{"id":"F2006B11130","name":"AD/LEARJET/14 Amdt 1 - Upper Cabin Door Locking Mechanism -Inspection And Modification","slug":"ad-learjet-14-amdt-1-upper-cabin-door-locking-mechanism-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56809,"registerId":"commonwealth-F2006B11130-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/LEARJET/14 Amdt 1 - Upper Cabin Door Locking Mechanism -Inspection And 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 24 & 25 Series Aeroplanes\n\n \n\nAD/LEARJET/14\n\nAmdt 1\n\n\nUpper Cabin Door Locking Mechanism - Inspection And Modification\n\n\n2/80\n\n \n\nApplicability: All models 23, 24 and 25 with S/Nos. 23-003 to 23-099, 24-100 to 24-356 and 25-003 to 25-238, with 36 inch cabin door.\n\n \n\nDocument: Gates Learjet SB 23/24/25-280A.\n\n \n\nCompliance: Within 100 hours time in service after achieving 3000 hours time in service and thereafter as per requirement document or until Gates Learjet Modification Kit No. AMK 78-2 is fitted.\n\n \n\nBackground: Failure of the door locking mechanism during door closing can result in a hidden door unsafe condition.\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":true,"description":"The instrument is titled as an amendment (Amdt 1) to AD/LEARJET/14, indicating the text modifies a prior directive. The supplied document does not include the original version, so the exact nature and extent of the change from the prior text cannot be determined from this document alone."},"complexity_factors":["Technical specificity limited to particular models and serial number ranges (Applicability).","Conditional timing trigger based on reaching 3,000 hours time-in-service and a 100-hours follow-up window (Compliance).","Legal requirement cross-references an external manufacturer service bulletin for procedural detail (Document), increasing practical complexity for implementers.","Presence of an explicit terminating action (fitting Modification Kit AMK 78-2) that changes ongoing obligations (Compliance).","Relatively small number of provisions and straightforward regulatory mechanism (inspection, repair, or modification), keeping statutory complexity low."],"plain_english_summary":"What this instrument does (mechanics):\n\n- Requires operators of certain Gates Learjet 23, 24 and 25 series aeroplanes to inspect the upper cabin door locking mechanism, and to modify it where required by the manufacturer’s service document. The inspection and any corrective action must follow the Gates Learjet Service Bulletin referenced (Gates Learjet SB 23/24/25-280A) (Document).\n- Sets when inspections must be done: within 100 hours time-in-service after the aeroplane reaches 3,000 hours time-in-service, and then thereafter in accordance with the referenced requirement document. The recurring inspections stop being required once Gates Learjet Modification Kit No. AMK 78-2 is fitted to the aeroplane (Compliance).\n\nWho it affects:\n\n- Owners and operators of Gates Learjet Models 23, 24 and 25 that have the specified serial number ranges and the 36-inch cabin door (Applicability).\n- Maintenance organisations and engineers who must perform the inspections and modifications called for in the Gates Learjet service bulletin (Document).\n\nWhy it matters (stated safety risk and response):\n\n- The directive is issued because failure of the door locking mechanism during door closing can result in a hidden unsafe condition for the door; the inspection/modification requirement is intended to detect and correct that condition before it leads to a safety incident (Background).\n\nWho pays, who decides, and what behaviour changes:\n\n- Operators/owners pay for the inspections, any resulting repairs or modifications, and for buying and fitting Gates Learjet Modification Kit No. AMK 78-2 if they choose that route (Compliance; Document).\n- The Civil Aviation Safety Authority issues and enforces the directive; Gates Learjet’s service bulletin supplies the technical instructions that maintenance personnel must follow (Document).\n- Operators must track aircraft hours to know when 3,000 hours TIS is reached, schedule and perform the inspection within the next 100 hours TIS, repeat inspections as directed by the requirement document, and/or fit the modification kit to remove the recurring inspection requirement (Applicability; Compliance; Document).\n\nCosts, incentives and trade-offs (mechanisms, not judgments):\n\n- Direct costs: labour and parts for inspections and any corrective work; cost of modification kit AMK 78-2 and labour to fit it (Compliance; Document).\n- Incentive structure: fitting the modification kit removes the need for recurring inspections, so operators face a trade-off between repeated inspection costs and a one-time cost to fit the kit (Compliance).\n- Compliance burden: operators must monitor time-in-service, obtain and follow the Gates Learjet service bulletin for the detailed inspection/modification procedures, and arrange maintenance within the prescribed window (Applicability; Compliance; Document). The AD references an external technical document for the procedural detail, meaning the AD sets the legal requirement but the SB sets the how-to.\n\nImplementation risk and administrative discretion:\n\n- The AD does not itself describe the inspection steps or acceptance criteria; those are in the Gates Learjet service bulletin. That creates dependence on the manufacturer document for correct implementation (Document).\n- The AD sets timing and the terminating action (fitting AMK 78-2) but does not specify enforcement or penalty mechanisms in this text; enforcement would follow the regulator’s usual processes (Compliance).\n\nPractical effects on private choice and operations:\n\n- Operators must choose between recurrent inspections and fitting the modification kit (Compliance). This choice affects maintenance scheduling, aircraft downtime, and cash outlays for parts and labour (Applicability; Document; Compliance).\n\nSource references: applicability, service document, compliance timing and terminating action, and the stated safety background are taken directly from the document’s Applicability, Document, Compliance and Background sections."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is Amendment 1 to an existing Airworthiness Directive, but the scope remains tightly focused on the original safety issue: the upper cabin door locking mechanism on specific Learjet models. The amendment does not appear to expand applicability beyond the originally affected aircraft population or introduce new unrelated requirements."},"complexity_factors":["Single, discrete safety issue (door locking mechanism)","Clear applicability criteria (specific models, serial numbers, door size)","Simple compliance structure: inspect at defined interval OR install modification kit","Only one referenced technical document (service bulletin)","No nested exceptions, conditional logic, or cross-references to other legislation","Total length: approximately 200 words","No defined terms section — common aviation terminology only"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it like a compulsory recall notice, but for aircraft instead of cars.\n\n**What it does:** It requires owners and operators of specific Gates Learjet aircraft (models 23, 24, and 25 with certain serial numbers and the 36-inch cabin door) to **inspect and modify the upper cabin door locking mechanism**.\n\n**Why it matters:** The door locking mechanism can fail during closing, creating a **\"hidden unsafe condition\"** — meaning the door might appear secure when it actually isn't. This could lead to the door opening unexpectedly in flight, with potentially catastrophic consequences.\n\n**Who must comply:** Anyone operating the affected Learjet models must:\n- **Inspect** the door locking mechanism within 100 flight hours after the aircraft reaches 3,000 total flight hours\n- **Repeat inspections** as specified in the referenced service bulletin (Gates Learjet SB 23/24/25-280A), **OR**\n- **Permanently fix** the problem by installing Gates Learjet Modification Kit No. AMK 78-2 (which ends the inspection requirement)\n\n**The bottom line:** This is a **flight safety issue**. Non-compliance means the aircraft cannot legally fly in Australian airspace."}},"importantCases":[],"_links":{"self":"/api/acts/ad-learjet-14-amdt-1-upper-cabin-door-locking-mechanism-inspection-and-modification","history":"/api/acts/ad-learjet-14-amdt-1-upper-cabin-door-locking-mechanism-inspection-and-modification/history","analysis":"/api/acts/ad-learjet-14-amdt-1-upper-cabin-door-locking-mechanism-inspection-and-modification/analysis","conflicts":"/api/acts/ad-learjet-14-amdt-1-upper-cabin-door-locking-mechanism-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-learjet-14-amdt-1-upper-cabin-door-locking-mechanism-inspection-and-modification/important-cases","documents":"/api/acts/ad-learjet-14-amdt-1-upper-cabin-door-locking-mechanism-inspection-and-modification/documents"}}