{"id":"F2007L00334","name":"AD/DHC-2/24 Amdt 4 - Wing Strut Assembly Lower Attachment Fittings","slug":"ad-dhc-2-24-amdt-4-wing-strut-assembly-lower-attachment-fittings","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":63327,"registerId":"commonwealth-F2007L00334-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"DHC-2 (Beaver) Series Aeroplanes","sectionType":"division","heading":"DHC-2 (Beaver) Series Aeroplanes","content":"### DHC-2 (Beaver) Series Aeroplanes\n\n| AD/DHC-2/24 Amdt 4 | Wing Strut Assembly LowerAttachment Fittings | 3/2007 |\n| ------------------ | -------------------------------------------- | ------ |\n\n| Applicability: | All Models DHC-2 aircraft fitted with wing lift strut part numbers C2W1103, C2W1103A, C2W1104, or C2W1104A.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Part A - Inspection using fluorescent penetrant method.Action in accordance with the Accomplishment Instructions of Viking Air Ltd (formerly Bombardier/de Havilland Canada) Service Bulletin No. 2/41 Revision C, dated 23 June 2006, or a later Transport Canada approved revision. The fluorescent penetrant inspection of the lower clevis fitting shall be carried out by a person holding a valid appropriate Non-Destructive Testing Authority.Part B - Inspection using Eddy Current method.Action in accordance with the Accomplishment Instructions of Viking Air Ltd Service Bulletin No. 2/55, dated 23 June 2006, or a later Transport Canada approved revision.Note: Transport Canada AD CF-1985-08R4 refers.                                                     |\n| Compliance:    | Part A - Inspection using fluorescent penetrant method.For aircraft operating in a salt water environment:I. For aircraft which have complied with Amendment 3 of this Directive, within one calendar year since the previous inspection, and thereafter at intervals not to exceed one calendar year; andII. For aircraft which have not complied with Amendment 3 of this Directive, within 100 hours time in service or one calendar year after 15 March 2007, whichever occurs first, and thereafter at intervals not to exceed one calendar year.For all other aircraft:I. For aircraft which have complied with Amendment 3 of this Directive, within two calendar years since the previous inspection, and thereafter at intervals not to exceed two calendar years; and |\n\n|             | II. For aircraft which have not complied with Amendment 3 of this Directive, within 100 hours time in service or one calendar year after 15 March 2007, whichever occurs first, and thereafter at intervals not to exceed two calendar years.Part B - Inspection using Eddy Current method.For aircraft operating in a salt water environment:I. For aircraft which have complied with Amendment 3 of this Directive, within one calendar year since the previous inspection, thereafter at intervals not to exceed two calendar years; andII. For aircraft which have not complied with Amendment 3 of this Directive, within 100 flight hours or one calendar year after 15 March 2007, whichever occurs first, and thereafter at intervals not to exceed two calendar years.For all other aircraft:I. For aircraft which have complied with Amendment 3 of this Directive, within two calendar years since the previous inspection, and thereafter at intervals not to exceed five calendar years; andII. For aircraft which have not complied with Amendment 3 of this Directive, within 100 flight hours or one calendar year after 15 March 2007, whichever occurs first, and thereafter at intervals not to exceed five calendar years.If cracks are detected during any Part A or Part B inspection required by this Directive, before further flight, remove the affected strut from service. |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n|             | This Amendment becomes effective on 15 March 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |\n| Background: | A report was received of stress corrosion cracking occurring in the wing lift strut lower clevis fitting. This Directive requires certain actions in order to preclude failure of the wing lift strut.Amendment 1 expanded the part number applicability and removed the serial number range and date of manufacture provisions.Amendment 2 replaced the dye penetrant inspection with the fluorescent penetrant inspection.Amendment 3 allowed a longer inspection interval for aircraft which are not operated in a salt water environment.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |\n\n|     | Amendment 4 is issued in response to a revision of the related Transport Canada AD, which allows operators the option of continuing with the current inspection intervals or incorporating the improved alternate inspection method, to permit an increase in inspection intervals. |\n| --- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n2 February 2007","sortOrder":0},{"sectionNumber":"AD/DHC-2/24 Amdt 4","sectionType":"part","heading":"AD/DHC-2/24 Amdt 4","content":"## AD/DHC-2/24 Amdt 4","sortOrder":1},{"sectionNumber":"Wing Strut Assembly LowerAttachment Fitt","sectionType":"part","heading":"Wing Strut Assembly LowerAttachment Fittings","content":"## Wing Strut Assembly Lower  \nAttachment Fittings","sortOrder":2},{"sectionNumber":"3/2007","sectionType":"part","heading":"3/2007","content":"## 3/2007","sortOrder":3}],"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":6,"scope_assessment":{"changed":true,"description":"Yes. The Directive's scope and procedures have been changed across amendments. Amendment 1 expanded part-number applicability and removed serial-number/date-of-manufacture limitations. Amendment 2 replaced dye penetrant with fluorescent penetrant inspection. Amendment 3 permitted longer inspection intervals for aircraft not operated in a salt-water environment. Amendment 4 (this amendment) allows operators the option to continue with existing inspection intervals or adopt an improved alternate inspection method that permits increases in inspection intervals (Background; Amendment 1; Amendment 2; Amendment 3; Amendment 4)."},"complexity_factors":["Two different inspection methods (Part A: fluorescent penetrant; Part B: eddy current) with distinct procedural and personnel requirements (Requirement: Part A; Requirement: Part B).","Multiple inspection-interval schedules that vary by method, by whether the aircraft operates in a salt-water environment, and by whether the aircraft complied with Amendment 3 (Compliance).","Dependence on external technical documents and approvals: inspections must follow Viking Air Ltd Service Bulletins or later Transport Canada–approved revisions (Requirement).","Requirement that fluorescent penetrant inspection be performed by a person with a valid Non‑Destructive Testing Authority increases personnel-certification burden (Requirement: Part A).","Immediate operational consequence (remove strut from service before further flight) if cracks are found, creating potential downtime and repair costs (Compliance).","Multiple historical amendments changing applicability and inspection approach (Amendment 1, Amendment 2, Amendment 3, Amendment 4) increase interpretive complexity for which rules currently apply to a given aircraft (Background; Amendment 4)."],"plain_english_summary":"The instrument requires regular non‑destructive inspections of wing lift‑strut lower clevis fittings on DHC‑2 (Beaver) aircraft with specified strut part numbers, mandating fluorescent‑penetrant and eddy‑current checks per Viking service bulletins. Fluorescent tests must be done by qualified NDT personnel and any cracked strut removed before flight. Inspection intervals vary by method, salt‑water exposure and prior amendment compliance; Amendment 4 lets operators opt for an alternate method to extend intervals."},"kimi_summary":{"content_quality":"ok","complexity_score":6,"scope_assessment":{"changed":true,"description":"The original directive (dating back to 1985) has expanded significantly through four amendments. Amendment 1 broadened applicability beyond serial number ranges; Amendment 2 changed inspection technology; Amendment 3 introduced environmental differentiators (salt water vs other); Amendment 4 adds optional improved inspection methods with extended intervals. What began as a simple crack inspection requirement has evolved into a complex multi-pathway compliance framework with four amendments worth of accumulated exceptions and alternatives."},"complexity_factors":["Multiple nested conditional logic: compliance deadlines vary based on (a) which amendment was previously complied with, (b) operating environment (salt water vs other), and (c) inspection method chosen","Cross-references to external documents: requires compliance with specific Viking Air Ltd Service Bulletins (2/41 Rev C and 2/55) and Transport Canada AD CF-1985-08R4","Dual inspection regimes (Part A and Part B) with different compliance intervals and methods","Time-based calculations using multiple metrics: 'hours time in service', 'flight hours', 'calendar years', and specific calendar date (15 March 2007)","Four distinct compliance pathways for each inspection part based on environmental and historical compliance variables","Technical terminology requiring specialist knowledge: 'fluorescent penetrant', 'Eddy Current', 'Non-Destructive Testing Authority', 'clevis fitting'"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It applies to owners and operators of **DHC-2 Beaver aircraft**, a type of Canadian-built bush plane commonly used in Australia.\n\n**What it does:**\nThe directive requires regular safety inspections of the **wing strut lower attachment fittings** — the metal parts that connect the wing support struts to the aircraft body. These fittings have been found to develop **stress corrosion cracking**, which could cause the wing strut to fail in flight.\n\n**What owners must do:**\n- **Part A:** Inspect the fittings using a **fluorescent penetrant** method (a special dye that reveals cracks under UV light). This must be done by someone with proper non-destructive testing qualifications.\n- **Part B:** Inspect using an **Eddy Current** method (an electromagnetic technique that detects cracks beneath the surface).\n\n**How often:**\n- **Salt water environment:** Every 1–2 years depending on which inspection method is used and whether previous amendments were followed.\n- **Other environments:** Every 2–5 years depending on the same factors.\n- **If cracks are found:** The strut must be removed from service immediately before the aircraft flies again.\n\n**Why it matters:**\nWing strut failure could lead to catastrophic structural collapse in flight. This amendment (the 4th update to the original 1985 directive) gives operators more flexibility by allowing longer inspection intervals if they use improved testing methods."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-2-24-amdt-4-wing-strut-assembly-lower-attachment-fittings","history":"/api/acts/ad-dhc-2-24-amdt-4-wing-strut-assembly-lower-attachment-fittings/history","analysis":"/api/acts/ad-dhc-2-24-amdt-4-wing-strut-assembly-lower-attachment-fittings/analysis","conflicts":"/api/acts/ad-dhc-2-24-amdt-4-wing-strut-assembly-lower-attachment-fittings/conflicts","importantCases":"/api/acts/ad-dhc-2-24-amdt-4-wing-strut-assembly-lower-attachment-fittings/important-cases","documents":"/api/acts/ad-dhc-2-24-amdt-4-wing-strut-assembly-lower-attachment-fittings/documents"}}