{"id":"F2005L03920","name":"AD/RB211/34 - High Pressure Compressor","slug":"ad-rb211-34-high-pressure-compressor","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":39733,"registerId":"commonwealth-F2005L03920-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Rolls Royce Turbine Engines - RB211 Seri","sectionType":"division","heading":"Rolls Royce Turbine Engines - RB211 Series","content":"### Rolls Royce Turbine Engines - RB211 Series\n\n| AD/RB211/34 | High Pressure Compressor | 1/2006 |\n| ----------- | ------------------------ | ------ |\n\n| Applicability: | Rolls-Royce plc Engine Models 524B2-19, 524B-02, 524B3-02, 524C2-19,524B4-02, 524B4-D-02, 524D4-19, 524D4-39, 524B-B-02, 524B2-B-19,524D4-B-19, 524D4-B-39, 524C2-B-19, 524D4X-19, 524D4X-B-19, 524G2-19, 524G3-19, 524H-36, 524H2-19, 535E4-37, 535E4-B-37, 535E4-C-37, 535E4-B-75 and 535C-37 engines installed on Boeing 747, 757, 767, Lockheed L1011, Tristar and Tupolev 204 aeroplanes.                                                                                                                                                 |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Inspect the engine HP compressor interstage weld for evidence of cracks in accordance with the accomplishment instructions and subject to the acceptance criteria of Rolls-Royce Alert Service Bulletin RB211-72-AE359 initial issue or later EASA approved revision.Note: CAA UK G-2005-0028R1 EASA approval No. 2005-6350 dated 3 October 2005 refers.                                                                                                                                                                                       |\n| Compliance:    | Within 30 days after the effective date of this Airworthiness Directive, repetitively at every shop visit where the HP Compressor Stage 1-2 Rotor has been removed from the HP Stage 3 Disc.                                                                                                                                                                                                                                                                                                                                                   |\n|                | This Airworthiness Directive becomes effective on 19 January 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |\n| Background:    | Overhaul inspection of HP Compressor 1 and 2 rotors has identified cracks running in an axial direction in the region of the weld land between the stage 1 and 2 rotor discs. If cracking of the weld land were allowed to propagate for extended periods then it could potentially hazard rotor integrity.This Airworthiness Directive instructs an enhanced shop visit NDT inspection of the HP compressor interstage 1-2 weld for the whole fleet, in order to preclude the risk of a potentially uncontained failure of the HP compressor. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n30 November 2005","sortOrder":0},{"sectionNumber":"AD/RB211/34","sectionType":"part","heading":"AD/RB211/34","content":"## AD/RB211/34","sortOrder":1},{"sectionNumber":"High Pressure Compressor","sectionType":"part","heading":"High Pressure Compressor","content":"## High Pressure Compressor","sortOrder":2},{"sectionNumber":"1/2006","sectionType":"part","heading":"1/2006","content":"## 1/2006","sortOrder":3}],"analysis":{"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD is narrowly limited to requiring inspection of the HP compressor Stage 1–2 interstage weld on specified RB211 engine variants. The directive implements a targeted inspection mandate in response to observed axial cracking; it does not materially expand into other components, broader inspection programmes, or unrelated engine variants. Therefore it has not grown beyond its original, stated purpose of precluding propagation of weld cracks and reducing the risk of an uncontained HP compressor failure."},"complexity_factors":["Long list of applicable engine variants across multiple aircraft types (20+ engine part-number variants listed).","Cross-reference to an external document: Rolls‑Royce Alert Service Bulletin RB211‑72‑AE359 (and any later EASA‑approved revision) — compliance depends on that document’s content.","Fixed time deadline (inspect within 30 days of effective date) combined with a recurring condition tied to a maintenance event (every shop visit when Stage 1‑2 rotor removed from HP Stage 3 disc).","Specified acceptance criteria are not reproduced in the AD but delegated to the service bulletin, creating reliance on an external technical document.","Regulatory approval references (CAA UK G‑2005‑0028R1 and EASA approval No. 2005‑6350) add an extra layer to verify the approved revision.","Technical NDT requirements and repair decisions are inherently specialised, requiring qualified personnel and procedures, but the AD itself is short and procedurally simple."],"plain_english_summary":"**What this instrument does (mechanics)**\n\n- Requires operators and maintenance organisations to inspect the high‑pressure (HP) compressor interstage weld between Stage 1 and Stage 2 rotors on specified Rolls‑Royce RB211 family engines. (See “Requirement” and “Applicability”.)\n- The inspection must follow the procedures and acceptance criteria set out in Rolls‑Royce Alert Service Bulletin RB211‑72‑AE359 (initial issue) or any later revision that has EASA approval. The AD notes an EASA approval reference (No. 2005‑6350) and a UK CAA reference. (See “Requirement”.)\n- Inspections are mandatory within 30 days after the AD’s effective date and then repetitively at every shop visit where the HP Compressor Stage 1‑2 rotor has been removed from the HP Stage 3 disc. (See “Compliance”.)\n\n**Who is affected**\n\n- Aircraft operators, MROs (maintenance, repair and overhaul organisations) and engine shops that operate or service the listed Rolls‑Royce RB211 engine variants installed on Boeing 747/757/767, Lockheed L‑1011 TriStar and Tupolev 204 aeroplanes. (See “Applicability”.)\n- Rolls‑Royce and any other party that supplies the approved Service Bulletin, since the AD mandates use of that document’s instructions and acceptance criteria. (See “Requirement”.)\n\n**Why it matters (stated purpose and tested implications)**\n\n- The stated purpose (from the AD’s Background) is that shop inspections found axial cracks in the weld land between the Stage 1 and 2 rotor discs; if such cracks propagate, there is a risk to rotor integrity and a potential for an uncontained HP compressor failure.\n\n- Mechanically, the AD forces frequent, targeted non‑destructive testing (NDT) of the specified weld area to detect cracks early and require repair or removal from service if acceptance criteria are breached. This changes maintenance practice by making the inspection an explicit, recurring regulatory requirement whenever the rotor assembly is removed as described. (See “Compliance”.)\n\n**Costs, incentives and trade‑offs**\n\n- Who pays: aircraft operators and MROs bear the direct costs — the NDT labour, any additional shop hours, and any repairs or parts required if cracks are found. Using the manufacturer’s service bulletin as the mandated procedure reduces operator choice about inspection technique and acceptance criteria.\n- Incentives: the AD creates an incentive for operators to ensure the prescribed inspection happens at the specified shop events; it also incentivises earlier detection and removal of cracked parts, which can reduce the risk of expensive, catastrophic failures but increase routine maintenance cost and possible parts replacement.\n- Opportunity costs and implementation burden: operators may face additional downtime at shop visits and need access to NDT capability qualified to the service bulletin’s requirements. There is an administrative compliance cost for tracking which engines require inspection and when. The AD ties compliance to a specific maintenance event (rotor removal), which limits frequency to when that event occurs but makes the inspection mandatory at each such occurrence.\n- Detection and regulatory risk: sensitivity of the mandated NDT method affects false positives/negatives. A conservative acceptance criterion reduces safety risk but raises repair/replacement costs; a permissive criterion reduces immediate cost but raises risk of missed cracks.\n\n**Decision‑making and discretion**\n\n- The AD delegates operational implementation to maintenance organisations and the engine manufacturer’s service bulletin. The regulator enforces the AD’s deadlines and recurrence. Operators decide scheduling and pay for the inspections; MROs/engine shops decide how to staff and perform the NDT within the mandated procedures. \n\n**Practical effects on private choice and competition**\n\n- The AD restricts operators’ freedom to choose inspection techniques by mandating the manufacturer’s service bulletin (or later EASA‑approved revision). That concentrates technical compliance around Rolls‑Royce’s specified procedures and any approved successor revisions.\n- Competition among MROs remains possible but each provider must meet the same mandated inspection standard and acceptance criteria.\n\n**Summary statement**\n\nThis AD is a narrowly focused safety mandate requiring standardised, repetitive NDT inspection of the Stage 1–2 HP compressor weld on a list of RB211 engine variants. It shifts inspection and repair costs to operators/MROs, standardises the inspection method through a Rolls‑Royce service bulletin (EASA‑approved), and reduces the risk of an undetected, potentially uncontained HP compressor failure by forcing inspections at defined shop events. (See “Background”, “Requirement”, “Compliance”.)"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive with focused scope. It addresses a specific safety-critical defect in specific engine models and does not appear to have expanded beyond its original safety purpose."},"complexity_factors":["Single, specific technical requirement (inspect one weld location)","Limited applicability (specific engine models on specific aircraft types)","Clear compliance timeline (30 days + repetitive at shop visits)","References external technical document (Rolls-Royce Service Bulletin) rather than embedding all technical details","No nested exceptions or conditional logic — straightforward mandate","Short length (approximately 300 words of substantive content)"],"plain_english_summary":"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:**\nOrders airlines and aircraft operators to inspect a specific part of Rolls-Royce RB211 jet engines — the **High Pressure (HP) Compressor** — for dangerous cracks in a welded area between two rotor discs.\n\n**Who it affects:**\nOperators of Boeing 747, 757, 767, Lockheed L-1011 Tristar, and Tupolev 204 aircraft powered by specific Rolls-Royce RB211 engine models (listed in the document).\n\n**Why it matters:**\nCracks were found in the weld between the first and second stage compressor rotors during overhauls. If these cracks grow unchecked, the compressor rotor could break apart — potentially causing an \"uncontained failure\" where engine parts fly out and damage the aircraft or injure people on the ground. This AD mandates enhanced inspections using special non-destructive testing (NDT) methods to catch cracks before they become catastrophic.\n\n**What operators must do:**\n- Inspect the weld within **30 days** of the directive taking effect (19 January 2006)\n- Repeat the inspection **every time** the engine is in the shop for maintenance and the HP Compressor Stage 1-2 Rotor is removed from the Stage 3 Disc\n- Follow the specific procedures in Rolls-Royce Alert Service Bulletin RB211-72-AE359"}},"importantCases":[],"_links":{"self":"/api/acts/ad-rb211-34-high-pressure-compressor","history":"/api/acts/ad-rb211-34-high-pressure-compressor/history","analysis":"/api/acts/ad-rb211-34-high-pressure-compressor/analysis","conflicts":"/api/acts/ad-rb211-34-high-pressure-compressor/conflicts","importantCases":"/api/acts/ad-rb211-34-high-pressure-compressor/important-cases","documents":"/api/acts/ad-rb211-34-high-pressure-compressor/documents"}}