{"id":"F2006B10083","name":"AD/G159/4 - Main Landing Gear Retract Cylinder Attach Fitting - Inspection and Modification","slug":"ad-g159-4-main-landing-gear-retract-cylinder-attach-fitting-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55544,"registerId":"commonwealth-F2006B10083-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/G159/4 - Main Landing Gear Retract Cylinder Attach Fitting - 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 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/G159/4 Main Landing Gear Retract Cylinder Attach Fitting -\n\nInspection and Modification\n\n\n9/63\n\n \n\nApplicability: S/Nos. 1 to 118.\n\n \n\nDocument: 1. Grumman Customer Bulletin No. 172; or 2. FAA AD 63-21-2.\n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This appears to be the original scope as issued. The directive addresses a specific, narrow safety issue (landing gear fitting integrity) on a limited fleet subset (early serial numbers). There is no evidence of scope creep — the document is a discrete, targeted maintenance requirement without expansion into operational or training matters."},"complexity_factors":["Extremely short document — only 4 substantive lines of regulatory text","No defined terms section; all language is plain technical aviation terminology","No conditional logic or nested exceptions — simple binary applicability (serial numbers 1-118)","Single compliance pathway: follow one of two referenced external documents","No cross-references to other CASA regulations or Civil Aviation Orders","Original issue date (9/63) suggests this is a legacy directive from 1963, predating modern regulatory drafting standards"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It applies to specific Gulfstream G.159 series aeroplanes (serial numbers 1 through 118).\n\n**What it requires:**\nOwners and operators of these aircraft must inspect and modify the **main landing gear retract cylinder attach fitting** — a critical structural component that connects the hydraulic cylinder (which pulls the wheels up into the fuselage) to the airframe.\n\n**Why it matters:**\nThis fitting is under high stress during every landing and retraction cycle. If it cracks or fails, the landing gear could collapse or fail to extend, with potentially catastrophic consequences. The directive mandates compliance with either Grumman's Customer Bulletin No. 172 or the equivalent US Federal Aviation Administration (FAA) directive (AD 63-21-2).\n\n**Who must comply:**\nAnyone operating, maintaining, or owning affected Gulfstream G.159 aircraft in Australian airspace. Non-compliance grounds the aircraft — it cannot legally fly until the work is done."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive, as presented, applies to Gulfstream (Grumman) G.159 series aeroplanes with serial numbers 1 to 118 and requires actions set out in the referenced documents. There is no information in the supplied text indicating a change from an earlier or original scope; the scope is explicit and limited to S/Nos. 1–118. (Applicability: S/Nos. 1 to 118; Document references.)"},"complexity_factors":["Narrow technical scope limited to a single aircraft type and defined serial number range (S/Nos. 1–118). (Applicability: S/Nos. 1 to 118.)","Substantive requirements are delegated to external technical documents rather than spelled out in the directive itself. (Document: Grumman Customer Bulletin No. 172; or FAA AD 63-21-2.)","Technical content (inspection and modification of a landing-gear fitting) requires specialised maintenance skills and parts, creating implementation complexity for operators.","The directive text provided is brief and lacks timing, specific procedures, parts lists, or compliance windows, increasing reliance on referenced documents.","Administrative simplicity in legal form (single directive entry) but practical complexity arises from coordinating maintenance, parts procurement and aircraft downtime."],"plain_english_summary":"This directive mandates inspection and, if required, modification of the main landing‑gear retract‑cylinder attach fitting on Gulfstream (Grumman) G.159 aeroplanes, serial numbers 1–118, using the procedures in Grumman Customer Bulletin No.172 or FAA AD 63‑21‑2. \n\nOwners/operators must arrange and pay for the work—labour, parts and downtime—to address the condition and maintain airworthiness."}},"importantCases":[],"_links":{"self":"/api/acts/ad-g159-4-main-landing-gear-retract-cylinder-attach-fitting-inspection-and-modification","history":"/api/acts/ad-g159-4-main-landing-gear-retract-cylinder-attach-fitting-inspection-and-modification/history","analysis":"/api/acts/ad-g159-4-main-landing-gear-retract-cylinder-attach-fitting-inspection-and-modification/analysis","conflicts":"/api/acts/ad-g159-4-main-landing-gear-retract-cylinder-attach-fitting-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-g159-4-main-landing-gear-retract-cylinder-attach-fitting-inspection-and-modification/important-cases","documents":"/api/acts/ad-g159-4-main-landing-gear-retract-cylinder-attach-fitting-inspection-and-modification/documents"}}