{"id":"F2006L02501","name":"AD/RB211/36 - High Pressure Turbine Cooling Air Holes","slug":"ad-rb211-36-high-pressure-turbine-cooling-air-holes","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":59707,"registerId":"commonwealth-F2006L02501-current","compilationNumber":null,"startDate":"2026-04-02","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/RB211/36 | High Pressure Turbine Cooling Air Holes | 9/2006 |\n| ----------- | --------------------------------------- | ------ |\n\n| Applicability: | Rolls Royce Models RB211-524-02, 524B2-19, 524B2-39, 524B-02, 524B3-02, 524C2-19, 524B4-02, 524B4-D-02, 524D4-19, 524D4-39, 524D4-B-19, 524D4-B-39, 524D4X-19, 524D4X-B-19, 524B-B-02, 524B2-B-19, 524C2-B-19, 524G2-19, 524G3-19, 524G2-T-19, 524G3-T-19, 524H-36, 524H2-19, 524H-T-36 and524H2-T-19 installed on, but not limited to, Boeing 747, Boeing 767 and Lockheed L-1011 aircraft                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Carry out an Eddy Current Inspection (ECI), as defined in Section 3., Accomplishment instructions of Rolls-Royce NMSB 72-AE969 or later EASA approved revision on the HP turbine discs identified in Sections 1.A.(3) and 1.A.(4) of Rolls-Royce NMSB 72-AE969 or later EASA approved revision.2. Repeat the inspection as detailed in requirement 1of this AD.Note: EASA AD 2006-0180 dated 26 June 2006 refers.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |\n| Compliance:    | 1. In accordance with the following schedule:By whichever is the soonest of the following conditions:a) If the HP turbine disc cycles since new is greater than 2750 cycles on the effective date of this AD, then inspect the disc at next shop visit where the HP turbine blades have been removed from the HP turbine disc.b) If the HP turbine disc cycles since new is greater than 2750 cycles on the effective date of this AD; and- the HP turbine rotor is currently undergoing a shop visit, and- has not yet been reinstalled into the Combustor Outer Case, and- the HP turbine blades have been removed from the HP turbine disc, then the HP turbine disc must be inspected before fitment to an aeroplane.If a HP turbine disc has previously passed inspection to the Eddy Current inspection procedure as defined in Rolls-Royce TSD594-J Overhaul Process Manual Task 70-00-00-200-223 and at a disc life above 2750 cycles since new that meets the criteria detailed in requirement 1 of this AD, then that inspection satisfies the requirements stated in requirement 1 of this AD. |\n\n|             | 2. At every subsequent shop visit where the HP turbine blades have been removed from the HP turbine disc.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |\n| ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n|             | This Airworthiness Directive becomes effective on 31 August 2006.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |\n| Background: | HPT Discs recently inspected in accordance with the Engine Manual have exhibited cracks in the disc rim. The discs have failed to meet the inspection acceptance criteria and have been returned to Rolls-Royce for engineering investigation. This investigation has concluded that the cracks have resulted from scores within the cooling air holes in the disc rim that could have been introduced during new part manufacture or during overhaul of the disc. The engineering investigation has also concluded that if this cracking was undetected then it could result in uncontained disc failure. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n21 July 2006","sortOrder":0},{"sectionNumber":"AD/RB211/36","sectionType":"part","heading":"AD/RB211/36","content":"## AD/RB211/36","sortOrder":1},{"sectionNumber":"High Pressure Turbine Cooling Air Holes","sectionType":"part","heading":"High Pressure Turbine Cooling Air Holes","content":"## High Pressure Turbine Cooling Air Holes","sortOrder":2},{"sectionNumber":"9/2006","sectionType":"part","heading":"9/2006","content":"## 9/2006","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"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a standard single-issue Airworthiness Directive focused on a specific safety-critical defect in a defined set of engine models. The scope remains tightly constrained to the original safety concern (HPT disc cracking) without expansion into broader operational or maintenance requirements."},"complexity_factors":["Multiple conditional compliance pathways based on engine cycle count (2,750 cycles threshold), current maintenance status, and prior inspection history","Cross-reference to external technical documents (Rolls-Royce NMSB 72-AE969 and TSD594-J Overhaul Process Manual) that are not reproduced in the directive itself","Nested logical conditions in compliance section: 'if X and Y and Z, then...' structure with three simultaneous conditions for immediate inspection","Technical aviation terminology requiring domain knowledge (Eddy Current Inspection, shop visit, Combustor Outer Case, cycles since new)","Long list of 22 specific engine model variants in applicability section","Reference to European regulator (EASA AD 2006-0180) creating inter-jurisdictional dependency"],"plain_english_summary":"This Airworthiness Directive mandates Eddy Current Inspections of High Pressure Turbine (HPT) discs in specified Rolls‑Royce RB211 engines used on certain Boeing 747/767 and Lockheed L‑1011 aircraft. It targets cracks found at cooling‑air holes that could lead to catastrophic uncontained disc failure.\n\nOperators and maintenance organisations must inspect affected discs at the next major overhaul (or before return to service if in shop) and at each subsequent overhaul to prevent in‑flight disintegration."},"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":false,"description":"The instrument confines its scope to specified RB211 engine models and to inspection requirements (ECI) tied to clearly stated triggers (cycles and shop-visit conditions). It does not broaden obligations beyond inspection and repeat-inspection rules, while it allows previously conforming inspections under Rolls‑Royce TSD594-J to satisfy the requirement (Applicability; Requirement; Compliance; Compliance note)."},"complexity_factors":["Detailed model-by-model applicability covering many RB211 variants increases administrative filtering for operators (Applicability).","Conditional compliance triggers tied to cycles-since-new thresholds (>2750 cycles) and specific shop visit states create branching timing rules (Compliance: paragraphs a and b).","Mandate references external technical documents — Rolls‑Royce NMSB 72-AE969 (or later EASA-approved revision) for inspection procedure — requiring cross-checking of multiple publications (Requirement).","Acceptance of prior inspections if performed under Rolls‑Royce TSD594-J at disc life above 2750 cycles introduces an alternative compliance path that must be verified (Compliance note).","Inspection technique specified (Eddy Current Inspection) imposes a technical capability requirement on maintenance organisations (Requirement: ECI).","Repeat-inspection obligation at every shop visit where blades are removed implies recurring maintenance costs and operational scheduling impacts (Requirement; Compliance).","Safety rationale (risk of uncontained disc failure from scoring in cooling holes) creates low-tolerance for procedural ambiguity, increasing demand for clear acceptance criteria and record-keeping (Background).","Effective date and immediate applicability (31 August 2006) can compress implementation timelines for operators with affected engines (Effective date)."],"plain_english_summary":"This directive requires operators and maintenance organisations to perform an Eddy Current Inspection (ECI) of High Pressure Turbine (HPT) discs on specified Rolls‑Royce RB211 engine models, and to repeat that inspection at every subsequent shop visit where the HPT blades are removed, following Rolls‑Royce service instructions (Requirement; Compliance). It targets engines meeting certain cycle or in‑shop conditions because scoring in cooling‑air holes has been found to cause cracks that could lead to uncontained disc failure (Background)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-rb211-36-high-pressure-turbine-cooling-air-holes","history":"/api/acts/ad-rb211-36-high-pressure-turbine-cooling-air-holes/history","analysis":"/api/acts/ad-rb211-36-high-pressure-turbine-cooling-air-holes/analysis","conflicts":"/api/acts/ad-rb211-36-high-pressure-turbine-cooling-air-holes/conflicts","importantCases":"/api/acts/ad-rb211-36-high-pressure-turbine-cooling-air-holes/important-cases","documents":"/api/acts/ad-rb211-36-high-pressure-turbine-cooling-air-holes/documents"}}