{"id":"F2005L02086","name":"AD/AT 600/3 - Horizontal Stabiliser Attachment Eyebolts","slug":"ad-at-600-3-horizontal-stabiliser-attachment-eyebolts","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":36303,"registerId":"commonwealth-F2005L02086-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Airtractor 600 Series Aeroplanes","sectionType":"division","heading":"Airtractor 600 Series Aeroplanes","content":"### Airtractor 600 Series Aeroplanes\n\n| AD/AT 600/3 | Horizontal Stabiliser Attachment Eyebolts | 9/2005 |\n| ----------- | ----------------------------------------- | ------ |\n\n| Applicability: | Model AT-602 aircraft, with serial numbers up to and including 602-0695 that have any 7/16-inch eyebolt (part number AN47-22A) installed; aircraft with serial number 602-0703 and subsequent; and all aircraft that have any 9/16-inch eyebolt (part number 30774-1) installed.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Tighten the four eyebolts that attach the front and rear spar of the horizontal stabiliser to the respective stabiliser strut using the torque values referenced in Snow Engineering Co. Service Letter (SL) No. 129, revised 21 October 2004.2. Replace eyebolts that attach the front and rear spar of the horizontal stabiliser to the respective stabiliser strut, in accordance with SL No. 129, Issued 26 September 1994, Revised 21 October 2004.3. For aircraft with serial numbers up to and including 602-0695: As an alternative in order to use the increased replacement compliance times in Requirement 2 of this Directive, replace the steel brace assembly inside the stabiliser with a new steel brace assembly with larger bushings, and replace any 7/16-inch eyebolt with the 9/16-inch eyebolt part number 30774-1; in accordance with SL 129A, dated 7 August 2004.Do not install any 5/16-inch eyebolt (part number AN44-17A or AN44-21A), 7/16-inch eyebolt (AN47-22A or AN-47-30A), or 9/16-inch eyebolt (part number 30774-1 or 30775-1) that exceeds the corresponding cumulative hours time in service specified in Requirement 2 or 3 of this Directive.Note: FAA AD 2005-13-12 Amdt 39-14149 refers. |\n| Compliance:    | 1. Within 100 hours time in service or 12 calendar months after 1 September 2005, whichever occurs first, unless already accomplished. Tighten thereafter at intervals not to exceed 12 calendar months.2. Replace initially upon accumulating the applicable number of hours time in service specified in SL No. 129, revised 21 October 2004, or within 50 hours time in service after 1 September 2005, whichever occurs later. Replace thereafter at the intervals specified in SL No. 129, revised 21 October 2004.3. At any time after 1 September 2005. Use the applicable time in SL 129A, dated 7 August 2004. The repetitive replacement of Requirement 2 is still required.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |\n\n|             | This Airworthiness Directive becomes effective on 1 September 2005.                                                                                                                                                                                                                                                                                                                                                                              |\n| ----------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Background: | The FAA has received numerous reports of failures of horizontal stabiliser attachment eyebolts on AT-301, AT-400, and AT-602 aircraft. Engineering analysis concluded that the eyebolts failed as a result of high cycle, low-nominal stress; and most likely due to the loss of torque during service. Failure of an eyebolt could lead to an abrupt change or complete loss of pitch control and/or aircraft departure from controlled flight. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n20 July 2005","sortOrder":0},{"sectionNumber":"AD/AT 600/3","sectionType":"part","heading":"AD/AT 600/3","content":"## AD/AT 600/3","sortOrder":1},{"sectionNumber":"Horizontal Stabiliser Attachment Eyebolt","sectionType":"part","heading":"Horizontal Stabiliser Attachment Eyebolts","content":"## Horizontal Stabiliser Attachment Eyebolts","sortOrder":2},{"sectionNumber":"9/2005","sectionType":"part","heading":"9/2005","content":"## 9/2005","sortOrder":3}],"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":7,"scope_assessment":{"changed":true,"description":"The Directive applies both to specific AT-602 serial-number groups and to any aircraft fitted with certain 9/16-inch eyebolts, and it offers an alternative compliance route (brace assembly replacement) that alters allowable replacement intervals for affected aircraft (Applicability; Requirement 3; SL129A). That combination broadens applicability beyond a pure serial-number rule and changes compliance timelines for those electing the alternative."},"complexity_factors":["Multi-tiered applicability: different requirements apply by serial number ranges and by eyebolt part number (Applicability).","Cross-references to external technical documents for substantive action: SL No.129 (revised 21 Oct 2004) and SL129A (7 Aug 2004) set torque values and replacement intervals (Requirement 1–3, Compliance 1–3).","Multiple and overlapping compliance triggers: calendar time (12 months), flight hours windows (100 hours, 50 hours after effective date, and SL-specified hours), and 'at any time after' clauses for alternatives (Compliance 1–3).","Alternative compliance path: replacing an internal steel brace assembly and upsizing bushings to permit extended replacement intervals for certain serials (Requirement 3; SL129A).","Prohibitions tied to cumulative hours-in-service: forbids installing eyebolts that exceed specified cumulative hours, creating tracking and record-keeping obligations (Requirement 3).","Repetitive obligations: initial corrective action followed by mandatory recurring tightening and replacement cycles (Requirement 1–2, Compliance 1–2).","Parts specificity and mix: multiple part numbers listed for 5/16, 7/16 and 9/16 eyebolts, creating supply, compatibility and inventory implications (Requirement, Applicability).","Reference to FAA AD increases interpretative interplay between authorities and may affect accepted practices or acceptable compliance evidence (Note: FAA AD 2005-13-12).","Operational safety stakes are high: failures can cause abrupt pitch control loss, so enforcement and conservative interpretation are likely (Background)."],"plain_english_summary":"Requires owners/operators of certain Airtractor AT-602 aeroplanes (specific serial-number ranges and any aircraft fitted with specified eyebolt part numbers) to tighten and then periodically replace the four eyebolts that attach the horizontal stabiliser, using torque and replacement intervals set out in Snow Engineering Service Letters SL No.129 and SL129A. The measure creates recurring maintenance tasks, parts purchases and labour costs to reduce risk of eyebolt failure that could cause loss of pitch control."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with focused scope addressing a specific mechanical failure mode in a defined aircraft type. The original intent was to mandate inspection and replacement of failing eyebolts, and the final text maintains this narrow safety focus without expansion into unrelated systems."},"complexity_factors":["Multiple applicability categories based on serial numbers and installed parts (three distinct groups)","Cross-references to external documents: Snow Engineering Service Letter No. 129 (two different dates) and SL 129A","Conditional logic with alternative compliance paths (Requirement 3 as alternative to Requirement 2)","Multiple compliance timeframes with 'whichever occurs first/last' calculations","Specific part number references (AN47-22A, 30774-1, etc.) that require technical knowledge to interpret","Repetitive maintenance requirements (ongoing tightening and replacement intervals)"],"plain_english_summary":"This CASA Airworthiness Directive targets Air Tractor 600-series agricultural aircraft after reports of eyebolt failures that can detach the horizontal stabiliser and cause loss of pitch control. It requires affected AT‑602s (specified serial ranges and any with 9/16\" eyebolts) to have the four stabiliser eyebolts torqued on a recurring schedule, replaced within prescribed flight‑hour limits, or optionally upgraded to larger bushings/9/16\" eyebolts for extended intervals. Compliance prevents in‑flight structural failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-at-600-3-horizontal-stabiliser-attachment-eyebolts","history":"/api/acts/ad-at-600-3-horizontal-stabiliser-attachment-eyebolts/history","analysis":"/api/acts/ad-at-600-3-horizontal-stabiliser-attachment-eyebolts/analysis","conflicts":"/api/acts/ad-at-600-3-horizontal-stabiliser-attachment-eyebolts/conflicts","importantCases":"/api/acts/ad-at-600-3-horizontal-stabiliser-attachment-eyebolts/important-cases","documents":"/api/acts/ad-at-600-3-horizontal-stabiliser-attachment-eyebolts/documents"}}