{"id":"F2005L00221","name":"AD/TAY/5 Amdt 3 - HP Compressor OGV Segment to Outer Seal Spacer Retaining Bolt Release","slug":"ad-tay-5-amdt-3-hp-compressor-ogv-segment-to-outer-seal-spacer-retaining-bolt-release","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":33767,"registerId":"commonwealth-F2005L00221-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Rolls Royce Turbine Engines - Tay Series","sectionType":"division","heading":"Rolls Royce Turbine Engines - Tay Series","content":"### Rolls Royce Turbine Engines - Tay Series\n\n| AD/TAY/5 Amdt 3 | HP Compressor OGV Segment to Outer Seal Spacer Retaining Bolt Release | 3/2005 |\n| --------------- | --------------------------------------------------------------------- | ------ |\n\n| Applicability: | Rolls-Royce Aircraft Engine Models TAY 650-15, 650-15/10 and TAY 651-54 that do not incorporate Rolls Royce Service Bulletin (SB)Tay-72-1498 Revision 1 dated 01 December 2000; orTay 72-1498 Revision 2 dated 31 December 2004.                                                                                                                                                                                                                                                                                             |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Carry out inspection in accordance with Rolls Royce SB Tay-72-1483 Revision 2 dated 20 October 2000.2. Modify the engine in accordance with Rolls Royce SB Tay-72-1498 Revision 2.Note 1: German LBA AD D-2004-365 approved under EASA approval No. 2004-12660 dated 31 December 2004 refers.Note 2: AD D-2004-365 supersedes UK CAA Airworthiness Directives 003-10-2000 and 005-12-99.                                                                                                                                  |\n| Compliance:    | 1. As detailed in the requirement document.2. (a) At the latest by 31 October 2007 for Engine Models Tay 650-15 and Tay 650-15/10.(b) At the latest by 30 September 2012 for Engine Model Tay 651-54.Note 3: Compliance with Requirement 2 constitutes terminating action for Requirement 1 of this AD.                                                                                                                                                                                                                      |\n|                | This Amendment becomes effective on 17 March 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |\n| Background:    | Several incidents of HPC OGV segment to outer seal spacer retaining bolt release have been reported on TAY 650-15 series engines. In extreme cases this has led to cracking of the stage 11-12 spacer. The problem is attributed to the OGV retaining bolts cracking in Low Cycle Fatigue (LCF) at the point where the bolts enter the diffuser case. This is as a result of bending loads imparted by a transient thermal mismatch between the inner seal carrier and the diffuser case flange near Maximum Take Off (MTO). |\n\n|     | The actions specified by this Airworthiness Directive are intended to prevent HPC OGV segment to outer seal spacer retaining bolt release, which can result in an uncontained engine failure and damage to the airplane.The current amendment revises the compliance dates and makes reference to the latest revision of the applicable Service Bulletins.Amendment 2 of this AD became effective on 25 December 2003.Amendment 1 of this AD became effective on 13 June 2002.The original issue of this AD became effective on 15 June 2000. |\n| --- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n4 February 2005","sortOrder":0},{"sectionNumber":"AD/TAY/5 Amdt 3","sectionType":"part","heading":"AD/TAY/5 Amdt 3","content":"## AD/TAY/5 Amdt 3","sortOrder":1},{"sectionNumber":"HP Compressor OGV Segment to Outer Seal ","sectionType":"part","heading":"HP Compressor OGV Segment to Outer Seal Spacer Retaining Bolt Release","content":"## HP Compressor OGV Segment to Outer Seal Spacer Retaining Bolt Release","sortOrder":2},{"sectionNumber":"3/2005","sectionType":"part","heading":"3/2005","content":"## 3/2005","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This amendment does not introduce new types of action beyond inspection and modification but does change the instrument's operational scope by revising compliance dates and by referencing later revisions of the Rolls‑Royce service bulletins. In practical terms that affects when operators must complete the terminating modification and which SB revision procedures they must follow. The fleet of affected engines and the substantive technical remedy remain the same; the amendment mainly adjusts timing and the exact SB revisions to be used."},"complexity_factors":["Two distinct mandatory actions (inspection per SB Tay‑72‑1483 Rev 2; modification per SB Tay‑72‑1498 Rev 2)","Different compliance deadlines for different engine models (Tay 650‑15/650‑15/10 vs Tay 651‑54)","Terminating action relationship (Requirement 2 terminates Requirement 1) adds conditional logic","Multiple cross‑references to external documents (two Rolls‑Royce SBs, German LBA AD, and EASA approval)","Applicability excludes engines that have already incorporated specific SB revisions (requires checking maintenance records)","Notes and prior amendments referenced (Amendment history/previous AD versions)"],"plain_english_summary":"**What this instrument does (mechanically)\n\n- Applies to Rolls‑Royce Tay turbofan engines: models TAY 650‑15, TAY 650‑15/10 and TAY 651‑54, except those that have already had the specific Rolls‑Royce service bulletin (SB Tay‑72‑1498) incorporated (Applicability). \n\n- Requires two actions for affected engines:\n  - Requirement 1: carry out an inspection in accordance with Rolls‑Royce Service Bulletin Tay‑72‑1483 Revision 2 (an inspection procedure) (Requirement 1). \n  - Requirement 2: modify the engine in accordance with Rolls‑Royce Service Bulletin Tay‑72‑1498 Revision 2 (a modification that changes hardware or installation) (Requirement 2). Note: completing Requirement 2 ends the need to keep doing Requirement 1 (the modification is “terminating action” for the inspection) (Compliance note 3).\n\n- Sets deadlines for the modification (Requirement 2):\n  - For Tay 650‑15 and Tay 650‑15/10 — no later than 31 October 2007 (Compliance 2(a)).\n  - For Tay 651‑54 — no later than 30 September 2012 (Compliance 2(b)).\n\n- Becomes effective 17 March 2005.\n\nWhy the regulator put this in place (stated purpose)\n\n- The AD explains that several incidents occurred where high‑pressure compressor (HPC) outlet guide vane (OGV) segment retaining bolts (that hold the OGV segment to an outer seal spacer) loosened or released. In severe cases stage spacer cracking and the potential for an uncontained engine failure were observed. The reported failure mode was bolt cracking from low cycle fatigue (LCF) caused by bending stresses produced by transient thermal mismatch near maximum take‑off conditions (Background).\n\n- The stated intent of the AD is to prevent retaining‑bolt release and the resulting risk of engine damage or uncontained failure.\n\nWho is affected and who decides\n\n- Operators and owners of the specified Tay engines who have not already incorporated SB Tay‑72‑1498 (see Applicability) must arrange inspections and, by the deadlines, the mandated modifications. Maintenance organisations or Rolls‑Royce authorised repair shops will typically perform the work according to the cited Rolls‑Royce SBs.\n\n- The Civil Aviation Safety Authority (CASA) delegate issued the AD (signature block). The required work must follow the Rolls‑Royce SB instructions referenced in the AD.\n\nPractical effects, costs and trade‑offs (mechanisms, not judgements)\n\n- Compliance cost and downtime: operators must pay for inspections and for the specified modification work (labour, parts, and shop time). The modification replaces or alters components so that the LCF/bending load condition is mitigated; once modified, regular inspections required by Requirement 1 are no longer required (terminating action) (Compliance note 3).\n\n- Timing trade‑off: the AD imposes model‑specific deadlines for completing the modification. Operators must plan maintenance schedules and part availability to meet those dates. If an operator delays modification, it must continue the inspection regime until the modification is done.\n\n- Incentives: operators must comply to remain airworthy. Maintenance and overhaul providers have a demand signal (work to carry out inspections and modifications). The OEM (Rolls‑Royce) supplies the technical instructions (SBs) referenced; following those SBs is the mechanism by which the regulator enforces a uniform technical solution.\n\n- Implementation risks and constraints: the AD’s effectiveness depends on correct execution of the SB procedures, parts availability, and workshop capacity. The AD cross‑references two different SBs (one for inspection, one for modification) and requires a specific revision of each; that creates dependence on the content and clarity of those SBs.\n\n- Distribution of costs/benefits: the safety benefit (reduced risk of bolt release and uncontained failure) accrues broadly to operators, airframes, crew and passengers; the direct costs of inspection and modification are borne by engine owners/operators. Maintenance providers capture the revenue for performing the work.\n\nNotes and cross‑references\n\n- The AD requires the inspection per SB Tay‑72‑1483 Revision 2 and the modification per SB Tay‑72‑1498 Revision 2 (Requirement). It also notes that the German LBA AD D‑2004‑365 and EASA approval relate to the same issue (Notes 1 and 2).\n\n- This Amendment revises compliance dates and refers to the latest revisions of the service bulletins compared with earlier versions of the AD (Summary/Background).\n\nBottom line: If you operate one of the listed Tay engines and have not already done the SB Tay‑72‑1498 modification, you must have the engine inspected per SB Tay‑72‑1483 Rev 2 and then complete the SB Tay‑72‑1498 Rev 2 modification by the model‑specific dates. The modification removes the need for further inspections under Requirement 1."},"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is Amendment 3 of an existing Airworthiness Directive. The amendments have remained focused on the original safety issue (bolt release in HPC OGV segments). The changes from previous versions are limited to: (1) revised compliance dates, and (2) updated references to the latest service bulletin revisions. The scope has not expanded beyond the original safety concern."},"complexity_factors":["Technical aviation terminology throughout (HPC, OGV, LCF, MTO, SB)","Multiple cross-references to external Rolls-Royce Service Bulletins (SB Tay-72-1483 and SB Tay-72-1498)","Conditional applicability based on whether specific service bulletin revisions have been incorporated","Staggered compliance dates based on engine model variants","Reference to foreign regulatory documents (German LBA AD D-2004-365, UK CAA Airworthiness Directives)","Terminating action clause (compliance with Requirement 2 ends Requirement 1 obligations)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It applies to specific **Rolls-Royce Tay jet engines** used in aircraft.\n\n**What it does:**\n- **Requires inspections** of a specific engine component: the bolts that hold the High Pressure Compressor (HPC) Outlet Guide Vane (OGV) segments to the outer seal spacer.\n- **Requires modifications** to fix a design flaw where these bolts can crack and break due to metal fatigue caused by heat expansion differences during take-off.\n\n**Why it matters:**\n- Broken bolts can cause **uncontained engine failure** — where engine parts break off and potentially damage the aircraft or injure passengers.\n- Several incidents have already occurred where bolts released, and in severe cases, caused cracking in other engine parts.\n\n**Who must comply:**\n- Owners/operators of aircraft with **Tay 650-15, 650-15/10, or 651-54** engines that haven't already been modified under specific Rolls-Royce service bulletins.\n\n**Deadlines:**\n- **Tay 650-15 and 650-15/10 models:** By 31 October 2007\n- **Tay 651-54 model:** By 30 September 2012\n\n**Key point:** Once you complete the modification (Requirement 2), you don't need to keep doing the inspections (Requirement 1)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tay-5-amdt-3-hp-compressor-ogv-segment-to-outer-seal-spacer-retaining-bolt-release","history":"/api/acts/ad-tay-5-amdt-3-hp-compressor-ogv-segment-to-outer-seal-spacer-retaining-bolt-release/history","analysis":"/api/acts/ad-tay-5-amdt-3-hp-compressor-ogv-segment-to-outer-seal-spacer-retaining-bolt-release/analysis","conflicts":"/api/acts/ad-tay-5-amdt-3-hp-compressor-ogv-segment-to-outer-seal-spacer-retaining-bolt-release/conflicts","importantCases":"/api/acts/ad-tay-5-amdt-3-hp-compressor-ogv-segment-to-outer-seal-spacer-retaining-bolt-release/important-cases","documents":"/api/acts/ad-tay-5-amdt-3-hp-compressor-ogv-segment-to-outer-seal-spacer-retaining-bolt-release/documents"}}