{"id":"F2008L00160","name":"AD/AC-SNOW/26 - Vertical and Horizontal Stabilisers","slug":"ad-ac-snow-26-vertical-and-horizontal-stabilisers","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":72321,"registerId":"commonwealth-F2008L00160-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Ayres Thrush (Snow) Commander Series Aer","sectionType":"division","heading":"Ayres Thrush (Snow) Commander Series Aeroplanes","content":"### Ayres Thrush (Snow) Commander Series Aeroplanes\n\n| AD/AC-SNOW/26 | Vertical and Horizontal Stabilisers | 3/2008 DM |\n| ------------- | ----------------------------------- | --------- |\n\n| Applicability: | Model S2R, S2R-R1340, S2R-R1820, S2R-T11, S2R-T15, S2R-T34, S2RHG-T34, S2R-T45, S2R-T65, S2RHG-T65, S2R-G1, S2R-G5, S2R-G6, S2R-G10, andS2R-T660 aircraft, with serial numbers as listed in the Applicability section of FAA AD 2007-26-01; equipped with metal empennage part numbers 40220 or 95400 (applies to serial numbers with or without a “DC” suffix). |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. Perform a visual inspection of the vertical stabiliser attach fitting part number 40301-7, the horizontal stabiliser attach fitting, part number 40303-1/-4/-7 or 95267-1, attachment bolt, part number NAS1105-68, and the vertical fin aft spar part number 40261-24 or 95253-1, for corrosion and cracking, in accordance with Thrush Aircraft Inc. Service Bulletin No. SB-AG-45 Revision B, dated 1 June 2007, or later FAA approved revision.2. If corrosion or cracks are found in the vertical stabiliser attach fitting part number 40301-7, the horizontal stabiliser attach fitting, part number 40303-1/-4/-7 or 95267-1, attachment bolt, part number NAS1105-68, or the vertical fin aft spar part number 40261-24 or 95253-1, during any Requirement 1 inspection; accomplish the following in accordance with Thrush Aircraft Inc. Service Bulletin No. SB-AG-45 Revision B, dated 1 June 2007, or later FAA approved revision:a. Replace the vertical stabiliser attach fitting with new part number 95266-3 fitting; the horizontal stabiliser attach fitting with new part number 95267-5 fitting; and the attachment bolt with NAS6207-68; and,b. If corrosion or cracks are found in the part number 40261-24 or 95253-1 vertical fin aft spar, repair in accordance with Thrush SB-AG-45 Revision B, or replace with new part number 40261-24 or 95253-1 vertical fin aft spar.3. If no corrosion or cracks are found in the vertical stabiliser attach fitting part number 40301-7, the horizontal stabiliser attach fitting, part number40303-1/-4/-7 or 95267-1, attachment bolt, part number NAS1105-68, or the vertical fin aft spar part number 40261-24 or 95253-1 during any Requirement 1 inspection; accomplish the following in accordance with Thrush Aircraft Inc. Service Bulletin No. SB-AG-45 Revision B, dated 1 June 2007, or later FAA approved revision: |\n\n| | a. Replace the vertical stabiliser attach fitting with new part number 95266-3 fitting; the horizontal stabiliser attach fitting with new part number 95267-5 fitting; and the attachment bolt with NAS6207-68; and,b. Perform a visual inspection of the vertical fin aft spar part number 40261-24 or 95253-1 for corrosion and cracking; and,c. If corrosion or cracks are found in the part number 40261-24 or 95253-1 vertical fin aft spar, repair in accordance with Thrush SB-AG-45 Revision B, or replace with a new part number 40261-24 or 95253-1 vertical fin aft spar.Special flight permits authorised to allow aircraft to be ferried to a maintenance facility for inspection shall be limited by the following conditions:a. Hopper must be empty;b. Vne reduced to 126 m.p.h. (109 knots); and,c. No flight into known turbulence.Note: FAA AD 2007-26-01 Amdt 39-15303 refers. |\n| ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | 1. Within 50 hours time in service after 23 January 2008, and thereafter at intervals not to exceed 100 hours time in service; until compliance with Requirement 2 or Requirement 3.2. Before further flight.3. Within 2,000 hours time in service or 2 years after 23 January 2008, whichever occurs first. |\n| | This Airworthiness Directive becomes effective on 23 January 2008. |\n| Background: | The FAA received reports of cracks in the empennage of Model S2R series aircraft. Such cracking, unless detected and corrected, could result in loss of structural integrity of the vertical stabiliser. Failure of the vertical stabiliser could lead to loss of control. |\n\n![](image.001.png) \nDavid Villiers \nDelegate of the Civil Aviation Safety Authority\n\n21 January 2008","sortOrder":0},{"sectionNumber":"AD/AC-SNOW/26","sectionType":"part","heading":"AD/AC-SNOW/26","content":"## AD/AC-SNOW/26","sortOrder":1},{"sectionNumber":"Vertical and Horizontal Stabilisers","sectionType":"part","heading":"Vertical and Horizontal Stabilisers","content":"## Vertical and Horizontal Stabilisers","sortOrder":2},{"sectionNumber":"3/2008 DM","sectionType":"part","heading":"3/2008 DM","content":"## 3/2008 DM","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive adopting a foreign (FAA) safety directive for a specific aircraft type. The scope remains tightly focused on the empennage structural integrity issue as originally identified. No scope creep is evident."},"complexity_factors":["Extensive part number references (15+ specific part numbers requiring cross-referencing with manufacturer service bulletins)","Nested conditional logic: Requirement 2 (if damage found) vs Requirement 3 (if no damage found), each with sub-requirements (a, b, c)","Multiple compliance timelines running in parallel (50 hours/100 hours recurring, 'before further flight', and 2,000 hours/2 years)","Dependency on external documents: Thrush Aircraft Inc. Service Bulletin SB-AG-45 Revision B and FAA AD 2007-26-01 (not reproduced in full)","Serial number applicability matrix referencing FAA AD 2007-26-01 for complete list","Special flight permit conditions with three separate operational restrictions"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspections and corrective action for Ayres Thrush (Snow) Commander S2R-series agricultural aircraft after reports of cracking and corrosion in empennage attachment fittings and bolts. It affects owners/operators of the specified serial-numbered planes and is legally required to prevent loss of the vertical stabiliser and potential in-flight loss of control.\n\nInspections, timely replacement with improved parts, and restricted ferry-flight conditions are required; non‑compliance grounds the aircraft."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The directive limits itself to the listed S2R-series models and specific metal empennage part numbers identified (per FAA AD 2007-26-01). It prescribes inspection, repair or replacement and ferry restrictions to address reported empennage cracking; it does not expand coverage beyond the stated models/parts or add unrelated obligations."},"complexity_factors":["Multiple specific aircraft models and serial-number applicability tied to FAA AD 2007-26-01","Numerous precise part numbers for fittings, spars and bolts (inspect/replace/repair options)","Layered compliance schedule: initial 50-hour window, recurring 100‑hour intervals, and mandatory action within 2,000 hours or 2 years","Choice-driven compliance: repair or replace affected aft spar; mandatory replacement of fittings/bolt in other cases","Dependence on Thrush Service Bulletin SB-AG-45 Rev B (or later FAA-approved revision) for inspection/repair procedures","Operational constraints for special flight permits (empty hopper, reduced Vne, no known turbulence) limit ferrying options","Technical inspection requirement (visual detection of corrosion/cracking) creates reliance on maintenance judgement and potential variability in detection"],"plain_english_summary":"Requires operators of specified Ayres Thrush (Snow) Commander S2R-series aeroplanes with metal empennage fittings to conduct recurring visual inspections of certain vertical- and horizontal-stabiliser attach fittings, attachment bolt and the vertical fin aft spar, and to repair or replace those parts when corrosion or cracking is found. Replacement of specified fittings/bolts is mandated if not previously corrected, with deadlines and limited ferry-flight conditions to reach maintenance.\n\nThis measure responds to reported empennage cracking that could cause loss of the vertical stabiliser; operators pay for inspections, parts and repairs, must meet set time limits (50/100/2,000 hours or 2 years) and follow ferry restrictions."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-ac-snow-26-vertical-and-horizontal-stabilisers","history":"/api/acts/ad-ac-snow-26-vertical-and-horizontal-stabilisers/history","analysis":"/api/acts/ad-ac-snow-26-vertical-and-horizontal-stabilisers/analysis","conflicts":"/api/acts/ad-ac-snow-26-vertical-and-horizontal-stabilisers/conflicts","importantCases":"/api/acts/ad-ac-snow-26-vertical-and-horizontal-stabilisers/important-cases","documents":"/api/acts/ad-ac-snow-26-vertical-and-horizontal-stabilisers/documents"}}