{"id":"F2006B11076","name":"AD/LA-4/27 - Wing Spar Doublers and Spar Cap Angles","slug":"ad-la-4-27-wing-spar-doublers-and-spar-cap-angles","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56715,"registerId":"commonwealth-F2006B11076-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)\n\nConsolidated Aeronautics, Colonial and LA-4 Series Aeroplanes","sortOrder":0},{"sectionNumber":"AD/LA-4/27 Wing Spar Doublers and Spar C","sectionType":"part","heading":"AD/LA-4/27 Wing Spar Doublers and Spar Cap Angles 13/2002","content":"# AD/LA-4/27 Wing Spar Doublers and Spar Cap Angles 13/2002\n\nDM\n\nApplicability: Affected aircraft with wing spar part numbers incorporated, as specified below:\n\n| Model          | Serial Numbers                                                 |\n| -------------- | -------------------------------------------------------------- |\n| Model LA-4     | Serial numbers 246 through 421, 423 through 429, 445, and 446. |\n| Model LA-4A    | Serial numbers 244 and 245.                                    |\n| Model LA-4P    | Serial number 121.                                             |\n| Model LA-4-200 | Serial numbers 422, 430 through 444, 446 and subsequent.       |\n| Model 250      | Serial numbers 1 through 232.                                  |\n\n| Wing Spar Parts       | Part Numbers                             |\n| --------------------- | ---------------------------------------- |\n| Upper Spar Cap Angles | 2-1610-015 and 2-1610-016                |\n| Lower Spar Cap Angles | 2-1610-075 and 2-1610-076                |\n| Upper Spar Doublers   | 2-1610-061 and 2-1610-081 and 2-1610-065 |\n| Lower Spar Doublers   | 2-1610-063 and 2-1610-083                |\n\nRequirement: 1. Inspect the wing spar doublers and spar cap angles for cracks from the root end to the outboard of the wing spar attachment fittings, as follows:\n\n    From inside the wheel well, clean the upper and lower wing spar doublers and adjoining structure to the paint. Use a detergent or mineral-based solvent.\n    Use a strong light source and a 3x magnifying glass to inspect the exposed areas of the upper and lower spar doublers and adjoining structure for cracks. Use a mirror to inspect the exposed edge of the spar cap angle behind the doubler.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"There is no indication in the provided text that the AD has expanded beyond its original safety-focused purpose. The directive narrowly targets inspection of specific wing spar parts on identified serial-numbered aircraft to correct an unsafe condition (cracking). The measures described are consistent with a standard airworthiness directive: identify affected fleet, list affected part numbers, and mandate inspection procedure. The supplied excerpt does not show any added regulatory powers, broader obligations, or scope creep beyond detecting and correcting structural cracks."},"complexity_factors":["Short, single-subject AD focused on one unsafe condition (wing spar doublers and spar cap angles).","Applicability specified by model plus multiple serial-number ranges (5 models with several ranges).","List of 7 specific part numbers to check (upper/lower cap angles and doublers).","Single, straightforward inspection requirement with three discrete procedural steps (clean, inspect with light/magnifier, mirror for hidden edge).","Cross-reference to regulatory authority (subregulation 39.1(1) of CAR 1998) but minimal legal cross-referencing within the AD text.","Missing compliance timing in the supplied excerpt increases implementation ambiguity (raises complexity in practice though not in drafting)."],"plain_english_summary":"**What this directive does (mechanically)\n\n- This is an Airworthiness Directive (AD) that requires owners/operators of certain Consolidated Aeronautics Colonial and LA-4 series aeroplanes to inspect specific wing spar components for cracking. (An AD is a legally enforceable instruction issued by the aviation safety regulator requiring corrective action to fix an identified unsafe condition.)\n\n- The AD identifies which aeroplane models and serial-number ranges are affected (see \"Applicability\"). It also lists the specific wing spar part numbers to check (upper/lower spar cap angles and upper/lower spar doublers).\n\n- The required action (\"Requirement\") is a visual inspection procedure: clean the inside of the wheel well area to bare paint using detergent or mineral-based solvent; use a strong light, a 3× magnifying glass and a mirror to inspect the exposed areas of the upper and lower spar doublers and the exposed edge of the spar cap angle for cracks, from the root end outboard of the wing spar attachment fittings.\n\nWho is affected\n\n- Aircraft owners/operators and their maintenance organisations for the listed models and serial numbers (Model LA-4, LA-4A, LA-4P, LA-4-200, and Model 250) that have the specified wing spar part numbers installed.\n\n- Maintenance personnel who will carry out the inspection and any necessary repairs.\n\nWhy it matters (stated purpose and practical implications)\n\n- The AD is issued to correct an unsafe condition: cracks in wing spar doublers and spar cap angles. Cracks in those structural parts can progress and affect the integrity of the wing attachment area.\n\n- Practically, the AD forces inspection of those parts so that cracks can be detected and dealt with before they grow. That means owners/operators will incur inspection labour time and potentially repair or replacement costs if cracks are found. Aircraft downtime while inspections or repairs are done is also likely.\n\nMechanics, compliance and implementation risks\n\n- The directive specifies exactly which parts and serial-numbered aircraft are in scope (Applicability table) and gives a step-by-step inspection method (Requirement 1). The inspection is a visual one using basic tools (cleaning solvent, strong light, 3× magnifier, mirror).\n\n- The AD text refers to compliance timing being set out in a \"compliance\" section, but the supplied excerpt does not include a specific due date or inspection interval. That missing timing information is an implementation risk: operators need the compliance timeframe to plan inspections and to know when action must be completed.\n\nCosts, incentives and trade-offs (practical assessment)\n\n- Who pays: Owners/operators pay for the inspection, any follow-up non-routine work (repairs/part replacement), and downtime costs.\n\n- Who decides: The CASA delegate (the regulator) issues the AD; maintenance organisations and aircraft owners decide how and when to schedule the inspections and which approved repair/overhaul organisation will perform required corrective work.\n\n- Behavioural change: Operators must add this inspection to maintenance activity for affected aircraft, and if cracks are found, they must repair or replace the affected parts per approved instructions before returning the aircraft to service.\n\n- Market effects: The AD increases near-term demand for inspection and structural repair services for the affected fleet. It does not alter ownership, operational rules, or market entry conditions for maintenance providers beyond the usual certification requirements. Independent maintenance shops that are qualified to perform the inspection and structural repairs can compete to do the work.\n\n- Compliance burden: The inspection is technically simple (visual, magnifier, mirror) but may require access into confined spaces (wheel well) and removal of contaminants/paint. Repair work for structural cracks may be more complex and costly.\n\nConcentrated benefits and diffuse costs\n\n- Benefits (concentrated): Operators of affected aircraft gain reduced risk of in-service structural failure if cracks are found and corrected.\n\n- Costs (diffuse across owners): All affected owners/operators bear inspection and potential repair costs, and aircraft downtime.\n\nOther practical notes\n\n- The AD lists multiple part numbers and serial-number ranges; operators should cross-check their aircraft and installed parts to be certain they are within scope (Applicability; Wing Spar Parts table).\n\n- The AD gives an explicit inspection method (clean to paint, use specific light/magnification and mirror) which reduces ambiguity about how to inspect, but where the compliance timing is absent in the excerpt, operators should obtain the full AD text to confirm deadlines and any required repeat intervals.\n\nKey citations in the text: Applicability table (models, serial numbers), Wing Spar Parts table (part numbers to inspect), Requirement 1 (cleaning and inspection steps)."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with a focused, narrow scope. It addresses a specific unsafe condition in specific aircraft models and does not appear to have expanded beyond its original safety purpose. The scope is precisely limited to wing spar inspections for the identified Lake aircraft models."},"complexity_factors":["Short, single-purpose document focused on one specific inspection task","Clear applicability table with specific serial numbers and part numbers (no ambiguity)","Straightforward procedural requirements with minimal conditional logic","No cross-references to other legislation or complex defined terms","Simple compliance structure: one inspection method described in plain language","Limited to specific aircraft models and serial number ranges (narrow scope)"],"plain_english_summary":"This mandatory CASA Airworthiness Directive orders owners/operators of about 200+ specific Lake amphibious aircraft (LA-4 series and Model 250) to inspect the wing spar doublers and spar cap angles for cracks. The required work: clean the spar area, perform a close visual inspection with strong light, 3× magnifier and mirror to check hidden edges.\n\nCracks in these spar components risk structural failure; compliance is legally required before flight to ensure continued airworthiness."}},"importantCases":[],"_links":{"self":"/api/acts/ad-la-4-27-wing-spar-doublers-and-spar-cap-angles","history":"/api/acts/ad-la-4-27-wing-spar-doublers-and-spar-cap-angles/history","analysis":"/api/acts/ad-la-4-27-wing-spar-doublers-and-spar-cap-angles/analysis","conflicts":"/api/acts/ad-la-4-27-wing-spar-doublers-and-spar-cap-angles/conflicts","importantCases":"/api/acts/ad-la-4-27-wing-spar-doublers-and-spar-cap-angles/important-cases","documents":"/api/acts/ad-la-4-27-wing-spar-doublers-and-spar-cap-angles/documents"}}