{"id":"F2006B02207","name":"AD/AC-SNOW/16 Amdt 1 - Rudder Horn Balance/Leading Edge Intersection","slug":"ad-ac-snow-16-amdt-1-rudder-horn-balance-leading-edge-intersection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41437,"registerId":"commonwealth-F2006B02207-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AC-SNOW/16 Amdt 1 - Rudder Horn Balance/Leading Edge Intersection","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)  \nAyres Thrush (Snow) Commander Series Aeroplanes\n\nAD/AC-SNOW/16\n\nAmdt 1\n\n  \n\nRudder Horn Balance/Leading Edge Intersection\n\n  \n10/88\n\nApplicability: All models S-2D and S-2R modified in accordance with Part 2 of AD/AC-SNOW/12. Requirement: 1. Remove the rudder from the aircraft.\n\n    2. Strip the fabric and dope from the intersection of the horn balance and the rudder leading edge in the region of the top hinge.\n\n    3. Inspect the intersection for cracking using a 10x glass paying particular attention to the hinge reinforcement weld edge.\n\n    4. If cracking is found repairs are to be carried out in accordance with AC 43.13 or a scheme approved by the Authority.\n\nNote: Findings for all aircraft are to be reported to local airworthiness offices of the Authority.\n\nCompliance: Within 10 hours’ time in service after 8 February 1988.\n\nBackground: The initial issue of the Directive was a one-time inspection pending an accident investigation for any further action. As a result of that accident investigation the Background is amended to note that the failure of the rudder structure in the area of the hinge modification has been attributed to undiscovered/unrectified cracking present at the time of the AD/AC-SNOW/12 modification. The undiscovered cracking continued to grow until rudder structural failure was inevitable.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1664},"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment updates the background explanation to incorporate findings from a completed accident investigation, clarifying why the inspection is necessary. However, the core scope—requiring inspection of the rudder hinge area for cracks—remains consistent with the original directive's intent."},"complexity_factors":["Technical aviation terminology requiring specialized knowledge (rudder horn balance, fabric and dope, weld edge inspection)","Cross-reference to previous airworthiness directive AD/AC-SNOW/12 for applicability","Reference to technical standard AC 43.13 for repair procedures","Specific inspection methodology requiring 10x magnification"],"plain_english_summary":"This AD mandates an urgent safety inspection for Ayres Thrush and Snow Commander S-2D/S-2R agricultural aircraft previously modified under AD/AC-SNOW/12. Owners/operators must have the rudder removed, fabric at the horn-balance leading edge stripped, and the area examined with 10x magnification for cracks; findings must be reported and any cracks repaired with approved methods. The action responds to an accident where hidden cracks led to rudder separation and must be done within 10 flight hours after 8 Feb 1988."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ac-snow-16-amdt-1-rudder-horn-balance-leading-edge-intersection","history":"/api/acts/ad-ac-snow-16-amdt-1-rudder-horn-balance-leading-edge-intersection/history","analysis":"/api/acts/ad-ac-snow-16-amdt-1-rudder-horn-balance-leading-edge-intersection/analysis","conflicts":"/api/acts/ad-ac-snow-16-amdt-1-rudder-horn-balance-leading-edge-intersection/conflicts","importantCases":"/api/acts/ad-ac-snow-16-amdt-1-rudder-horn-balance-leading-edge-intersection/important-cases","documents":"/api/acts/ad-ac-snow-16-amdt-1-rudder-horn-balance-leading-edge-intersection/documents"}}