{"id":"F2007L04733","name":"AD/CRESCO/12 - Fin Leading Edge - Inspection","slug":"ad-cresco-12-fin-leading-edge-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":71216,"registerId":"commonwealth-F2007L04733-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Pacific Aerospace Corporation Cresco Ser","sectionType":"division","heading":"Pacific Aerospace Corporation Cresco Series Aeroplanes","content":"### Pacific Aerospace Corporation Cresco Series Aeroplanes\n\n| AD/CRESCO/12 | Fin Leading Edge - Inspection | 2/2008 DM |\n| ------------ | ----------------------------- | --------- |\n\n| Applicability: | Cresco 08-600 series aircraft, all serial numbers.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Remove the dorsal fin extension and carry out a detailed visual inspection of the leading edge skin in accordance with Pacific Aerospace Ltd Service Bulletin PACSB/CR/043. Repair any defects before further flight. Report any or nil damage to CASA through the Service Difficulty Reporting System.2. Inspect the entire exterior skin of the fin from the leading edge to the rear spar for defects such as cracking, corrosion, working rivets or previous repair doublers. Repair any damage and indicate the position of defects, including previous repairs, on the diagram attached at Appendix A.Note: New Zealand Airworthiness Directive (AD) DCA/CRESCO/13 refers. |\n| Compliance:    | 1. Within 5 hours TIS, and thereafter at intervals not to exceed 300 hours TIS.2. Before 5 January 2008                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |\n|                | This Airworthiness Directive becomes effective on 14 December 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |\n| Background:    | Three occurrence of serious cracking in the leading edge skin underneath the dorsal fin extension have been reported. There have also been reports of chafing and corrosion.Cracking of the leading edge skin can lead to failure of the vertical fin and loss of control of the aircraft.                                                                                                                                                                                                                                                                                                                                                                                          |\n\n![](image.001.png)\n\nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n12 December 2007\n\n| AD/CRESCO/12Appendix A | Fin Leading Edge - Inspection | 2/2008 DM |\n| ---------------------- | ----------------------------- | --------- |\n\n  \nThe attached diagram should be used to annotate the location and type of damage.\n\n![](image.002.png)\n\nTip Fairing\n\nInternal Ribs\n\nLap Joints\n\nStarboard Port\n\n  \nFigure 1 - Damage and Repair Location Diagram\n\nIndicate extent of defects, including repair doublers on the appropriate diagram. This information is necessary for the CASA and the NZ CAA to assess the overall condition of the vertical fin against its time in service.","sortOrder":0},{"sectionNumber":"AD/CRESCO/12","sectionType":"part","heading":"AD/CRESCO/12","content":"## AD/CRESCO/12","sortOrder":1},{"sectionNumber":"Fin Leading Edge - Inspection","sectionType":"part","heading":"Fin Leading Edge - Inspection","content":"## Fin Leading Edge - Inspection","sortOrder":2},{"sectionNumber":"2/2008 DM","sectionType":"part","heading":"2/2008 DM","content":"## 2/2008 DM","sortOrder":3},{"sectionNumber":"AD/CRESCO/12Appendix A","sectionType":"part","heading":"AD/CRESCO/12Appendix A","content":"## AD/CRESCO/12  \nAppendix A","sortOrder":4}],"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":3,"scope_assessment":{"changed":false,"description":"The directive's scope is limited to Cresco 08‑600 series aircraft (all serial numbers) and prescribes inspection, repair and reporting requirements. The instrument itself does not expand or narrow that applicability beyond its stated terms; it supplements local oversight with a reference to the New Zealand AD but does not alter the covered fleet or core obligations."},"complexity_factors":["Targeted applicability to a single model series but all serial numbers increases population coverage (Applicability).","Short initial compliance window (within 5 hours TIS) creates scheduling pressure for operators (Compliance).","Recurring inspection interval (every 300 hours TIS) introduces ongoing maintenance cost and record-keeping (Compliance).","Mandated removal of the dorsal fin extension and a detailed visual inspection requires access/maintenance resources and possible temporary grounding (Requirement).","Mandatory repair before further flight shifts financial and operational burden to owners/operators and can trigger downtime (Requirement).","Obligation to report damage or nil findings via the Service Difficulty Reporting System adds administrative compliance cost and data-sharing obligation (Requirement).","Requirement to annotate defect locations on Appendix A creates a data collection standard that affects assessment and potential regulatory follow-up (Appendix A).","Cross-reference to New Zealand AD adds coordination and possible differing administrative expectations across regulators (Note/Background)."],"plain_english_summary":"This Airworthiness Directive requires owners/operators of Pacific Aerospace Cresco 08‑600 series aircraft to remove the dorsal fin extension, carry out a detailed visual inspection of the fin leading edge and whole fin skin, repair defects before further flight, and report results to CASA. (Requirement; Compliance)\n\nCosts fall on owners/operators (inspection, repair, reporting); CASA enforces compliance and inspections may alter maintenance schedules or ground aircraft until repairs are made. (Background)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, targeted Airworthiness Directive addressing a specific safety defect in a specific aircraft type. The scope remains precisely focused on the fin inspection requirements arising from reported cracking incidents. There is no evidence of scope creep or expansion beyond the original safety purpose."},"complexity_factors":["Very short document (approximately 300 words of substantive content)","Only 2 main requirements with clear, sequential steps","Minimal defined terms (only standard aviation terminology like 'TIS' — Time In Service)","No cross-referencing to other legislation or complex conditional logic","Simple compliance structure: two deadlines with straightforward intervals","Single applicability criterion (specific aircraft series, all serial numbers)","Background provides clear safety rationale without legal caveats"],"plain_english_summary":"This CASA Airworthiness Directive mandates urgent inspections and repairs to the vertical fin of Pacific Aerospace Cresco 08‑600 series aircraft after discovery of serious cracking under the dorsal fin extension. Owners/operators must inspect and repair the fin and leading-edge skin, report defects, and follow recurring checks to prevent fin failure that could cause loss of control. It affects all Cresco 08‑600 airframes and is safety‑critical."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cresco-12-fin-leading-edge-inspection","history":"/api/acts/ad-cresco-12-fin-leading-edge-inspection/history","analysis":"/api/acts/ad-cresco-12-fin-leading-edge-inspection/analysis","conflicts":"/api/acts/ad-cresco-12-fin-leading-edge-inspection/conflicts","importantCases":"/api/acts/ad-cresco-12-fin-leading-edge-inspection/important-cases","documents":"/api/acts/ad-cresco-12-fin-leading-edge-inspection/documents"}}