{"id":"F2006B02237","name":"AD/AL 250/14 - Compressor Wheels, Glass Bead Peening","slug":"ad-al-250-14-compressor-wheels-glass-bead-peening","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41467,"registerId":"commonwealth-F2006B02237-current","compilationNumber":null,"startDate":"2026-04-01","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/14 - Compressor Wheels, Glass Bead Peening","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-description: CASA Airworthiness Directive\nmeta-generator: Aspose.Words for .NET 22.10.0\nmeta-keywords: Issue 11/1970,Turbine engines,Allison Turbine Engines - 250 Series,Compressor Wheels, Glass Bead Peening,14\ntitle: Airworthiness Directive - AD/AL 250/14 - Compressor Wheels, Glass Bead Peening\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)  Allison Turbine Engines - 250 Series\n\n \n\nAD/AL 250/14 Compressor Wheels, Glass Bead Peening 11/70\n\nApplicability: All Compressor Assemblies with S/Nos. prior to CAC 21525B fitted to 250-C18 series engines and all Assemblies with S/Nos. prior to CAC 21773B fitted to 250- C18A engines.\n\n \n\nDocument: Allison 250 CEB 106.\n\n \n\nCompliance: Before installation in an aircraft following next overhaul completed after 1 December 1970.\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":1415},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive maintains its original narrow technical scope as a specific preventive maintenance requirement for identified compressor wheel serial numbers, with no expansion into broader operational or regulatory areas."},"complexity_factors":["Single, specific technical requirement (glass bead peening)","Narrow applicability limited to two engine variants and specific serial number cutoffs (prior to CAC 21525B and CAC 21773B)","One external document reference (Allison 250 CEB 106) without incorporation of its contents","Simple conditional compliance trigger tied to overhaul schedule rather than calendar date"],"plain_english_summary":"**What this does:** This is a mandatory safety instruction (called an Airworthiness Directive) that requires a specific surface treatment—**glass bead peening** (a process that blasts tiny glass beads at metal to strengthen it and prevent cracks)—to be applied to compressor wheels in certain aircraft engines.\n\n**Who it affects:** Owners and operators of aircraft fitted with **Allison 250-C18 or 250-C18A turbine engines** that have compressor assemblies with serial numbers below CAC 21525B (for C18 models) or CAC 21773B (for C18A models).\n\n**What must be done:** Before reinstalling these compressor wheels into an aircraft after their next scheduled overhaul (if that overhaul happens after 1 December 1970), the wheels must undergo glass bead peening treatment according to the manufacturer's instructions in **Allison 250 CEB 106**. This prevents metal fatigue and potential engine failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-14-compressor-wheels-glass-bead-peening","history":"/api/acts/ad-al-250-14-compressor-wheels-glass-bead-peening/history","analysis":"/api/acts/ad-al-250-14-compressor-wheels-glass-bead-peening/analysis","conflicts":"/api/acts/ad-al-250-14-compressor-wheels-glass-bead-peening/conflicts","importantCases":"/api/acts/ad-al-250-14-compressor-wheels-glass-bead-peening/important-cases","documents":"/api/acts/ad-al-250-14-compressor-wheels-glass-bead-peening/documents"}}