{"id":"F2006B10056","name":"AD/G159/12 - Elevator Trim Tab Horn Fitting - Modification","slug":"ad-g159-12-elevator-trim-tab-horn-fitting-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55501,"registerId":"commonwealth-F2006B10056-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/G159/12 - Elevator Trim Tab Horn Fitting - 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/G159/12 Elevator Trim Tab Horn Fitting - Modification 4/71\n\nApplicability: All models.\n\n \n\nDocument: Grumman Customer Bulletin No. 201.\n\n \n\nCompliance: Within 100 hours time in service after 30 April 1971.\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 AD sets out a standalone mandatory modification for all G.159 models and specifies the technical reference and compliance timeframe. The AD text contains no indication that its scope was altered from any prior instrument; it presents the action, applicability and deadline as the operative scope."},"complexity_factors":["Short, narrowly focused directive limited to a single modification (elevator trim tab horn fitting).","Universal applicability across the G.159 fleet but limited technical scope (Applicability: \"All models\").","Compliance deadline specified precisely (100 hours time in service after 30 April 1971), increasing operational scheduling importance.","Technical procedure not included in the AD; it is referenced externally (Grumman Customer Bulletin No. 201), which requires obtaining and following that document.","Regulatory force is clear and leaves little operator discretion, but the AD itself contains no cost or hazard analysis.","Administrative steps (scheduling, parts, maintenance capability) create practical implementation tasks despite the AD's brevity."],"plain_english_summary":"This AD mandates a modification to the elevator trim‑tab horn fitting on all Gulfstream (Grumman) G.159 aeroplanes, to be carried out per Grumman Customer Bulletin No. 201. Owners/operators and maintenance organisations must complete the work within 100 hours time‑in‑service after 30 April 1971; costs (parts, labour, downtime) fall to operators. The directive is a regulator‑required safety action."},"kimi_summary":{"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue airworthiness directive from 1971 addressing a specific mechanical modification. It has not expanded beyond its original purpose of mandating a safety modification to the elevator trim tab horn fitting."},"complexity_factors":["Extremely short document (approximately 150 words)","No defined terms section","No cross-references to other legislation","Simple, unambiguous compliance requirement (single time-based deadline)","No conditional logic or exceptions","Single applicability criterion (all models)","Single referenced technical document"],"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). Think of it like a compulsory recall notice, but for aircraft.\n\n**What it requires:** Owners and operators of **Gulfstream (Grumman) G.159 series aeroplanes** must modify the **elevator trim tab horn fitting** — a mechanical part that helps control the aircraft's pitch (nose up/down movement). The specific work is detailed in \"Grumman Customer Bulletin No. 201.\"\n\n**Who must comply:** Anyone who owns or operates any model of the G.159 aircraft.\n\n**When:** The modification must be completed within **100 hours of flight time** after 30 April 1971.\n\n**Why it matters:** This directive addresses a specific safety defect in the elevator trim system. If left unmodified, the fitting could fail, potentially causing loss of pitch control — a serious flight safety risk. Compliance is legally mandatory; flying without completing this modification would violate civil aviation law."}},"importantCases":[],"_links":{"self":"/api/acts/ad-g159-12-elevator-trim-tab-horn-fitting-modification","history":"/api/acts/ad-g159-12-elevator-trim-tab-horn-fitting-modification/history","analysis":"/api/acts/ad-g159-12-elevator-trim-tab-horn-fitting-modification/analysis","conflicts":"/api/acts/ad-g159-12-elevator-trim-tab-horn-fitting-modification/conflicts","importantCases":"/api/acts/ad-g159-12-elevator-trim-tab-horn-fitting-modification/important-cases","documents":"/api/acts/ad-g159-12-elevator-trim-tab-horn-fitting-modification/documents"}}