{"id":"F2006B05260","name":"AD/CESSNA 206/54 Amdt 2 - Horizontal Stabilizer Front Spar","slug":"ad-cessna-206-54-amdt-2-horizontal-stabilizer-front-spar","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":45612,"registerId":"commonwealth-F2006B05260-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 206/54 Amdt 2 - Horizontal Stabilizer Front Spar","content":"![](image.001.png)\n\n![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nOn the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/CESSNA 206/54 Amdt 1 and issues the following AD under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)\n\nCessna 206 Series Aeroplanes\n\nAD/CESSNA 206/54\n\nAmdt 2\n\n  \nHorizontal Stabilizer Front Spar 9/2004\n\nApplicability: All models of Cessna 206 aircraft.\n\nRequirement: Visually inspect the front and rear faces of horizontal stabilizer front spar assembly centre section for cracks around the cut-out in the front spar web. Refer to Figure 1 below.\n\nIt should be noted that for models manufactured from 1968 onwards the horizontal stabiliser front spar would be of a three-layer design. This means that the centre laminate will effectively be hidden by the two outer laminates, making inspection of the centre laminate almost impracticable. The centre laminate should be inspected as far as practicable without disassembly of the spar.\n\nAny cracks in the front spar web must be repaired before further flight, and a defect report must be submitted.\n\nNote 1: Access can be achieved by the removal of the fillet fairing. The front face of the front spar is easily seen. The rear face may be seen via a hole in the upper surface of the horizontal stabilizer using an inspection mirror and torch.\n\nNote 2: This inspection may require some experimenting with lights and mirrors to obtain some certainty in the results of the inspection. The inspection would be much easier to conduct with the use of a borescope.\n\n![](image.002.png)\n\nCompliance: a. For aircraft with less than 10000 hours time in service, inspect before exceeding 10000 hours total time in service, and thereafter at intervals not exceeding 110 hours time in service.\n\nb. For aircraft with 10000 or more hours time in service, inspect before 18 March 2002, and thereafter at intervals not exceeding 110 hours time in service.\n\nThis Amendment becomes effective on 2 September 2004.\n\nBackground: Reports have been received of cracking of the horizontal stabilizer front spar on Australian registered Cessna 210s. Both front and rear spars must be serviceable for the horizontal stabilizer to carry ultimate load. The front spar forms part of the horizontal stabilizer’s primary load path, and loss of strength in this area could be catastrophic.\n\nIt should be noted that this Airworthiness Directive mandates an inspection requirement already stated in the manufacturer’s maintenance data.\n\nAmendment 1 of this Airworthiness Directive was issued to highlight that later models have been manufactured with horizontal stabiliser spars containing three layers, making the centre laminate almost impossible to inspect. This amendment provided guidance on inspection of the three layer configuration. Compliance times were unchanged.\n\nAmendment 2 of this Airworthiness Directive is issued to increase the recurrent compliance interval from 100 hours to 110 hours time in service to allow the inspections required by this Airworthiness Directive to be aligned with scheduled maintenance.\n\n![](image.003.png)  \nThe original issue of this Airworthiness Directive became effective on 6 March 2002\\. Amendment 1 of this Airworthiness Directive became effective on 1 December 2003.\n\nDavid Villiers\n\nDelegate of the Civil Aviation Safety Authority 21 July 2004\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 11 August 2004","sortOrder":0}],"analysis":{"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"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment maintains the original scope of inspecting horizontal stabilizer front spars for cracks. The only modification is a minor administrative adjustment to the recurring inspection interval (100 to 110 hours) to align with maintenance schedules. The core safety purpose and applicability remain unchanged from the original 2002 directive."},"complexity_factors":["Short, single-purpose directive with clear applicability (all Cessna 206 models)","Simple conditional structure: two compliance paths based on flight hours (10,000 hour threshold)","Only 1 defined term implicitly used ('time in service')","Minimal cross-referencing (only refers to manufacturer's maintenance data in background)","Contains practical guidance notes (Notes 1 and 2) rather than legal subsections","Single amendment purpose clearly stated (interval change from 100 to 110 hours)","No nested exceptions or complex definitional sections"],"plain_english_summary":"This safety order requires Australian owners, operators and maintenance engineers of Cessna 206 aircraft to visually inspect the horizontal stabilizer front spar for cracking on a recurring schedule tied to airframe hours, ground the aircraft until repairs if cracks are found, and report defects. Cracking could cause catastrophic tail failure because the spar is a primary load path; hidden middle layers make inspection difficult. Amendment 2 only extends the recurring inspection interval from 100 to 110 hours."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment does not expand the AD's substantive scope beyond its original purpose (detect and remedy cracks in the horizontal stabilizer front spar). It refines inspection guidance for three-layer spars (Amendment 1) and modestly lengthens the recurrent inspection interval from 100 to 110 hours to better align with scheduled maintenance (Amendment 2). These are adjustments to implementation and timing rather than a significant broadening of the AD's coverage or functions."},"complexity_factors":["Short, single-topic directive (horizontal stabilizer front spar inspection)","Limited conditional logic: two compliance branches based on total hours (<10000 and ≥10000)","One technical complication: three-layer spar configuration makes centre laminate hard to inspect (Amendment 1)","Cross-reference to manufacturer's maintenance data (Background)","Few procedural details but practical access notes (Note 1, Note 2)","No defined-term heavy interpretation section or multiple nested exceptions"],"plain_english_summary":"**What this instrument does (mechanically):**\n\n- It requires owners/operators of all Cessna 206 aeroplanes to visually inspect the front and rear faces of the horizontal stabilizer front spar centre section for cracks around the cut‑out in the front spar web (Requirement).  \n- If any cracks are found, the aircraft must be repaired before further flight and a defect report must be submitted (Requirement).  \n- Access guidance is given: remove the fillet fairing to see the front face; the rear face can be viewed through an access hole with mirror/torch or a borescope (Note 1, Note 2).  \n\n**Who this affects:**\n\n- All operators and owners of Cessna 206 aircraft (Applicability).  \n- Maintenance personnel who carry out inspections and repairs on those aircraft.  \n\n**When inspections must be done (compliance timing):**\n\n- Aircraft with less than 10,000 hours total time in service: inspect before exceeding 10,000 hours, then repeat at intervals not greater than 110 hours time in service (Compliance a).  \n- Aircraft with 10,000 or more hours time in service: inspect before 18 March 2002, then repeat at intervals not greater than 110 hours time in service (Compliance b).  \n- Amendment 2 changed the recurrent interval from 100 hours to 110 hours to allow alignment with scheduled maintenance (Background / Amendment 2).  \n\n**Why the requirement exists (stated purpose):**\n\n- The Airworthiness Directive says reports were received of cracking of the horizontal stabilizer front spar on Australian Cessna 210s and that the front spar is part of the stabilizer's primary load path; loss of strength here could be catastrophic (Background).  \n- The AD also notes it enforces an inspection already contained in the manufacturer's maintenance data (Background).\n\n**Practical details and limitations:**\n\n- Later-model spars (from 1968 onwards) are three-layer laminates; the centre laminate is effectively hidden by the two outer laminates, so inspecting the centre layer without disassembling the spar is described as \"almost impracticable.\" The AD therefore requires inspection \"as far as practicable\" without disassembly (Requirement / Amendment 1).  \n- The AD recommends using lights, mirrors, or a borescope to improve inspection certainty (Note 2).  \n\n**Who pays and who decides:**\n\n- Aircraft owners/operators bear inspection and repair costs, including possible borescope use, fillet fairing removal, repair labour, parts, downtime and the administrative cost of submitting defect reports.  \n- The Civil Aviation Safety Authority (CASA) delegate issued the AD under regulatory power (pursuant to subregulation 39.1(1) of CASR 1998) and sets the compliance timing and required actions (preamble).\n\n**Costs, trade-offs and implementation risks (tested against the AD's stated purpose):**\n\n- Costs and incentives: The AD imposes recurring inspection cost and downtime on owners/operators. Using a borescope or removing fairings increases labour/time; repairs will vary in cost depending on crack severity. Those costs are concentrated on affected aircraft owners; safety benefits are diffuse (risk reduction for users and occupants).  \n- Trade-offs and alignment: Increasing the recurrent interval from 100 to 110 hours reduces inspection frequency marginally and is stated to better align the inspections with scheduled maintenance (Background / Amendment 2). That lowers recurring cost but slightly delays detection compared with the previous 100‑hour interval.  \n- Residual risk from three‑layer spars: For aircraft with the three‑layer spar design, the AD accepts an inspection that may not reveal defects in the hidden centre laminate (Requirement / Amendment 1). Without disassembly the AD relies on ‘‘inspect as far as practicable,’’ which may leave some defects undetected until deeper repairs or disassembly occur. This is an implementation limitation acknowledged in the AD.  \n- Enforcement and discretion: The AD prescribes action and timing; repair before further flight is mandatory if cracks are found, and a defect report must be made. CASA enforces compliance under its regulatory powers.  \n- Opportunity costs: Time spent on inspections may displace other maintenance tasks or operational flying; owners choose between performing inspections in‑house or using paid maintenance providers.  \n- Substitution effects: Operators might schedule inspections to coincide with other maintenance to reduce total downtime (explicitly encouraged by the 110‑hour interval alignment).  \n\n**Bottom line:** This AD makes a mandatory inspection and reporting requirement for the front spar of the horizontal stabilizer on all Cessna 206s, requires repair before further flight if cracks are found, and slightly relaxes the recurrent inspection frequency (from 100 to 110 hours) to align with scheduled maintenance. The AD acknowledges practical inspection limits for three‑layer spar designs and directs operators to use visual aids or borescopes where needed (Applicability; Requirement; Compliance; Notes; Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-206-54-amdt-2-horizontal-stabilizer-front-spar","history":"/api/acts/ad-cessna-206-54-amdt-2-horizontal-stabilizer-front-spar/history","analysis":"/api/acts/ad-cessna-206-54-amdt-2-horizontal-stabilizer-front-spar/analysis","conflicts":"/api/acts/ad-cessna-206-54-amdt-2-horizontal-stabilizer-front-spar/conflicts","importantCases":"/api/acts/ad-cessna-206-54-amdt-2-horizontal-stabilizer-front-spar/important-cases","documents":"/api/acts/ad-cessna-206-54-amdt-2-horizontal-stabilizer-front-spar/documents"}}