{"id":"F2006L03878","name":"AD/AT/28 - Upper Rudder Hinge","slug":"ad-at-28-upper-rudder-hinge","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":60810,"registerId":"commonwealth-F2006L03878-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Airtractor AT-300, 400 and 500 Series Ae","sectionType":"division","heading":"Airtractor AT-300, 400 and 500 Series Aeroplanes","content":"### Airtractor AT-300, 400 and 500 Series Aeroplanes\n\n| AD/AT/28 | Upper Rudder Hinge | 1/2007 |\n| -------- | ------------------ | ------ |\n\n| Applicability: | Model AT-502 and 502B aircraft, serial numbers 502/502B-0003 through502/502B-2600.Model AT-502A aircraft, serial numbers 502A-0003 through 502A-2582.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Visually inspect the rudder and vertical hinge attachment for loose fasteners; and inspect the rudder and vertical fin skins, spars, hinges, and brackets for cracks and/or corrosion, in accordance with Snow Engineering Co. Service Letter (SL) No. 247 dated 14 August 2005, revised 17 May 2006.2. If damage is detected during any inspection, replace any damaged parts with new parts, and install the external doubler at the upper rudder hinge, in accordance with SL No. 247 and Snow Engineering Co. Process Specification No. 145 dated 6 December 1991.3. Install the external doubler at the upper rudder hinge in accordance with SL No. 247 and Snow Engineering Co. Process Specification No. 145.As of the effective date of this Directive, no rudder is to be installed unless the external doubler at the upper rudder hinge is incorporated.Note 1: Installation of the external doubler at the upper rudder hinge is terminating action for the Requirement 1 inspection requirements.Note 2: FAA AD 2006-23-14 Amdt 39-14826 refers. |\n| Compliance:    | 1. Unless the initial inspection is already accomplished, upon the accumulation of 3,500 hours time in service or within 100 hours time in service after 18 January 2007, whichever occurs later. Thereafter, inspect at intervals not to exceed 100 hours time in service.2. Before further flight.3. Upon the accumulation of 5,000 hours time in service or within 100 hours time in service after 18 January 2007, whichever occurs later; unless already accomplished.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |\n|                | This Airworthiness Directive becomes effective on 18 January 2007.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |\n\n| Background: | The FAA received two reports of in-flight rudder separation from the vertical fin at the upper attach hinge area, and other reports of aircraft with loose hinges, skin cracks, or signs of repairs to the affected area. Hinge failure adversely affects ability to control yaw and has led to the rudder folding over in flight. This condition could allow the rudder to contact the elevator and affect ability to control pitch, with subsequent loss of control. |\n| ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n23 November 2006","sortOrder":0},{"sectionNumber":"AD/AT/28","sectionType":"part","heading":"AD/AT/28","content":"## AD/AT/28","sortOrder":1},{"sectionNumber":"Upper Rudder Hinge","sectionType":"part","heading":"Upper Rudder Hinge","content":"## Upper Rudder Hinge","sortOrder":2},{"sectionNumber":"1/2007","sectionType":"part","heading":"1/2007","content":"## 1/2007","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The instrument applies to the specified Airtractor models and serial number ranges and sets inspection, repair and modification requirements. The text gives no indication that the Directive alters or narrows an earlier scope; it aligns with and references the FAA AD but does not state any change in applicability or intent from the source material provided."},"complexity_factors":["Applicability limited to particular models and serial number ranges (Applicability).","Multiple compliance timeframes: initial inspection trigger, repeated 100‑hour inspections, and a later mandatory doubler installation (Compliance; Requirement).","Use of external mandatory technical documents (Snow Engineering SL No.247 and Process Specification No.145) which the AD incorporates by reference (Requirement 1–3).","Mix of immediate 'before further flight' actions and longer windowed actions (Requirement 2; Compliance).","Mandated replacement of damaged parts and installation of a structural modification (external doubler) as terminating action (Requirement; Note 1).","Prohibition on installing any rudder without the external doubler once the Directive is effective (Requirement 3).","Cross‑reference to an FAA airworthiness directive (FAA AD 2006-23-14) creating inter-jurisdictional alignment (Requirement, Note 2)."],"plain_english_summary":"**What it does:** Requires operators of Airtractor AT-502, 502A and 502B (specified serial numbers) to inspect the upper rudder hinge area for loose fasteners, cracks or corrosion, repair or replace damaged parts, and install an external doubler; no rudder may be fitted unless the doubler is incorporated.  \n\n**Who pays and why it matters:** Aircraft owners/operators must carry out the inspections, repairs and doubler installation within set flight‑hour windows. The directive follows FAA reports of in‑flight rudder separation and aims to prevent loss of control."},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with a focused, narrow scope: addressing a specific mechanical failure mode in specific aircraft models. It has not expanded beyond its original safety purpose."},"complexity_factors":["Multiple compliance deadlines based on flight hours vs calendar dates (whichever occurs later)","Three distinct requirements with different timelines (inspection, repair if damage found, mandatory modification)","References to external technical documents (Snow Engineering Service Letter No. 247 and Process Specification No. 145) that are not reproduced in the directive","Cross-reference to FAA AD 2006-23-14 for additional context","Specific serial number ranges for applicability requiring careful verification","Conditional logic: 'unless already accomplished' appears twice, creating exceptions to the compliance schedule"],"plain_english_summary":"CASA’s mandatory AD targets Air Tractor AT-502, 502A and 502B agricultural aircraft: owners/operators must inspect and, where needed, repair the upper rudder hinge and then install an external reinforcement (doubler). The action responds to reports of rudders separating in flight from cracks, corrosion or loose fasteners — a loss-of-control risk. Damaged parts must be replaced immediately and no rudder may be fitted without the reinforcement; the modification eliminates the need for ongoing repeat inspections."}},"importantCases":[],"_links":{"self":"/api/acts/ad-at-28-upper-rudder-hinge","history":"/api/acts/ad-at-28-upper-rudder-hinge/history","analysis":"/api/acts/ad-at-28-upper-rudder-hinge/analysis","conflicts":"/api/acts/ad-at-28-upper-rudder-hinge/conflicts","importantCases":"/api/acts/ad-at-28-upper-rudder-hinge/important-cases","documents":"/api/acts/ad-at-28-upper-rudder-hinge/documents"}}