{"id":"F2006B02293","name":"AD/AL 250/9 - Engine Operating Restrictions to Reduce Torque-Meter Shaftgears Stress","slug":"ad-al-250-9-engine-operating-restrictions-to-reduce-torque-meter-shaftgears-stress","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41523,"registerId":"commonwealth-F2006B02293-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/9 - Engine Operating Restrictions to Reduce Torque-Meter Shaftgears Stress","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)  Allison Turbine Engines - 250 Series\n\n \n\n# AD/AL 250/9 Engine Operating Restrictions to Reduce\n\nTorque-Meter Shaftgears Stress\n\nApplicability: All 250-C18 Series fitted with P/N 6854147 or P/N 6871186 Torque-meter Shaftgears.\n\n \n\nDocument: Allison 250 CSL No. 34.\n\n# 9/69\n\n \n\nCompliance: For para. 1 - at next daily or overnight inspection after 5 Sept.69. For para. 2 - Forthwith.\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":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in specific engine models. It has not expanded beyond its original purpose of preventing torque-meter shaftgear failures through operating restrictions."},"complexity_factors":["Very short document (approximately 150 words of substantive content)","Only 2 defined part numbers for applicability","Simple two-tier compliance structure with clear deadlines","No cross-references to other legislation or regulations beyond the parent Civil Aviation Regulations 1998","Single purpose: impose operating restrictions on specific engine components","No nested exceptions or conditional logic — either your engine has these parts (comply) or it doesn't (ignore)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for aircraft engines.\n\n**What it does:**\nThis directive imposes **operating restrictions on specific Allison 250-C18 turbine engines** to prevent mechanical failure. The engines affected are those fitted with particular torque-meter shaftgears (part numbers 6854147 or 6871186). These components measure engine power output, and this AD was issued because those specific parts were experiencing excessive stress that could lead to dangerous failures.\n\n**Who it affects:**\n- **Aircraft operators** flying planes with Allison 250-C18 engines containing the specified torque-meter shaftgears\n- **Maintenance crews** responsible for inspecting these engines\n- **Pilots** who must follow the new operating restrictions\n\n**What must be done:**\n- **Paragraph 1:** By the next daily or overnight inspection after 5 September 1969, operators must implement certain restrictions (the specific restrictions aren't fully detailed in this excerpt, but typically involve power limits or operational procedures)\n- **Paragraph 2:** \"Forthwith\" — meaning immediately, with no delay\n\n**Why it matters:**\nAirworthiness Directives are **legally binding safety commands**. Ignoring them means an aircraft cannot legally fly. This particular AD addresses a critical safety issue: if the torque-meter shaftgear fails in flight, the pilot could lose power indication or suffer engine damage, potentially leading to catastrophic failure. The 1969 date indicates this is a historical directive, but it remains part of the regulatory record for any aircraft still operating with these vintage engines."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The schedule entry itself is a focused airworthiness directive applying to Allison 250-C18 engines fitted with the two listed torque‑meter shaftgear part numbers. The text does not state or imply any change in the instrument's scope from an earlier or original intent; it specifies applicability, references the manufacturer CSL for details, and sets compliance timing. No evidence in the entry indicates an expansion or narrowing of scope relative to the directive as presented."},"complexity_factors":["Cross-reference to an external manufacturer document (Allison 250 CSL No. 34) for substantive technical instructions rather than containing them in the schedule entry.","Two separate compliance timings (next daily/overnight inspection after a historical date; immediate/forthwith), which create different operational urgencies.","Limited textual detail in the schedule entry about the actual operating restrictions or corrective actions (necessitates retrieval and interpretation of the CSL).","Part‑number specificity (P/N 6854147 and P/N 6871186) requires accurate asset identification by operators and maintenance staff.","Regulatory legal framing under Part 39 creates mandatory effect, reducing discretionary options for operators once applicability is established."],"plain_english_summary":"This is a Part 39 airworthiness directive entry from CASA affecting Allison 250‑C18 engines fitted with torque‑meter shaftgears P/N 6854147 or 6871186. It mandates following the operating restrictions in manufacturer Allison 250 CSL No. 34 to reduce shaftgear stress, with some actions due at the next daily/overnight inspection after 5 Sept 1969 and others required forthwith. Operators bear the compliance costs and must obtain and apply the CSL."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-9-engine-operating-restrictions-to-reduce-torque-meter-shaftgears-stress","history":"/api/acts/ad-al-250-9-engine-operating-restrictions-to-reduce-torque-meter-shaftgears-stress/history","analysis":"/api/acts/ad-al-250-9-engine-operating-restrictions-to-reduce-torque-meter-shaftgears-stress/analysis","conflicts":"/api/acts/ad-al-250-9-engine-operating-restrictions-to-reduce-torque-meter-shaftgears-stress/conflicts","importantCases":"/api/acts/ad-al-250-9-engine-operating-restrictions-to-reduce-torque-meter-shaftgears-stress/important-cases","documents":"/api/acts/ad-al-250-9-engine-operating-restrictions-to-reduce-torque-meter-shaftgears-stress/documents"}}