{"id":"F2006B02212","name":"AD/AC-SNOW/21 - Vertical Tail Attachment Bracket","slug":"ad-ac-snow-21-vertical-tail-attachment-bracket","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41442,"registerId":"commonwealth-F2006B02212-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AC-SNOW/21 - Vertical Tail Attachment Bracket","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/21 Vertical Tail Attachment Bracket 1/94\n\nApplicability: Models Serial Numbers\n\nS2R 5000 through 5099, 1380R, and 1416R through 2583R\n\nS2R-R1340 R1340-001 through R1340-030 (with or without DC suffix) S2R-R3S R3S-001 through R3S-011 (with or without DC suffix) S2R-R1820 R1820-001 through R1820-035 (with or without DC suffix) S2R-T11 T11-001 through T11-005 (with or without DC suffix)\n\nS2R-T15 T15-001 through T15-029 (with or without DC suffix) and T27- 001 through T27-029,, and T27-031 (with or without DC suffix)\n\nS2R-T34 6000 through 6049, T34-001 through T34-180, T34-190, T34-\n\n191, and T34-192 (with or without DC suffix) T36-001 through T36-180 (with or without DC suffix); and T41-001 through T41- 180 (with or without DC suffix)\n\nS2R-T45 T45-001 through T45-003 (with or without DC suffix) S2R-T65 T65-001 (with or without DC suffix)\n\nS2R-HG-T65 T65-002 through T65-010 (with or without DC suffix) S2RG6 G6-101 through G6-112\n\nS2R-G10 G10-101\n\nRequirement: 1. Inspect the bracket that attaches the vertical tail front spar to the horizontal stabiliser for damage (cracks, broken lugs or bolts, or elongated holes) in accordance with the Accomplishment Instructions: I. Inspection, section of Ayres Service Bulletin SB-AG-32.\n\nIf any damage is found to the bracket during the inspection specified above, replace the bracket with an aluminium bracket, part number 40301T007, and install a new close out plate, part number 40309T003, in accordance with the Accomplishment Instructions: II. Repair, section of Ayres Service Bulletin SB-AG-32.\n\n2. Replace the bracket with an aluminium bracket, part number 40301T007, and install a new close out plate, part number 40309T003, in accordance with Accomplishment Instructions: II. Repair, section of Ayres Service Bulletin SB-AG-32.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nThe replacement may be accomplished instead of the inspection specified in Requirement 1 of this Directive provided it is accomplished at or prior to the 50 hours’ time in service compliance time.\n\nNote: FAA AD 93-20-05 Amdt 39-8713 refers.\n\nCompliance: 1. Within 50 hours’ time in service after 6 January 1994.\n\n2. Unless already accomplished, within 100 hours’ time in service after 6 January 1994.\n\nBackground: There have been reports of broken lugs or bolts on the vertical tail attachment bracket on a significant number of aircraft.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific structural defect in a defined aircraft fleet. The scope remains tightly focused on the vertical tail attachment bracket issue as originally identified."},"complexity_factors":["Multiple model variants with overlapping and non-sequential serial number ranges (e.g., '5000 through 5099, 1380R, and 1416R through 2583R')","Cross-reference to external technical document (Ayres Service Bulletin SB-AG-32) for detailed accomplishment instructions","Conditional compliance path allowing replacement instead of inspection if done within 50 hours","Dual compliance deadlines (50 hours for inspection/optional replacement, 100 hours for mandatory replacement)","Reference to corresponding FAA Airworthiness Directive (93-20-05) for additional context","Specific part numbers required for replacement components (40301T007, 40309T003)"],"plain_english_summary":"This CASA Airworthiness Directive mandates owners/operators of specified Ayres Thrush (Snow) Commander serials to address cracking of the bracket that secures the vertical tail to the horizontal stabiliser. Because bracket failure can cause loss of control, you must inspect and, if damaged, replace it — or replace it immediately — within 50 flight hours after 6 Jan 1994 (or at latest 100 flight hours). Compliance is mandatory to keep the aircraft legal to fly."},"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":true,"description":"The Directive moves from a reactive inspection-and-repair approach to a fleet-wide mandatory replacement requirement. Requirement 1 mandates inspection and repair of damaged brackets; Requirement 2 mandates replacement of the bracket and close-out plate for affected aircraft unless already done. Compliance times (50 and 100 hours after 6 January 1994) force operators to replace brackets across the listed serial ranges within set timeframes. Consequences: aircraft owners/operators bear parts and labour costs and must schedule maintenance; certificated maintenance organisations perform the work per SB-AG-32; the Note allows replacement to substitute for inspection if done within 50 hours, concentrating the compliance burden into a short window."},"complexity_factors":["Many specific models and serial-number ranges are listed in Applicability, increasing administrative effort to determine affected aircraft.","Compliance relies on an external technical document (Ayres Service Bulletin SB-AG-32) for inspection and repair procedures; required actions are not fully set out in the Directive text.","Two compliance pathways: (a) inspect and repair damaged brackets, or (b) replace bracket outright (may substitute for inspection if done within 50 hours), which creates scheduling and decision trade-offs for operators (Requirement 1 and Note).","Prescribed replacement parts are identified by part numbers (40301T007 bracket; 40309T003 close out plate), requiring parts procurement and fitment logistics (Requirement 1–2).","Two discrete compliance time limits (50 hours for initial inspection or replacement; 100 hours for mandatory replacement if not yet done) add coordination complexity (Compliance).","Cross-reference to FAA AD 93-20-05 adds an external regulatory linkage to consider for operators and maintainers (Note)."],"plain_english_summary":"This Airworthiness Directive requires operators of specified Ayres Thrush (Snow) Commander aeroplanes to inspect the vertical-tail front-spar attachment bracket for cracks, broken lugs/bolts or elongated holes and to replace any damaged bracket with aluminium part 40301T007 and close‑out plate 40309T003 per Ayres Service Bulletin SB-AG-32. Operators may instead replace the bracket without inspecting; inspections must be done within 50 hours and replacements within 100 hours after 6 January 1994."}},"importantCases":[],"_links":{"self":"/api/acts/ad-ac-snow-21-vertical-tail-attachment-bracket","history":"/api/acts/ad-ac-snow-21-vertical-tail-attachment-bracket/history","analysis":"/api/acts/ad-ac-snow-21-vertical-tail-attachment-bracket/analysis","conflicts":"/api/acts/ad-ac-snow-21-vertical-tail-attachment-bracket/conflicts","importantCases":"/api/acts/ad-ac-snow-21-vertical-tail-attachment-bracket/important-cases","documents":"/api/acts/ad-ac-snow-21-vertical-tail-attachment-bracket/documents"}}