{"id":"F2005L02414","name":"AD/LA-4/23 Amdt 1 - Wing Fitting Carry Through Structure","slug":"ad-la-4-23-amdt-1-wing-fitting-carry-through-structure","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":36916,"registerId":"commonwealth-F2005L02414-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Consolidated Aeronautics, Colonial and L","sectionType":"division","heading":"Consolidated Aeronautics, Colonial and LA-4 Series Aeroplanes","content":"### Consolidated Aeronautics, Colonial and LA-4 Series Aeroplanes\n\n| AD/LA-4/23 Amdt 1 | Wing Fitting Carry Through Structure | 10/2005 |\n| ----------------- | ------------------------------------ | ------- |\n\n| Applicability: | All models.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Perform the modification, inspection and corrosion treatment of the wing carry through structure in accordance with the instructions contained in Aerofab Service Advisory No. A-001 Dated 4 May 1991 or later revision approved by the Type Certificate holder.Note: The previous amendment of this AD required the wings to be removed to perform a corrosion inspection. This amendment does not require wing removal as the required inspection is now performed using a borescope inserted through a small hole in the wing carry through structure.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n| Compliance:    | Initial modification and first inspection:For aircraft inspected in the last 3 years to the original issue of this AD or previously inspected in accordance with an exclusion allowing the inspection to be carried out in accordance with Aerofab Service Advisory No A-001, accomplish the inspection and treatment no later than 3 years since the last inspection.For aircraft recently imported and not inspected previously to the original issue of this AD or inspected in accordance with an exclusion allowing the use of Aerofab Service Advisory No A-001, perform the initial modification and inspection within 3 months from the effective date of this AD.Subsequent repeat inspections:Repeat inspections every 3 years for aircraft subject to predominantly salt water activity*.*Predominantly salt water activity is defined as landings and takeoffs being made in salt water as the primary surface, involving more than weekly landings/takeoffs in salt water (i.e. 4 or more per month) or mooring the aircraft for extended periods of time in salt water for greater than 60 days per year. |\n\n|             | Or, repeat inspections every 6 years for aircraft subject to predominantly fresh water operations*.*Predominantly fresh water operations are operations where salt water is encountered infrequently i.e. less than weekly landings/takeoffs in salt water (i.e. less than 4 times a month) or mooring the aircraft in salt water for less than 60 days per year.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |\n| ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|             | This Amendment becomes effective on 29 September 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |\n| Background: | Reports have been received by the Authority of severe corrosion damage affecting the wing fuselage carry through structures, which if undetected could lead to structural failure.This amendment allows the use of a procedure approved by the manufacturer, which uses a borescope to inspect the centre section for corrosion. The new procedure does not require removal of the wings and hence minimises disturbance of the structure and thus greatly minimises the time taken to do the inspection.There is no change to the compliance time of a minimum inspection period of 3 years. However, in some cases, operators will now have up to 6 years between inspections depending on the type of environment the aircraft is predominantly operated in. The requirements of the AD are changed to reflect the current manufacturer approved method of inspecting the wing centre section for corrosion using a borescope, instead of wing removal and a normal unaided visual inspection.The original issue of this AD became effective on 13 July 1989. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n8 August 2005","sortOrder":0},{"sectionNumber":"AD/LA-4/23 Amdt 1","sectionType":"part","heading":"AD/LA-4/23 Amdt 1","content":"## AD/LA-4/23 Amdt 1","sortOrder":1},{"sectionNumber":"Wing Fitting Carry Through Structure","sectionType":"part","heading":"Wing Fitting Carry Through Structure","content":"## Wing Fitting Carry Through Structure","sortOrder":2},{"sectionNumber":"10/2005","sectionType":"part","heading":"10/2005","content":"## 10/2005","sortOrder":3}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This amendment changes the inspection method (permits borescope inspection through a small hole instead of removing the wings) and adjusts repeat inspection intervals based on operating environment (3 years for salt‑water operations, up to 6 years for predominantly fresh‑water operations). It retains a 3‑year minimum inspection baseline for previously inspected aircraft but adds a 3‑month initial deadline for recently imported, previously uninspected aircraft and defers procedural detail to Aerofab Service Advisory A‑001 or later TC‑holder‑approved revisions."},"complexity_factors":["Multiple overlapping compliance timelines (3 months for recent imports, 3 years baseline, 3‑ or 6‑year repeats) creating scheduling and recordkeeping complexity (Compliance section).","Operational‑environment classification with quantitative thresholds (predominantly salt water defined as ≥4 salt‑water landings/takeoffs per month or >60 days/mooring/year) requires operators to evidence and justify classification.","Allowance for inspections per Aerofab Service Advisory A‑001 or later revisions approved by the Type Certificate holder introduces administrative discretion and potential variance in methods.","Change of inspection technique from full wing removal to borescope inspection reduces labour but requires specific tooling, access‑hole preparation and borescope competency.","Applicability to all models broadens scope of affected operators and maintenance organisations.","Requirement includes both modification and corrosion treatment, so operators must source parts, materials and approved procedures, not merely perform inspections."],"plain_english_summary":"**What it changes:** This airworthiness directive requires all Consolidated Aeronautics, Colonial and LA‑4 series aeroplanes to have the wing carry‑through structure modified, inspected and corrosion‑treated following Aerofab Service Advisory A‑001 (or a later Type Certificate holder‑approved revision). The amendment allows inspection by borescope through a small access hole instead of removing the wings. \n\nIt sets deadline rules: recent imports must be inspected within 3 months, previously inspected aircraft follow a 3‑year baseline, and repeat inspections are every 3 years for predominantly salt‑water operations or every 6 years for predominantly fresh‑water operations to control corrosion risk."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"The amendment remains tightly focused on its original purpose: preventing structural failure due to corrosion in the wing carry through structure of specific amphibious aircraft. While the inspection method has been modernised (borescope vs. wing removal) and inspection intervals made more flexible based on operational environment, these are refinements to the same safety objective rather than scope expansion."},"complexity_factors":["Multiple compliance pathways based on inspection history (recently inspected vs. newly imported)","Dual inspection intervals (3-year vs. 6-year) contingent on operational environment definitions","Two defined operational terms requiring calculation ('predominantly salt water activity' and 'predominantly fresh water operations' with specific thresholds: 4+ landings/month or 60+ days mooring)","Reference to external technical document (Aerofab Service Advisory No. A-001) for actual procedures","Nested conditional logic: compliance dates depend on prior inspection status, which depends on which version of the AD was previously complied with"],"plain_english_summary":"This AD requires owners of Consolidated Aeronautics, Colonial and LA-4 series amphibious aeroplanes to inspect and treat corrosion in the wing carry‑through structure to prevent catastrophic wing failure. The 2005 amendment permits a less invasive borescope inspection instead of removing wings, reducing cost and disruption. Affected aircraft must have an initial inspection within three months if not recently inspected, then recurring checks every 3 years (primarily salt‑water use) or 6 years (primarily fresh‑water use)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-la-4-23-amdt-1-wing-fitting-carry-through-structure","history":"/api/acts/ad-la-4-23-amdt-1-wing-fitting-carry-through-structure/history","analysis":"/api/acts/ad-la-4-23-amdt-1-wing-fitting-carry-through-structure/analysis","conflicts":"/api/acts/ad-la-4-23-amdt-1-wing-fitting-carry-through-structure/conflicts","importantCases":"/api/acts/ad-la-4-23-amdt-1-wing-fitting-carry-through-structure/important-cases","documents":"/api/acts/ad-la-4-23-amdt-1-wing-fitting-carry-through-structure/documents"}}