{"id":"F2006B06682","name":"AD/RRT-S/14 - LPT Stage 2 NGV Seal Support","slug":"ad-rrt-s-14-lpt-stage-2-ngv-seal-support","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48692,"registerId":"commonwealth-F2006B06682-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/RRT-S/14 - LPT Stage 2 NGV Seal Support","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)  Rolls Royce Turbine Engines - Spey Series\n\n \n\nAD/RRT-S/14 LPT Stage 2 NGV Seal Support 10/99\n\nApplicability: Rolls Royce Spey 555-15, -15/10, -15H,.-15H/10, -15N, -15N/12, .-15N/20, -15P,\n\n-15P/12, and -15P/20 engines.\n\n \n\nRequirement: Modify affected LPT Stage 2 NGV Seal Supports by incorporating Modification No 6421 in accordance with Rolls Royce Service Bulletin Sp72-1063.\n\n \n\nNote: CAA (UK) AD 007-05-99 also refers.\n\n \n\nCompliance: No later than 30 June 2003.\n\n \n\nThis Airworthiness Directive becomes effective on 7 October 1999.\n\n \n\nBackground: Heavy rubbing can occur between the LP turbine stage 2 nozzle guide vane support ring seal assembly and the LP turbine discs seals. In extreme cases the disc drive arms can be damaged.\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's scope as published matches its stated applicability and required action: it targets listed Spey 555‑15 variants and mandates incorporation of Modification No. 6421 by the compliance date. Nothing in the text indicates a change from its original stated scope; the AD references the Rolls‑Royce service bulletin for technical implementation (Requirement) and notes the related CAA (UK) AD (Note)."},"complexity_factors":["Specific applicability: multiple Rolls‑Royce Spey 555‑15 engine variants are listed (Applicability).","Mandatory technical modification: requires incorporation of Modification No. 6421 per Rolls‑Royce Service Bulletin Sp72‑1063 (Requirement).","External dependency: substantive technical details are contained in the referenced service bulletin rather than in the AD itself (Requirement).","Fixed compliance deadline: work must be completed by 30 June 2003 (Compliance).","Regulatory force: issued as an Airworthiness Directive with an effective date, leaving little administrative discretion (Effective date).","Cross-reference to UK regulator action: CAA (UK) AD 007‑05‑99 is noted (Note)."],"plain_english_summary":"Requires operators of specified Rolls‑Royce Spey 555‑15 series engines to modify the low‑pressure turbine (LPT) stage 2 nozzle guide vane (NGV) seal supports by incorporating Modification No. 6421 in accordance with Rolls‑Royce Service Bulletin Sp72‑1063. It affects owners/operators of the listed engine models, who must complete the mandated work by 30 June 2003 to prevent heavy rubbing between the NGV seal assembly and LPT disc seals that can damage disc drive arms."},"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 a specific engine series. The scope remains tightly focused on the original safety issue without expansion into broader operational or regulatory matters."},"complexity_factors":["Single, specific mechanical modification required","Only 9 engine variants listed in applicability","Clear compliance deadline (single date, no flight hours or cycles)","No nested exceptions or conditional logic","Cross-reference to only one other document (UK CAA AD)","Background explanation provided in plain language","No defined terms section — technical terms are industry standard"],"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 as a \"recall notice\" for aircraft engines, but with legal force.\n\n**What it does:** It requires owners and operators of specific Rolls Royce Spey jet engines to carry out a mechanical modification by a set deadline. Specifically, they must update the \"LPT Stage 2 NGV Seal Support\" — a part in the low-pressure turbine section — by installing a design change called Modification No 6421, following the manufacturer's instructions in Service Bulletin Sp72-1063.\n\n**Who it affects:** Anyone operating aircraft with Rolls Royce Spey 555-15 series engines (including various sub-models like -15H, -15N, -15P and their variants).\n\n**Why it matters:** Without this fix, there's a serious safety risk. The seal support can rub heavily against the turbine disc seals, potentially damaging the disc drive arms. In aviation terms, that's bad news — it could lead to engine failure.\n\n**The deadline:** The modification had to be completed by 30 June 2003.\n\n**Key point:** This isn't optional. Non-compliance means the aircraft cannot legally fly in Australian airspace."}},"importantCases":[],"_links":{"self":"/api/acts/ad-rrt-s-14-lpt-stage-2-ngv-seal-support","history":"/api/acts/ad-rrt-s-14-lpt-stage-2-ngv-seal-support/history","analysis":"/api/acts/ad-rrt-s-14-lpt-stage-2-ngv-seal-support/analysis","conflicts":"/api/acts/ad-rrt-s-14-lpt-stage-2-ngv-seal-support/conflicts","importantCases":"/api/acts/ad-rrt-s-14-lpt-stage-2-ngv-seal-support/important-cases","documents":"/api/acts/ad-rrt-s-14-lpt-stage-2-ngv-seal-support/documents"}}