{"id":"F2006B07596","name":"AD/W620/1 Amdt 1 - Wing Fatigue Life Limitation","slug":"ad-w620-1-amdt-1-wing-fatigue-life-limitation","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":50261,"registerId":"commonwealth-F2006B07596-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/W620/1 Amdt 1 - Wing Fatigue Life Limitation","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \n\nAIRWORTHINESS DIRECTIVE\n\n![](image.001.png)\n\n![](image.001.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/W620/1 and issues the following 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\nWeatherly 620 Series Aeroplanes\n\nAD/W620/1\n\nAmdt 1\n\n  \nWing Fatigue Life Limitation 8/2002\n\nApplicability: All Models.\n\nRequirement: Retire the following items from service before the times shown:\n\n| Item                              | Life Limit                  |\n| --------------------------------- | --------------------------- |\n| Wing Main Spar Lower Cap Assembly | 2500 hours time in service  |\n| Steel Wing Attachment Fittings    | 5000 hours time in service. |\n\nCompliance: This Amendment becomes effective on 8 August 2002.\n\nBackground: As a result of a request for review of this Directive, the fatigue lives of the wing main spar lower cap assembly and steel wing attachment fittings have been increased in line with a fatigue substantiation report provided by the manufacturer.\n\nThe Authority is willing to consider submissions which substantiate that fatigue can safely be controlled by inspection beyond the life limits stipulated by this directive. This will require evidence, from analysis, test or service experience, that any proposed inspection program looks in the right places, in the right way, at the right times. Acceptable standards are CAO 101.22.3.61 or FAR 23.573(b).\n\nThe original issue of this Airworthiness Directive became effective on 18 November 1992.\n\n![Signature of David Alan Villiers Delegate of the Civil Aviation Safety Authority](image.002.jpeg)  \n\nDavid Alan Villiers\n\nDelegate of the Civil Aviation Safety Authority 25 June 2002\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 17 July 2002\n\n  \nPage 1 of 1","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment adjusts the numeric life limits for two wing components (increasing them per a manufacturer fatigue substantiation report) and reiterates that inspection-based extensions may be considered with supporting evidence. It remains within the original scope (managing wing fatigue life for Weatherly 620 series aircraft) rather than expanding the AD’s substantive scope beyond that safety focus."},"complexity_factors":["Short, single-topic directive (wing fatigue life limits) — limited length","Simple applicability: one aircraft family (“All Models”)","Small number of regulated items: two components with numeric life limits","One conditional pathway: inspection-based extension allowed but requires substantiation to specified standards (CAO 101.22.3.61 or FAR 23.573(b))","Cross-reference to external technical standards (requires users to consult those documents)","Administrative element: CASA delegate revokes prior AD and retains discretion to accept alternative programs"],"plain_english_summary":"**What this instrument does (mechanically)**\n\n- It replaces a previous airworthiness directive for Weatherly 620 series aeroplanes and sets mandatory retirement (life) limits for two wing components.  The AD applies to all Weatherly 620 models.\n- Operators must remove the following items from service before they reach the specified accumulated hours in service:\n  - Wing main spar lower cap assembly — retire at 2,500 hours time in service.\n  - Steel wing attachment fittings — retire at 5,000 hours time in service.\n- The amendment took effect on 8 August 2002.\n- The Civil Aviation Safety Authority (CASA) delegate issued the AD under the power in the Civil Aviation Regulations; the delegate also revoked the earlier AD and replaced it with this version.\n\n**Why the change was made (official rationale)**\n\n- The background states the manufacturer provided a fatigue substantiation report supporting increased fatigue lives for these components; the AD reflects the revised allowable hours.\n- CASA also says it will consider operator proposals to control fatigue by inspection beyond the stated life limits, but only if supported by analysis, testing or service experience that shows inspections target the right locations, methods and intervals. Acceptable standards for such evidence are CAO 101.22.3.61 or FAR 23.573(b) (both set out fatigue/inspection substantiation requirements).\n\n**Who this affects and who decides**\n\n- Who is directly affected: owners and operators of Weatherly 620 series aeroplanes, their maintenance organisations, and parts suppliers.\n- Who decides: the CASA delegate sets the mandatory retirement times; CASA can accept alternative inspection-based programs if operators provide the required substantiating evidence.\n\n**Practical effects on behaviour and costs**\n\n- Operators must track time-in-service on the two listed parts and remove/replace them when they hit the life limits. That creates direct costs: replacement parts, labour, and aircraft down-time.\n- Maintenance providers will perform the removals/replacements and, if approved, any alternative inspection regimes. Parts suppliers may see steady demand from mandatory replacements; operators may face availability or lead-time risks for those parts.\n- An operator can propose an inspection regime to extend part life, but must provide analysis/test/service evidence meeting the cited standards. CASA has discretion to accept or reject such proposals, which imposes a documentation and approval burden on the proposer.\n\n**Trade-offs, risks and implementation notes**\n\n- The AD converts a fatigue-risk judgement into a hard operational constraint (specific hours). That reduces uncertainty about when parts must be removed but imposes economic cost on operators.\n- Allowing inspection-based extensions creates a pathway to reduce replacement costs, but only if the operator can produce suitably rigorous evidence; preparing that evidence can itself be costly and time-consuming.\n- Risks include supply or lead-time constraints for replacement components, and the administrative burden on CASA to review inspection substantiations. The AD points to external technical standards (CAO 101.22.3.61 or FAR 23.573(b)), so operators must align proposals to those texts.\n\n**Source-based limitations on conclusions**\n\n- The AD cites a manufacturer fatigue substantiation report as the basis for changing the life limits; the AD itself does not publish the underlying analysis. Any assertion about how conservative or permissive the new limits are would require reviewing that report or service data.\n\n(References within the AD: applicability “All Models”; Requirement table with life limits; Compliance effective date 8 August 2002; Background: manufacturer report and acceptance of inspection-based alternatives subject to CAO/FAR standards.)"},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The legislation maintains its original narrow scope — regulating fatigue life limits for specific structural components on a single aircraft series. The amendment simply adjusts the numerical limits based on updated engineering data, without expanding to cover additional aircraft types, components, or operational scenarios."},"complexity_factors":["Very short document (1 page)","Only 2 defined items with specific life limits","Simple table format for requirements","No nested exceptions or conditional logic — just two hard deadlines","Single applicability clause ('All Models')","Minimal cross-referencing (only mentions CAO 101.22.3.61 and FAR 23.573(b) as optional standards for alternative compliance submissions)","Clear compliance date (8 August 2002)"],"plain_english_summary":"This Airworthiness Directive requires owners/operators and maintenance organisations of Weatherly 620 series aeroplanes to retire two critical wing components at fixed service lives: the wing main spar lower cap after 2,500 flight hours and the steel wing attachment fittings after 5,000 hours. The amendment raises allowable lives from the 1992 rule based on manufacturer analysis but still mandates retirement unless you obtain CASA approval with engineering evidence that inspections will reliably detect fatigue cracks."}},"importantCases":[],"_links":{"self":"/api/acts/ad-w620-1-amdt-1-wing-fatigue-life-limitation","history":"/api/acts/ad-w620-1-amdt-1-wing-fatigue-life-limitation/history","analysis":"/api/acts/ad-w620-1-amdt-1-wing-fatigue-life-limitation/analysis","conflicts":"/api/acts/ad-w620-1-amdt-1-wing-fatigue-life-limitation/conflicts","importantCases":"/api/acts/ad-w620-1-amdt-1-wing-fatigue-life-limitation/important-cases","documents":"/api/acts/ad-w620-1-amdt-1-wing-fatigue-life-limitation/documents"}}