{"id":"F2006B06555","name":"AD/RB211/24 Amdt 1 - HP Turbine Disc - Inspection","slug":"ad-rb211-24-amdt-1-hp-turbine-disc-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48288,"registerId":"commonwealth-F2006B06555-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/RB211/24 Amdt 1 - HP Turbine Disc - Inspection","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)  \nRolls Royce Turbine Engines \\- RB211 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/RB211/24 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/RB211/24\n\nAmdt 1\n\n  \nHP Turbine Disc \\- Inspection 3/2001\n\nApplicability: RB211-535 engines as detailed in Rolls Royce Service Bulletin RB.211-72-C817 Revision 2.\n\nRequirement: Inspect high pressure turbine (HPT) discs in accordance with Rolls Royce Service Bulletin RB.211-72-C817 Revision 2.\n\nNote: UK CAA AD 003-12-99 refers.\n\nCompliance: As detailed in the requirement document.\n\nThis amendment becomes effective on 22 March 2001.\n\nBackground: This Directive was raised to mandate a mid life eddy current inspection of suspect HP turbine discs to detect possible machining faults in the disc air cooling holes. This amendment reflects the manufacturer’s latest revision to the Requirement document. The revision, in part, reduces the compliance time for inspection and increases the number of discs affected to all discs manufactured between 1989 and 1999. The revision also responds to evidence of disc cooling air holes having been damaged by inappropriate cleaning during overhaul.\n\nThe original issue of this Airworthiness Directive became effective on 10 August 2000.\n\n![Signature of Eugene Paul Holzapfel Delegate of the Civil Aviation Safety Authority](image.003.png)  \n\nEugene Paul Holzapfel\n\nDelegate of the Civil Aviation Safety Authority 9 February 2001\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 21 February 2001.","sortOrder":0}],"analysis":{"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"},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"Yes. This amendment broadened and accelerated the original requirement. Compared with the original AD issued on 10 August 2000, the manufacturer’s Revision 2 (adopted by this amendment) reduced the allowable time before inspection and increased the population of affected discs to include all discs manufactured between 1989 and 1999. The revision also explicitly responds to evidence of damage caused by inappropriate overhaul cleaning, which expands the causal scope addressed by the directive (from alleged machining faults alone to include damage from overhaul practices). These changes increase the number of engines/operators required to act and shorten the window for compliance, thereby enlarging the practical scope and short‑term cost impact of the directive."},"complexity_factors":["Short, single‑issue AD focused on one component (HPT disc) and one engine family (RB211‑535)","Requires compliance with a single external technical document: Rolls‑Royce Service Bulletin RB.211‑72‑C817 Revision 2","One clear applicability criterion (discs manufactured 1989–1999) after amendment","Minimal conditional logic and no nested exceptions within the AD itself","A single cross‑reference to a related UK CAA AD (003‑12‑99)","References a single regulatory basis (CAR 1998 subregulation 39.1(1))"],"plain_english_summary":"**What this instrument does (mechanics)\n\n- This is an Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) that requires inspection of high‑pressure turbine (HPT) discs on Rolls‑Royce RB211‑535 engines. (See the \"Applicability\" and \"Requirement\" headings.)\n\n- The inspections must be carried out in accordance with Rolls‑Royce Service Bulletin RB.211‑72‑C817 Revision 2. (See \"Requirement\" and \"Compliance\".)\n\n- The AD is mandatory under the Civil Aviation Regulations: the CASA delegate revoked the previous AD and replaced it with this amended AD, which takes effect on the stated date. (See opening paragraph and \"This amendment becomes effective on 22 March 2001.\")\n\n**Who is affected\n\n- Aircraft operators and maintenance organisations running or servicing aircraft powered by RB211‑535 engines containing the HPT discs identified in the service bulletin. (See \"Applicability\".)\n\n- Specifically, the amendment expands the set of affected discs to include all discs manufactured between 1989 and 1999. (See \"Background\".)\n\n**What operators must do and who decides\n\n- Operators must arrange and pay for the required mid‑life eddy‑current inspections of the HPT discs, and carry out any subsequent corrective action (repair or replacement) if faults are found. The inspection procedure and timing are those specified in Rolls‑Royce Service Bulletin RB.211‑72‑C817 Revision 2. (See \"Requirement\" and \"Compliance\".)\n\n- CASA (the delegate who signed the AD) makes the regulatory decision to require the inspection; Rolls‑Royce (the manufacturer) supplied the technical inspection procedure in the service bulletin. Operators and maintenance organisations decide how they schedule and perform the inspections to meet the compliance timing.\n\n**Why CASA issued the amendment (stated reason and mechanical effects)\n\n- The AD and this amendment were issued to detect possible machining faults in the discs' air‑cooling holes and to respond to evidence that some cooling holes had been damaged by inappropriate cleaning during overhaul. The manufacturer revised the service bulletin to (a) reduce the time allowed before inspection, and (b) increase the number of discs covered to those made 1989–1999. (See \"Background\".)\n\n**Practical consequences, costs and incentives (mechanical trade‑offs)\n\n- Who pays: Operators and their maintenance providers bear inspection costs, labour and any repair or disc replacement costs, plus aircraft downtime while inspections/repairs are done.\n\n- Behaviour changes forced by the AD: scheduling mid‑life eddy‑current inspections earlier than previously planned; maintenance shops may adopt different cleaning/overhaul practices to avoid damaging cooling holes; increased parts demand if more discs require repair or replacement.\n\n- Implementation risks and constraints: limited MRO (maintenance, repair and overhaul) capacity could increase aircraft downtime; availability of spare discs could affect how quickly defects are corrected; eddy‑current inspections have detection limits (risk of false positives or undetected defects) which affect follow‑on decisions.\n\n- Incentive effects: operators have a clear financial incentive to comply to avoid in‑service failure and regulatory sanctions; manufacturers and overhaul organisations have incentives to refine cleaning and overhaul procedures to reduce future rework.\n\n- Concentration of costs and benefits: a relatively small set of operators (those with RB211‑535 engines and 1989–1999 discs) face concentrated compliance costs; the safety benefit (reduced risk of disc failure) is dispersed among passengers, crew and the broader flying public.\n\n**How to comply in practice\n\n- Follow the inspection steps, intervals and corrective actions exactly as set out in Rolls‑Royce Service Bulletin RB.211‑72‑C817 Revision 2; meet the reduced compliance time required by the amendment; retain records to demonstrate compliance.\n\n**Cross‑references and notes\n\n- The AD notes the related UK CAA AD (003‑12‑99), which is referenced as related material. (See Note.)"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This amendment stays true to the original purpose of ensuring HP turbine disc safety. The changes expand coverage (more discs affected) and tighten timelines, but do not introduce new unrelated requirements or drift from the core safety objective."},"complexity_factors":["Short, single-purpose document (1 page)","Only 4 defined structural sections (Applicability, Requirement, Compliance, Background)","Minimal cross-referencing — only refers to one Service Bulletin and one related UK directive","No nested exceptions or conditional logic chains","Technical but straightforward: mandates a specific inspection method on specific engine parts","Single compliance pathway — no alternative methods or exemptions mentioned"],"plain_english_summary":"This AD requires operators of Rolls‑Royce RB211‑535 engines to perform eddy‑current inspections of high‑pressure turbine discs per Rolls‑Royce Service Bulletin RB.211‑72‑C817 Rev 2. It’s mandatory for airlines and maintenance organisations to detect manufacturing or cleaning‑related damage that could lead to catastrophic disc failure. The amendment expands the population of discs to those manufactured 1989–1999, shortens compliance times, and adds concern about improper cleaning damage during overhauls."}},"importantCases":[],"_links":{"self":"/api/acts/ad-rb211-24-amdt-1-hp-turbine-disc-inspection","history":"/api/acts/ad-rb211-24-amdt-1-hp-turbine-disc-inspection/history","analysis":"/api/acts/ad-rb211-24-amdt-1-hp-turbine-disc-inspection/analysis","conflicts":"/api/acts/ad-rb211-24-amdt-1-hp-turbine-disc-inspection/conflicts","importantCases":"/api/acts/ad-rb211-24-amdt-1-hp-turbine-disc-inspection/important-cases","documents":"/api/acts/ad-rb211-24-amdt-1-hp-turbine-disc-inspection/documents"}}