{"id":"F2006B09259","name":"AD/DHE/1 - Accessory Drive Shaft - Modification to Provide Weak Neck","slug":"ad-dhe-1-accessory-drive-shaft-modification-to-provide-weak-neck","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53231,"registerId":"commonwealth-F2006B09259-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHE/1 - Accessory Drive Shaft - Modification to Provide Weak Neck","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 - 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  De Havilland Piston Engines\n\n \n\nAD/DHE/1 Accessory Drive Shaft - Modification NK\n\nto Provide Weak Neck\n\nApplicability: Gipsy Six II and Gipsy Queen II. Document:  1. DH Mod. G1018; or\n\n2. DH Mod. G1079; or 3. ANO 106.1.7.0.1.1.\n\nCompliance: Before installation in an aircraft.\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":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1859},"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"The directive remains tightly focused on its original technical purpose: mandating a specific safety modification to the accessory drive shaft of two engine models. There is no evidence of scope expansion beyond this narrow mechanical requirement."},"complexity_factors":["Single, unambiguous operational requirement (modify shaft before installation)","Limited applicability to only two specific engine models","No defined terms section or legislative cross-references","Simple alternative compliance pathways (three permissible technical standards with no hierarchy)","No conditional logic, exceptions, or sunset clauses"],"plain_english_summary":"This Airworthiness Directive is a mandatory safety order applying to two specific vintage aircraft engine models: the De Havilland **Gipsy Six II** and **Gipsy Queen II**.\n\n**What it requires**\nBefore either engine can be lawfully installed in an aircraft, the **accessory drive shaft** must be modified to create a **\"weak neck\"** — a deliberately engineered weak point that acts like a mechanical fuse. If the engine seizes or encounters extreme resistance, this neck is designed to shear or break first, preventing catastrophic damage to the engine casing and other critical components.\n\n**How to comply**\nThe modification must be performed exactly according to one of three approved technical specifications:\n*   DH Modification G1018\n*   DH Modification G1079\n*   ANO 106.1.7.0.1.1\n\n**Who is affected**\nAircraft owners, maintenance engineers, and repair stations handling these specific vintage De Havilland engines, typically found in historic aircraft such as the Dove, Heron, or Rapide."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhe-1-accessory-drive-shaft-modification-to-provide-weak-neck","history":"/api/acts/ad-dhe-1-accessory-drive-shaft-modification-to-provide-weak-neck/history","analysis":"/api/acts/ad-dhe-1-accessory-drive-shaft-modification-to-provide-weak-neck/analysis","conflicts":"/api/acts/ad-dhe-1-accessory-drive-shaft-modification-to-provide-weak-neck/conflicts","importantCases":"/api/acts/ad-dhe-1-accessory-drive-shaft-modification-to-provide-weak-neck/important-cases","documents":"/api/acts/ad-dhe-1-accessory-drive-shaft-modification-to-provide-weak-neck/documents"}}