operators must comply within specified flight‑hour windows, incurring maintenance and parts costs."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive with a clear original purpose (addressing engine mount failure risk) and no evidence of scope creep. The document represents its complete original intent."},"complexity_factors":["Single, clearly defined applicability (specific serial numbers)","Two straightforward compliance requirements with simple timelines","Minimal defined terms (only VMO and KIAS, both standard aviation abbreviations)","No cross-references to other legislation beyond a single FAA reference note","No conditional logic or nested exceptions","Short document (approximately 250 words)"],"plain_english_summary":"This AD mandates immediate speed limits and a permanent structural repair for certain Gates Learjet 35/36 aircraft (specific serials listed). Operators must reduce VMO to 307 KIAS up to 31,100 ft via placards and overspeed-warning changes, and ultimately replace or re-age both forward engine mounts using AMK 80-6.\n\nThe measures respond to overseas accidents where overspeed likely caused forward engine‑mount failure and possible engine loss. The speed restriction is temporary until the mount replacement/re‑aging is completed within the specified compliance hours."}},"importantCases":[],"_links":{"self":"/api/acts/ad-learjet-35-16-maximum-operating-airspeed-vmo-reduction-and-terminating-modification","history":"/api/acts/ad-learjet-35-16-maximum-operating-airspeed-vmo-reduction-and-terminating-modification/history","analysis":"/api/acts/ad-learjet-35-16-maximum-operating-airspeed-vmo-reduction-and-terminating-modification/analysis","conflicts":"/api/acts/ad-learjet-35-16-maximum-operating-airspeed-vmo-reduction-and-terminating-modification/conflicts","importantCases":"/api/acts/ad-learjet-35-16-maximum-operating-airspeed-vmo-reduction-and-terminating-modification/important-cases","documents":"/api/acts/ad-learjet-35-16-maximum-operating-airspeed-vmo-reduction-and-terminating-modification/documents"}}