{"id":"F2006B06774","name":"AD/SA-TP/25 - Main Fuel Tank Vent Pipes","slug":"ad-sa-tp-25-main-fuel-tank-vent-pipes","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114615,"registerId":"commonwealth-F2006B06774-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SA-TP/25 - Main Fuel Tank Vent Pipes","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/25 Main Fuel Tank Vent Pipes NK\n\nApplicability: All models.\n\n \n\nDocument: Scottish Aviation TNS No. 47.\n\n \n\nCompliance: Modify forthwith. Inspect whenever the mainplane is assembled to the centre section.\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 \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive for a specific aircraft type. It has not expanded beyond its original purpose of addressing fuel tank vent pipe safety in Twin Pioneer aircraft."},"complexity_factors":["Extremely short document — only 4 substantive lines of regulatory content","No defined terms section; all language is plain operational English","Single cross-reference to external technical document (Scottish Aviation TNS No. 47)","No conditional logic, exceptions, or nested provisions","Simple binary compliance structure: one-time modification + recurring inspection trigger","No penalty provisions, appeal mechanisms, or administrative procedures included"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998.\n\n**What it does:** It requires owners and operators of **British Aerospace (Scottish Aviation) Twin Pioneer series aeroplanes** to:\n- **Modify** the main fuel tank vent pipes immediately (\"forthwith\")\n- **Inspect** these vent pipes whenever the mainplane (the wing structure) is attached to the centre section of the aircraft\n\n**Who it affects:** Anyone who owns, operates, or maintains Twin Pioneer aircraft — a British-built twin-engine utility aircraft from the 1950s-60s.\n\n**Why it matters:** Fuel tank vent pipes prevent dangerous pressure build-ups or vacuum conditions in fuel tanks. A fault here could cause fuel starvation, leakage, or fire. The directive references **Scottish Aviation TNS No. 47** — a technical notice from the original manufacturer specifying exactly what modifications and inspections are required.\n\n**The bottom line:** If you fly or maintain one of these specific vintage aircraft, you must follow this safety order to keep the aircraft legally airworthy."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive's stated scope is a universal applicability to all Twin Pioneer models and mandates modification plus recurring inspections. The text contains no indication that this scope has been expanded or narrowed relative to an earlier or original intent; it reads as a single, self-contained requirement referring to TNS No. 47 for technical details."},"complexity_factors":["Very short and prescriptive text (low internal complexity).","Broad applicability to all models increases operational footprint despite simple wording.","Key technical detail and procedures are deferred to an external document (Scottish Aviation TNS No. 47), requiring cross-reference.","Use of non‑precise timing language (\"forthwith\") creates limited discretion about scheduling.","Event‑based inspection trigger (assembly to centre section) requires integration into maintenance workflows."],"plain_english_summary":"### What this directive does, in plain terms\n\n- Mechanically, the directive orders that the main fuel tank vent pipes on British Aerospace (Scottish Aviation) Twin Pioneer series aeroplanes be modified immediately and that an inspection be carried out each time the mainplane is assembled to the centre section. (See: \"Compliance: Modify forthwith. Inspect whenever the mainplane is assembled to the centre section.\")\n\n- It applies to all models of the Twin Pioneer series. (See: \"Applicability: All models.\")\n\n- The technical steps or drawings are not contained in the text of the directive itself; the AD refers operators and maintainers to Scottish Aviation TNS No. 47 for the controlling technical instructions. (See: \"Document: Scottish Aviation TNS No. 47.\")\n\n### Who decides and who must act\n\n- The Civil Aviation Safety Authority (under the Schedule of Airworthiness Directives, Civil Aviation Regulations 1998, Part 39) is the issuing authority for this AD. The text of the AD imposes mandatory action on operators/owners of the affected aeroplanes. (See heading: \"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\" and the AD text.)\n\n- Aircraft owners/operators and their maintenance organisations must carry out the modification immediately and perform the stated inspections at each reassembly event. The AD itself does not allocate funding or supply parts.\n\n### Stated or implied purpose and how that maps to costs and incentives\n\n- The AD text does not contain an explicit statement of the event or failure that prompted it; it simply prescribes modification and recurring inspection. The reference to a Scottish Aviation technical note (TNS No. 47) indicates that the detailed safety or maintenance rationale and the technical remedy are recorded there. (See: \"Document: Scottish Aviation TNS No. 47.\")\n\n- Practical consequences for operators: they must arrange for the modification to be done immediately (which creates an immediate expense of labour, parts and aircraft downtime) and they must perform inspections whenever the mainplane is assembled to the centre section (an ongoing operational/maintenance burden tied to each assembly). The AD text does not estimate the cost or time for modification or inspection.\n\n- Incentives and behaviour: because compliance is mandatory, operators will prioritise the modification and set up inspection procedures tied to mainplane assembly events. Lack of technical detail in the AD means operators will need to obtain and follow TNS No. 47 (additional administrative step and potential cost). The AD does not create a subsidy or funding mechanism; the cost falls to operators/owners and their approved maintenance organisations.\n\n### Implementation, discretion and compliance risks\n\n- Timing language: the AD uses the term \"forthwith\" for the modification, which is immediate but not numerically defined in days or flight hours. That leaves a limited procedural discretion for how quickly operators schedule the work, but the mandate is unambiguous that the modification must be done without delay. (See: \"Modify forthwith.\")\n\n- The inspection requirement is event-triggered (on assembly to the centre section), which is a clear operational trigger but requires operators to ensure inspection procedures are embedded in their maintenance/assembly checklists. (See: \"Inspect whenever the mainplane is assembled to the centre section.\")\n\n- Because the AD text is terse and defers technical detail to TNS No. 47, implementation depends on access to and interpretation of that external technical document. The AD does not itself describe acceptable alternatives, nor does it document any approval process for deviations within the text provided.\n\n### Net summary\n\n- This Airworthiness Directive mandates an immediate physical modification of main fuel tank vent pipes and recurring inspections tied to mainplane assembly, applies to all Twin Pioneer models, and points to Scottish Aviation TNS No. 47 for technical detail. The directive places the financial, administrative and operational burden of compliance on aircraft owners/operators and their maintenance organisations, while leaving certain implementation specifics to the referenced technical note."}},"importantCases":[],"_links":{"self":"/api/acts/ad-sa-tp-25-main-fuel-tank-vent-pipes","history":"/api/acts/ad-sa-tp-25-main-fuel-tank-vent-pipes/history","analysis":"/api/acts/ad-sa-tp-25-main-fuel-tank-vent-pipes/analysis","conflicts":"/api/acts/ad-sa-tp-25-main-fuel-tank-vent-pipes/conflicts","importantCases":"/api/acts/ad-sa-tp-25-main-fuel-tank-vent-pipes/important-cases","documents":"/api/acts/ad-sa-tp-25-main-fuel-tank-vent-pipes/documents"}}