{"id":"F2006B06249","name":"AD/PITTS S-2/4 - Horizontal Stabiliser Leading Edge Support Tube - Inspection and Modification","slug":"ad-pitts-s-2-4-horizontal-stabiliser-leading-edge-support-tube-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47220,"registerId":"commonwealth-F2006B06249-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PITTS S-2/4 - Horizontal Stabiliser Leading Edge Support Tube - Inspection and Modification","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Pitts S-1 and S-2 Series Aeroplanes\n\n \n\nAD/PITTS S-2/4 Horizontal Stabiliser Leading Edge Support\n\nTube - Inspection and Modification\n\nApplicability: Model S-2A with S/Nos. 2001 to 2030. Document:  Pitts SB No. 6.\n\nCompliance: Within 100 hours time in service after 31 August 1973.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n\n8/73\n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive targeting a specific known defect in a limited production run of aircraft. It has not expanded beyond its original scope — it addresses exactly what it says it does (the horizontal stabiliser support tube) for exactly the aircraft specified (S-2A, s/n 2001–2030)."},"complexity_factors":["Extremely short document — approximately 100 words of substantive content","Only one defined applicability criterion (serial number range 2001–2030)","Single cross-reference to external technical document (Pitts SB No. 6)","No nested conditions, exceptions, or alternative compliance methods","Simple binary compliance structure: inspect/modify within specified timeframe or ground aircraft","No interpretation section or defined terms"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It requires owners and operators of specific **Pitts S-2A aerobatic aircraft** (serial numbers 2001 to 2030) to inspect and modify a part called the **horizontal stabiliser leading edge support tube**.\n\n**What it does:**\n- Mandates a safety inspection and modification to prevent potential structural failure of the tail section\n- References **Pitts Service Bulletin No. 6** as the technical document containing the specific instructions\n\n**Who it affects:**\n- Owners and operators of Pitts S-2A aircraft with serial numbers 2001–2030\n- Maintenance organisations servicing these aircraft\n\n**Why it matters:**\n- The horizontal stabiliser (the small wing at the tail that keeps the plane level) is critical for flight safety\n- This AD addresses a known defect or wear pattern that could compromise aircraft control\n- Non-compliance makes the aircraft unairworthy — it cannot legally fly until the work is done\n\n**Compliance deadline:**\n- Must be completed within **100 hours of flight time** after 31 August 1973"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"Based on the text supplied, the AD sets a specific, limited scope: inspection/modification of the horizontal stabiliser leading edge support tube for Model S-2A aircraft with serial numbers 2001–2030, to be completed within the stated 100‑hour window (Applicability; Compliance). The text does not indicate any expansion or narrowing of that scope from an earlier instrument within the supplied material, so there is no evidence in this text that the scope has changed from an original intent."},"complexity_factors":["Narrow and explicit applicability (single model and limited serial-number range) reduces scope.","Single required action type (inspection and possible modification) simplifies compliance obligations.","Fixed and short compliance window (100 hours TIS after 31 August 1973) creates a clear deadline but requires prompt scheduling.","Technical details are delegated to an external document (Pitts SB No. 6), so practical complexity depends on that bulletin's content.","No multiple options, exemptions, or phased implementation described in the AD itself.","Regulatory enforcement is implicit under the civil aviation framework but specifics of penalties or certification recording are not set out in the supplied text."],"plain_english_summary":"What this instrument does\n\n- This is an airworthiness directive (AD) that requires inspection and, if necessary, modification of the horizontal stabiliser leading edge support tube on certain Pitts S-2A aircraft (see \"Applicability\"). The technical instructions for how to carry out the work are given in \"Pitts SB No. 6\" (see \"Document\").\n\nWho it applies to\n\n- Aircraft owners/operators of Model S-2A with serial numbers 2001 to 2030 (Applicability).\n\nWhat the deadline is\n\n- The required inspection/modification must be completed within 100 hours time in service after 31 August 1973 (Compliance).\n\nWhy this measure exists (as stated)\n\n- The AD directs the inspection and modification to address an identified airworthiness issue with the horizontal stabiliser leading edge support tube (the text's stated purpose is carried in the AD title and the referral to the service bulletin). The AD itself does not set out the technical cause or full engineering rationale in the text provided; it points operators to the manufacturer's Service Bulletin (Pitts SB No. 6) for the specific modification and inspection method (Document).\n\nPractical effects, who pays, and who decides\n\n- Who pays: The aircraft owner or operator must pay for the inspection and any required modification, including parts, labour, and aircraft downtime (the AD is addressed to owners/operators — Applicability + Document).\n- Who decides and carries out the work: The owner/operator must arrange for a suitably qualified maintenance organisation or certificated mechanic to follow the Service Bulletin instructions and record compliance. The AD makes the action mandatory for the listed aircraft (Applicability; Compliance; Document).\n- Behaviour change required: Affected aircraft must be inspected and, if indicated by the inspection or the Service Bulletin, modified within the stated time window. Owners/operators must schedule maintenance and keep compliance records.\n\nCosts, incentives and trade-offs to note (mechanics rather than judgement)\n\n- Direct costs (owner/operator): parts, labour, and downtime for each affected airframe. The AD creates a discrete, one-off compliance cost for the subset of aircraft listed (Applicability; Compliance).\n- Operational trade-off: Aircraft availability may be reduced while the inspection/modification is done; operators must weigh scheduling and potential reallocation of flying hours.\n- Information and implementation risk: The AD references Pitts SB No. 6 for technical details (Document). The practical burden and scope of work therefore depend on that Service Bulletin; readers must consult it for exact procedures, tolerances and parts. If the Service Bulletin requires specialised skills or parts, owners may need to source appropriate maintenance providers and components, increasing time and cost.\n- Enforcement and discretion: The AD is issued under the civil aviation regulatory framework and requires compliance within the specified timeframe (Compliance). Regulatory authorities and airworthiness inspectors enforce compliance; the AD text itself provides the mandate and points to the Service Bulletin for technical execution (Document).\n\nMarket and business effects (focused on mechanisms)\n\n- The AD affects only a small, specifically identified set of aircraft (S-2A S/Ns 2001–2030). That narrow applicability concentrates costs on those owners/operators (Applicability).\n- The requirement can create short-term demand for maintenance services and any spare parts specified by Pitts SB No. 6 (Document). This may benefit independent maintenance providers able to perform the work, subject to their capacity and the geographical distribution of affected aircraft.\n- The AD does not, in the text supplied, create ongoing recurring obligations beyond the single required inspection/modification within the specified window (Compliance). It therefore poses a one-off compliance event rather than a continuing regulatory cost, insofar as the supplied text shows.\n\nWhere to look for technical detail\n\n- The AD directs readers to Pitts SB No. 6 for the inspection and modification procedures (Document). The AD text supplied does not include the engineering drawings or step‑by‑step instructions; those are in the referenced Service Bulletin.\n\nSource references within the instrument\n\n- Applicability: Model S-2A with S/Nos. 2001 to 2030 (Applicability).\n- Technical instructions: Pitts SB No. 6 (Document).\n- Compliance schedule: Within 100 hours time in service after 31 August 1973 (Compliance)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pitts-s-2-4-horizontal-stabiliser-leading-edge-support-tube-inspection-and-modification","history":"/api/acts/ad-pitts-s-2-4-horizontal-stabiliser-leading-edge-support-tube-inspection-and-modification/history","analysis":"/api/acts/ad-pitts-s-2-4-horizontal-stabiliser-leading-edge-support-tube-inspection-and-modification/analysis","conflicts":"/api/acts/ad-pitts-s-2-4-horizontal-stabiliser-leading-edge-support-tube-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-pitts-s-2-4-horizontal-stabiliser-leading-edge-support-tube-inspection-and-modification/important-cases","documents":"/api/acts/ad-pitts-s-2-4-horizontal-stabiliser-leading-edge-support-tube-inspection-and-modification/documents"}}