{"id":"F2006B06777","name":"AD/SA-TP/28 - Wing Lift Strut Fretting","slug":"ad-sa-tp-28-wing-lift-strut-fretting","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114620,"registerId":"commonwealth-F2006B06777-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SA-TP/28 - Wing Lift Strut Fretting","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)  British Aerospace (Scottish Aviation) Twin Pioneer Series Aeroplanes\n\n \n\nAD/SA-TP/28 Wing Lift Strut Fretting 12/86\n\nApplicability: All models.\n\n \n\nRequirement: Modify in accordance with Scottish Aviation MNS No 965. Compliance:  Prior to the issue of a Certificate of Airworthiness.\n\nBackground: This modification is to eliminate fretting on the surface of the wing lift strut at the stabilizer strut fitting.\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","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive's scope as stated — requiring a modification for all Twin Pioneer models to eliminate fretting and tying compliance to Certificate of Airworthiness issuance — matches the text provided. There is no text in the instrument indicating a change from that stated purpose or scope."},"complexity_factors":["Instruction is short and focused: a single mandated modification (low substantive complexity).","Dependence on an external technical document (Scottish Aviation MNS No 965) increases practical complexity because that document must be obtained and interpreted.","Timing constraint (must be done before Certificate of Airworthiness is issued) creates administrative and scheduling complexity for owners/operators.","No alternative compliance or waiver procedures specified in the text provided, so enforcement is binary (done / not done).","Applicability to all models is broad but simple; no model-specific carve-outs to interpret."],"plain_english_summary":"This instrument requires every British Aerospace (Scottish Aviation) Twin Pioneer aircraft to be modified, per Scottish Aviation MNS No 965, to eliminate fretting where the wing lift strut meets the stabilizer fitting.  \n\nOwners/operators must obtain and pay for the modification (document, parts, labour, downtime); the Civil Aviation Safety Authority will withhold a Certificate of Airworthiness until the work is completed, creating a strong compliance incentive."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive from 1986 addressing a specific structural wear problem on a specific aircraft type. It has not expanded beyond its original purpose of mandating a safety modification to prevent wing strut fretting."},"complexity_factors":["Extremely short document (under 200 words)","Only 4 substantive sections: Applicability, Requirement, Compliance, and Background","No defined terms section","No cross-references to other legislation or regulations beyond the generic 'Part 39' citation","Single, unambiguous compliance action (modify per MNS No. 965)","Single, clear deadline (prior to Certificate of Airworthiness issuance)","No conditional logic, exceptions, or nested provisions"],"plain_english_summary":"**What this is:** An Airworthiness Directive (AD) — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft.\n\n**What it does:** Requires owners/operators of **British Aerospace (Scottish Aviation) Twin Pioneer aircraft** to carry out a specific modification to the wing lift strut (a structural component that helps support the wing). The modification must follow **Scottish Aviation Maintenance Note Supplement (MNS) No. 965** — a technical instruction from the manufacturer.\n\n**Who it affects:** Anyone who owns, operates, or maintains any model of the Twin Pioneer series aircraft.\n\n**Why it matters:** The directive addresses **\"fretting\"** — wear caused by repeated rubbing or vibration between metal surfaces — at the point where the wing lift strut connects to the stabilizer strut fitting. Left unchecked, this wear could weaken the aircraft structure and potentially lead to failure. The modification must be completed **before the aircraft can be issued a Certificate of Airworthiness** (the official document proving an aircraft is safe to fly).\n\n**Key deadline:** The work must be done **before** the aircraft gets its airworthiness certificate — meaning it cannot legally fly until this fix is applied."}},"importantCases":[],"_links":{"self":"/api/acts/ad-sa-tp-28-wing-lift-strut-fretting","history":"/api/acts/ad-sa-tp-28-wing-lift-strut-fretting/history","analysis":"/api/acts/ad-sa-tp-28-wing-lift-strut-fretting/analysis","conflicts":"/api/acts/ad-sa-tp-28-wing-lift-strut-fretting/conflicts","importantCases":"/api/acts/ad-sa-tp-28-wing-lift-strut-fretting/important-cases","documents":"/api/acts/ad-sa-tp-28-wing-lift-strut-fretting/documents"}}