{"id":"F2006L03875","name":"AD/AT 800/10 - Upper Rudder Hinge","slug":"ad-at-800-10-upper-rudder-hinge","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":60802,"registerId":"commonwealth-F2006L03875-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Airtractor 800 Series Aeroplanes","sectionType":"division","heading":"Airtractor 800 Series Aeroplanes","content":"### Airtractor 800 Series Aeroplanes\n\n| AD/AT 800/10 | Upper Rudder Hinge | 1/2007 |\n| ------------ | ------------------ | ------ |\n\n| Applicability: | Model AT-802 and AT-802A aircraft, serial numbers 802/802A-0001 through 802/802A-0215.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |\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 800/10","sectionType":"part","heading":"AD/AT 800/10","content":"## AD/AT 800/10","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":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard airworthiness directive with focused, original intent: address a specific mechanical failure mode in a defined aircraft fleet. No scope creep is evident."},"complexity_factors":["Short, single-purpose directive with clear applicability (specific models and serial numbers)","Only 3 main requirements with explicit cross-references to external technical documents (Snow Engineering Service Letter 247 and Process Specification 145)","Compliance dates involve conditional logic ('whichever occurs later') but are limited to three straightforward time-in-service thresholds","No nested definitions or extensive interpretation sections","Single background scenario with clear causal chain (hinge failure → rudder separation → loss of control)","Contains only 2 notes and 1 cross-reference to FAA AD (foreign regulatory alignment)"],"plain_english_summary":"This CASA Airworthiness Directive mandates owners/operators of Air Tractor AT‑802 and AT‑802A (S/N 0001–0215) to inspect, repair and ultimately reinforce the upper rudder hinge after reports of in‑flight rudder separations. It requires 100‑hour recurring inspections, immediate repair if defects are found, and installation of an external reinforcement plate (doubler) by the specified flight‑hour limit. It’s a critical safety fix to prevent loss of control."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive is consistent with its stated original purpose: to address reported in-flight rudder separations and related hinge/skin defects. It prescribes inspections, repairs, and a mandatory reinforcing modification (external doubler). It does not broaden the subject matter beyond addressing the upper rudder hinge area or add unrelated obligations; it trades recurring inspections for a one-off modification, which is a contained change in compliance method rather than an expansion of scope."},"complexity_factors":["Narrow applicability: only two models (AT-802, AT-802A) and a single serial-number range (802/802A-0001 to -0215).","Three clear, sequential requirements (inspect, repair/replace + install doubler if damage, mandatory install) with a terminating action noted.","Simple compliance timeline with two conditional deadlines using a \"whichever occurs later\" formulation (adds a small conditional logic layer).","External technical references (Snow Engineering SL No. 247 and Process Specification No. 145) and a cross-reference to FAA AD 2006-23-14 increase implementation dependence on outside documents.","A prohibition on installing rudders without the doubler adds an operational constraint beyond inspection/repair actions.","Limited number of defined terms and few nested exceptions."],"plain_english_summary":"**What this directive does**\n\n- This Airworthiness Directive (AD) applies to Airtractor AT-802 and AT-802A aeroplanes with serial numbers 802/802A-0001 through 802/802A-0215 (Applicability).\n- It requires operators to inspect the rudder/upper rudder hinge area for loose fasteners, cracks, and corrosion, and to replace any damaged parts (Requirement 1).\n- It requires installation of an \"external doubler\" (a reinforcing plate) at the upper rudder hinge either when damage is found or as a mandatory modification (Requirement 2 and 3). Once that doubler is installed, the repetitive inspection requirement ends (Note 1 to Requirement).\n- The AD also forbids installing any rudder after the effective date unless the external doubler is incorporated (Requirement 3).\n- The directive cites Snow Engineering Service Letter (SL) No. 247 (14 Aug 2005, rev. 17 May 2006) and Snow Engineering Process Specification No. 145 (6 Dec 1991) as the technical procedures to follow (Requirement).\n\n**Why it was issued (stated reason)**\n\n- The FAA reported two incidents of the rudder separating in flight at the upper attachment hinge and multiple reports of loose hinges, skin cracks, or past repairs (Background). Hinge failure can lead to loss of yaw control and can allow the rudder to contact the elevator, risking loss of pitch control.\n\n**Key compliance timings and mechanics**\n\n- If not already inspected, do the first inspection at 3,500 hours time-in-service or within 100 hours after 18 January 2007, whichever is later; then repeat inspections at intervals no greater than 100 hours until the external doubler is fitted (Compliance 1).\n- If damage is found during an inspection, replace any damaged parts with new parts and install the external doubler before further flight (Compliance 2; Requirement 2).\n- If not already done, install the external doubler by 5,000 hours time-in-service or within 100 hours after 18 January 2007, whichever is later (Compliance 3). Installing the doubler ends the inspection requirement (Note 1).\n\n**Who is affected and who pays**\n\n- Owners and operators of the specified AT-802/AT-802A serial-numbered aircraft are directly affected (Applicability).\n- They are responsible for arranging and paying for the inspections, any necessary part replacements, and the installation of the external doubler (Requirement; Compliance).\n- Maintenance organisations or licensed mechanics perform the inspections and the modification according to the cited Snow Engineering documents.\n\n**Practical effects and trade-offs**\n\n- Safety mechanism: the measure aims to reduce the risk of rudder separation by reinforcing the upper hinge and by catching early damage through regular inspections (Background; Requirement).\n- Cost and downtime: operators incur inspection labour costs and possible costs for replacement parts and the doubler installation. Aircraft will be out of service while repaired/modified.\n- Recurring vs one-off burden: until the doubler is fitted, operators must inspect every 100 hours. Installing the doubler is a one-off action that terminates the recurring inspection requirement (Requirement Note 1). That creates a trade-off between repeated inspection costs and a one-time modification cost.\n- Spare parts and maintenance choices: after the effective date, no rudder may be installed unless it has the external doubler, which affects how spare rudders are procured and stocked (Requirement 3).\n- Implementation risk and compliance: the AD relies on operators following the Snow Engineering procedures. Failure to comply risks continued exposure to the defect described by the FAA reports (Background). The AD references FAA AD 2006-23-14 for related regulatory background (Requirement Note 2).\n\n**Summary of who decides and how behaviour changes**\n\n- Regulators require the inspection/modification; licensed maintenance providers decide the method of compliance within the technical instructions cited (Snow SL No. 247 and Process Spec No. 145).\n- Operators must change behaviour by scheduling recurring inspections until the doubler is installed, replacing any damaged parts with new parts where needed, and by ensuring future rudder installations include the doubler (Requirement; Compliance).\n\n(References to specific provisions are to the directive's Applicability, Requirement, Compliance and Background sections.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-at-800-10-upper-rudder-hinge","history":"/api/acts/ad-at-800-10-upper-rudder-hinge/history","analysis":"/api/acts/ad-at-800-10-upper-rudder-hinge/analysis","conflicts":"/api/acts/ad-at-800-10-upper-rudder-hinge/conflicts","importantCases":"/api/acts/ad-at-800-10-upper-rudder-hinge/important-cases","documents":"/api/acts/ad-at-800-10-upper-rudder-hinge/documents"}}