{"id":"F2006B02454","name":"AD/ARRIEL/7 Amdt 1 - Module 5 Intermediate Pinion","slug":"ad-arriel-7-amdt-1-module-5-intermediate-pinion","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41710,"registerId":"commonwealth-F2006B02454-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/ARRIEL/7 Amdt 1 - Module 5 Intermediate Pinion","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \n![](image.002.png)  \nTurbomeca Turbine Engines \\- Arriel Series\n\nAIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/ARRIEL/7 and issues the following AD under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\nAD/ARRIEL/7\n\nAmdt 1\n\n  \nModule 5 Intermediate Pinion 10/2001\n\nApplicability: Arriel 1A, 1A1, 1B, 1D and 1D1 engines.\n\nRequirement: 1. Arriel 1B, 1D, 1D1 engines not incorporating modification TU 232 and Arriel 1A and 1A1 engines incorporating modification TU 13 but not incorporating modification TU 232;\n\nInspect reduction gearbox (module 5) magnetic plug for evidence of contamination, in accordance with Maintenance Manual chapter 72-80-01, pages 104 and 105.\n\n2. Arriel 1A, 1A1 incorporating modification TU 13 but not incorporating modification TU 39 and Arriel 1B engine not incorporating modification TU 39;\n\nReplace the reduction gearbox (module 5).\n\nNote 1: DGAC AD 92-078(B) refers. Note 2: DGAC AD 92-078(B) refers.\n\nCompliance: 1. At intervals not to exceed 8 hours engine time in service or daily, whichever occurs first.\n\n2. Prior to further flight.\n\nThis amendment becomes effective on 4 October 2001.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.003.png)Background: This Directive was originally issued to require repetitive inspection of the reduction gearbox magnetic plug and to remove from service, reduction gearboxes not incorporating a modified intermediate pinion. Unmodified gearboxes are more prone to intermediate pinion gear failure that may result in a possible turbine overspeed.\n\nThis amendment clarifies engine models applicable and amends the compliance intervals to reflect that detailed in the applicable Turbomeca service bulletin and DGAC airworthiness directive.\n\nThe original issue of this Airworthiness Directive became effective on 25 June 1992.\n\n![](image.004.png)  \n\nEugene Paul Holzapfel\n\nDelegate of the Civil Aviation Safety Authority 13 August 2001\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 12 September 2001.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment remains tightly focused on its original purpose — addressing intermediate pinion gear failures in specific Arriel engine models. The amendment merely clarifies which engine variants are affected and adjusts compliance intervals to match manufacturer service bulletins. It does not expand beyond the original safety concern."},"complexity_factors":["Multiple overlapping applicability categories based on engine model AND modification status (TU 13, TU 232, TU 39)","Two distinct compliance actions (inspection vs replacement) with different thresholds","Cross-reference to French aviation authority directive (DGAC AD 92-078(B)) without reproducing its content","Conditional logic: 'incorporating X but not incorporating Y' structure appears twice","Technical aviation terminology requiring specialized knowledge (magnetic plug, reduction gearbox, module 5, turbine overspeed)"],"plain_english_summary":"This AD from CASA revokes and replaces a prior notice to address intermediate pinion gear failure in Turbomeca Arriel 1A/1A1/1B/1D/1D1 reduction gearboxes that can cause turbine overspeed.  \n\nIt requires operators of affected engines to inspect the gearbox magnetic plug every 8 flight hours or daily for metal contamination if TU 232 is not embodied, and mandates gearbox replacement (grounded until done) for certain older engines lacking TU 39."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"The amendment clarifies which Arriel engine models and modification statuses are subject to inspections and aligns compliance intervals with the Turbomeca service bulletin and DGAC AD. The Background states the amendment 'clarifies engine models applicable and amends the compliance intervals' relative to the original 1992 AD, so the scope was refined rather than newly expanded (Background; Requirement; Compliance)."},"complexity_factors":["Multiple engine variants and modification-status conditions that change required action (Applicability; Requirement 1 & 2).","Very short repetitive inspection interval (every 8 engine hours or daily), increasing operational and administrative burden (Compliance 1).","Mandatory replacement before further flight for certain models creates immediate parts and logistic costs (Requirement 2; Compliance 2).","Cross-references to external documents: Maintenance Manual chapter 72-80-01 pages 104–105 and DGAC AD 92-078(B), requiring users to consult other sources to comply (Requirement; Notes 1–2).","Revocation of the prior AD and an amendment that 'clarifies' applicability and aligns intervals with service bulletins—introduces tracing and version-control work for operators and maintainers (Background).","Duplicate notes referencing the same DGAC AD may cause minor confusion (Notes 1 and 2).","Clear delegation of authority to CASA delegate to issue and revoke ADs, but limited operational discretion for addressees—compliance actions are prescriptive (preamble; Requirement; Compliance)."],"plain_english_summary":"This directive requires operators of certain Turbomeca Arriel 1A/1A1/1B/1D/1D1 engines to inspect the reduction-gearbox (module 5) magnetic plug at least every 8 engine hours or daily, and to replace the module 5 gearbox in specified models before further flight. It applies to engines lacking particular factory modifications (TU 232, and in some cases TU 39) to reduce the risk of intermediate pinion failure and potential turbine overspeed; operators must follow the cited Maintenance Manual pages and bear inspection and replacement costs."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-arriel-7-amdt-1-module-5-intermediate-pinion","history":"/api/acts/ad-arriel-7-amdt-1-module-5-intermediate-pinion/history","analysis":"/api/acts/ad-arriel-7-amdt-1-module-5-intermediate-pinion/analysis","conflicts":"/api/acts/ad-arriel-7-amdt-1-module-5-intermediate-pinion/conflicts","importantCases":"/api/acts/ad-arriel-7-amdt-1-module-5-intermediate-pinion/important-cases","documents":"/api/acts/ad-arriel-7-amdt-1-module-5-intermediate-pinion/documents"}}