{"id":"F2006B10091","name":"AD/G159/5 Amdt 2 - APU Turbine Wheel - Inspection","slug":"ad-g159-5-amdt-2-apu-turbine-wheel-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55571,"registerId":"commonwealth-F2006B10091-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/G159/5 Amdt 2 - APU Turbine Wheel - 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/G159/5 Amdt 2 APU Turbine Wheel - Inspection 11/7\n\n1\n\n \n\nApplicability: All models.\n\n \n\nDocument: 1. Airesearch SB No. 49-1045; or\n\n \n\n2. Grumman Customer Bulletin No. 180; or 3. FAA AD 65-9-3.\n\nCompliance: At intervals not exceeding 250 hours of APU operation or 500 APU starts, whichever occurs first.\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 contains a single, self-contained directive applying to all G.159 models and setting inspection intervals; it does not indicate any change from an earlier or original scope within the provided material. No modification of applicability or inspection scope is stated in the text supplied."},"complexity_factors":["Short, narrowly focused directive specifying a single inspection requirement (low intrinsic legal complexity).","Mandatory external references: compliance requires consulting one of three technical documents (adds operational complexity and dependency on external procedural detail).","Two-part compliance metric (APU hours or APU starts) requires accurate operational tracking systems for operators.","Lack of remedial detail in the AD itself—inspect/repair actions are in referenced documents—so users must cross-reference multiple sources to implement.","Clear applicability to all models reduces ambiguity about which aircraft are covered."],"plain_english_summary":"What this instrument requires\n\n- This airworthiness directive (AD) requires periodic inspection of the auxiliary power unit (APU) turbine wheel on Gulfstream (Grumman) G.159 series aeroplanes. (See heading and title: \"APU Turbine Wheel - Inspection\".)\n\nWho it applies to\n\n- It applies to all G.159 models. (Applicability)\n\nHow compliance works mechanically\n\n- The AD mandates that inspections be carried out in accordance with one of the listed source documents: Airesearch SB No. 49-1045, Grumman Customer Bulletin No. 180, or FAA AD 65-9-3. (Document)\n- Inspections must occur at intervals not exceeding 250 hours of APU operation or 500 APU starts, whichever comes first. (Compliance)\n\nWho pays and who decides\n\n- The operator or owner of each affected aircraft must arrange and pay for the inspections, and for any repairs or part replacements discovered by those inspections. The Civil Aviation Safety Authority issues the directive; the referenced technical documents specify the inspection procedures to be followed. (Title/Header; Document)\n\nWhy the directive exists (stated and implied purpose)\n\n- The text requires inspections of the APU turbine wheel. The instrument’s explicit mechanism is to create a mandatory inspection schedule and to direct operators to specified technical documents for the inspection procedure. The implied objective (drawn from the subject matter) is to identify damage or wear on the turbine wheel before it leads to in-service failure; the AD achieves this by setting fixed inspection intervals and referencing detailed inspection instructions. (Title; Compliance; Document)\n\nTrade-offs, costs, incentives and implementation issues\n\n- Direct compliance cost is borne by operators: performing inspections, removing and reinstalling the APU if required, material and labour for any remedial work, and aircraft downtime while inspections/repairs are performed. (Compliance; Document)\n- The inspection interval creates an operational constraint: operators must track APU hours and starts to know when inspections are due. This imposes record-keeping and scheduling effort. (Compliance)\n- The AD does not specify exact inspection steps itself; it refers to external technical documents for the procedure. That centralises procedural detail in the referenced documents and gives the issuer of those documents (Airesearch/Grumman/FAA) practical control over how compliance is performed. Operators must obtain and follow those documents. (Document)\n- Because the AD mandates inspections at a fixed interval (hours or starts), it creates an incentive for earlier replacement or repair if inspections find marginal defects. It may also lead operators to prefer equipment or operational practices that reduce APU starts/hours to delay inspections, where that is feasible. (Compliance)\n- The AD sets a clear, objective compliance metric (hours or starts) which aids enforceability but does not itself authorize discretionary alternatives or deviations; any variation would need to be authorised under whatever approval process the regulator provides outside this instrument. (Compliance)\n\nPractical effects on private choice and markets\n\n- The directive affects maintenance scheduling and costs for operators of affected aeroplanes. It changes the timing of maintenance expenditure (bringing forward or formalising inspections) and may influence spare-parts demand for APU turbine wheels if inspections recommend replacements. (Compliance; Document)\n\nLimitations in the text provided\n\n- The AD text is short and does not include the inspection procedures, findings thresholds, or remedial actions; those are contained in the referenced documents. Therefore operational detail, the cost of typical remedial actions, and enforcement mechanisms are not stated in the AD itself and must be read in the cited documents. (Document)\n\nSource citations within the instrument\n\n- Applicability: \"All models.\" (Applicability)\n- Procedural references: Airesearch SB No. 49-1045; Grumman Customer Bulletin No. 180; FAA AD 65-9-3. (Document)\n- Compliance interval: \"At intervals not exceeding 250 hours of APU operation or 500 APU starts, whichever occurs first.\" (Compliance)"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrow airworthiness directive focused on a specific mechanical component. It has not expanded beyond its original safety purpose."},"complexity_factors":["Very short document (approximately 150 words)","Only 1 substantive requirement (periodic inspection)","Simple conditional logic (250 hours OR 500 starts, whichever first)","No defined terms section","No cross-references to other legislation","References only external technical documents (service bulletins), not legislative provisions"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety instruction issued by Australia's Civil Aviation Safety Authority (CASA). It applies to all **Gulfstream G.159 series aeroplanes** (a type of aircraft).\n\n**What it requires:**\nOwners and operators must inspect the **APU turbine wheel** at regular intervals. The APU (Auxiliary Power Unit) is a small engine at the back of the aircraft that provides power when the main engines are off.\n\n**How often:**\n- Every **250 hours of APU operation**, **or**\n- Every **500 APU starts**,\n- **Whichever comes first**.\n\n**Why it matters:**\nThis prevents turbine wheel failures that could cause fires or loss of the APU. The directive references three technical documents (service bulletins and a US FAA directive) that detail exactly how to do the inspection.\n\n**Who must comply:**\nAnyone operating or maintaining a Gulfstream G.159 aircraft in Australia."}},"importantCases":[],"_links":{"self":"/api/acts/ad-g159-5-amdt-2-apu-turbine-wheel-inspection","history":"/api/acts/ad-g159-5-amdt-2-apu-turbine-wheel-inspection/history","analysis":"/api/acts/ad-g159-5-amdt-2-apu-turbine-wheel-inspection/analysis","conflicts":"/api/acts/ad-g159-5-amdt-2-apu-turbine-wheel-inspection/conflicts","importantCases":"/api/acts/ad-g159-5-amdt-2-apu-turbine-wheel-inspection/important-cases","documents":"/api/acts/ad-g159-5-amdt-2-apu-turbine-wheel-inspection/documents"}}