{"id":"F2006B10065","name":"AD/G159/20 - Water Methanol Tank - Inspection","slug":"ad-g159-20-water-methanol-tank-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55510,"registerId":"commonwealth-F2006B10065-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/G159/20 - Water Methanol Tank - Inspection","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 ORDERS CIVIL AVIATION SAFETY AUTHORITY                            PART 105 SCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  GULFSTREAM (GRUMMAN) G.159 SERIES AEROPLANES\n\n \n\nAD/G159/20 Water Methanol Tank - Inspection 4/73\n\nApplicability: All models.\n\n \n\nDocument: Grumman Customer Bulletin No. 232.\n\n \n\nCompliance: Within 100 hours time in service after 30 April 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 \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The supplied text sets a clear scope: inspection of the water methanol tank on all Gulfstream (Grumman) G.159 models, to be completed within 100 hours in service after 30 April 1973, using Grumman Customer Bulletin No. 232. The text contains no indication that this scope has been changed from any prior or original instrument; it states the applicability, the documentary reference, and the compliance timeframe and nothing in the supplied text indicates an alteration of that scope."},"complexity_factors":["Very short directive with a single required action (inspection)","Applies to a single aircraft series but to all models (broad applicability within that type)","Relies on an external technical document (Grumman Customer Bulletin No. 232) for procedural detail","Fixed, time-based compliance window tied to flight hours after a specific date","No procedural detail, enforcement mechanism, exemptions, or recordkeeping requirements included in the text"],"plain_english_summary":"What this instrument does mechanically\n\n- Requires an inspection of the water methanol tank on Gulfstream (Grumman) G.159 series aeroplanes. (See heading and title: \"Water Methanol Tank - Inspection\".)\n- Applies to all G.159 models. (Applicability: \"All models\".)\n- Tells operators to follow Grumman Customer Bulletin No. 232 for the matter being mandated. (Document: \"Grumman Customer Bulletin No. 232\".)\n- Sets a deadline: the inspection must be done within 100 flight hours in service after 30 April 1973. (Compliance: \"Within 100 hours time in service after 30 April 1973\".)\n\nWho this affects and who pays\n\n- Aircraft operators and owners of Gulfstream (Grumman) G.159 series aeroplanes must have the inspection performed. (Applicability.)\n- Those operators/owners are the parties who will pay for reading the bulletin, performing the inspection and any follow-up work (repairs, replacement parts, maintenance labour). (Document; Compliance.)\n\nWho decides and what behaviour changes\n\n- The directive, issued under the Civil Aviation Orders framework and the Civil Aviation Safety Authority heading, imposes the requirement. The directive specifies the set of aeroplanes covered and the compliance window. (Header; Applicability; Compliance.)\n- The concrete behavioural change required is to schedule and carry out the specified inspection within the stated 100-hour window; operators must consult the referenced Grumman bulletin to determine the inspection procedure. (Document; Compliance.)\n\nWhy it matters (stated purpose and how that plays against costs and implementation)\n\n- Stated purpose: the instrument names the water methanol tank inspection as the subject; that indicates the directive’s immediate goal is to have that tank inspected. (Title/heading.)\n- Costs and incentives: the directive creates a direct compliance cost for each affected aircraft owner/operator—time off service for the aircraft, labour and any parts or repairs found necessary. Those costs are concentrated on the set of G.159 operators because Applicability covers \"All models\" of that series. (Applicability; Compliance.)\n- Implementation dependency and risk: the text does not include the inspection steps itself; it refers operators to Grumman Customer Bulletin No. 232 for the technical content. That external dependence means compliance requires access to and reliance on that bulletin; if the bulletin is not available or is unclear, operators face uncertainty about how to comply. (Document.)\n\nTrade-offs, compliance burden and effects on private activity\n\n- Opportunity cost: aircraft will need to be scheduled for inspection within the 100-hour window, which may temporarily reduce availability and produce scheduling costs for operators. (Compliance.)\n- Administrative burden: operators must locate and follow the referenced bulletin and record compliance within the timeframe; the directive text itself does not set out recordkeeping or follow-up actions. (Document; Compliance.)\n- Market effects: the instruction will increase short-term demand for maintenance labour and parts for G.159 operators; independent maintenance providers can perform the inspection, so the measure imposes business on maintenance suppliers but does not specify provider selection. (Applicability; Document.)\n- Discretion and enforcement: the directive text does not state any discretionary exemptions, approval processes, penalties, or alternative compliance paths; it sets a mandatory requirement and a fixed compliance window. (Compliance.)\n\nConcrete citation points from the text\n\n- Applicability: \"All models.\" (Applicability.)\n- Procedure reference: \"Grumman Customer Bulletin No. 232.\" (Document.)\n- Timing requirement: \"Within 100 hours time in service after 30 April 1973.\" (Compliance.)"},"kimi_summary":{"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive from 1973 addressing a specific technical inspection requirement. It has not expanded beyond its original narrow purpose of ensuring water methanol tank safety in G.159 aircraft."},"complexity_factors":["Extremely short document — only 4 substantive lines of regulatory text","No defined terms section","No cross-references to other legislation or regulations","Simple, unqualified directive: single applicability, single document reference, single compliance deadline","No conditional logic, exceptions, or nested requirements","Bare administrative format typical of 1970s aviation safety notices"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order — issued by Australia's Civil Aviation Safety Authority (CASA) for a specific type of aircraft.\n\n**What it does:**\n- Requires owners and operators of **Gulfstream (Grumman) G.159 series aeroplanes** to inspect their **water methanol tank**.\n- Water methanol injection systems were used in some older aircraft engines to boost power (especially during takeoff) by cooling the combustion process and allowing more fuel to be burned.\n\n**Who it affects:**\n- Anyone who owns or operates a Gulfstream G.159 aircraft in Australia.\n\n**What they must do:**\n- Follow the inspection procedures outlined in **Grumman Customer Bulletin No. 232**.\n- Complete the inspection **within 100 hours of flight time** after **30 April 1973**.\n\n**Why it matters:**\nAirworthiness Directives are legally binding safety instructions. Failing to comply means the aircraft cannot be considered airworthy — it would be illegal and unsafe to fly. This particular directive likely addressed a specific defect or wear issue discovered in the water methanol tank that could affect flight safety."}},"importantCases":[],"_links":{"self":"/api/acts/ad-g159-20-water-methanol-tank-inspection","history":"/api/acts/ad-g159-20-water-methanol-tank-inspection/history","analysis":"/api/acts/ad-g159-20-water-methanol-tank-inspection/analysis","conflicts":"/api/acts/ad-g159-20-water-methanol-tank-inspection/conflicts","importantCases":"/api/acts/ad-g159-20-water-methanol-tank-inspection/important-cases","documents":"/api/acts/ad-g159-20-water-methanol-tank-inspection/documents"}}