{"id":"F2008L00388","name":"AD/RB211/37 - Engine - Low Pressure Turbine Shaft","slug":"ad-rb211-37-engine-low-pressure-turbine-shaft","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":119021,"registerId":"commonwealth-F2008L00388-current","compilationNumber":null,"startDate":"2026-04-03","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/RB211/37 | Engine - Low Pressure Turbine Shaft | 3/2008 |\n| ----------- | ----------------------------------- | ------ |\n\n| Applicability: | RB211-22B series engines, all models, all serial numbers; and RB211-524B4-D-02, RB211-524D4-19, RB211-524D4-39, RB211-524D4-B-19, RB211-524D4-B39, RB211-524D4X-19 and RB211-524D4XB-19 engines, all serial numbers.Note 1: These engines are known to be installed on, but not limited to, Boeing 747 series aircraft; and Lockheed L-1011 series aircraft.Note 2: Some RB211-524 series engines and all RB211-535 series Engines, although listed in the referenced Rolls-Royce Non Modification Service Bulletin (NMSB), are not affected by the same unsafe condition and therefore this AD does not apply to those engines. |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. Inspect the LPT shaft in accordance with the accomplishment instructions of Rolls-Royce NMSB 72-AF336 unless previously accomplished.2. Repeat the inspection detailed in Requirement 1 of this AD.3. All LPT shafts inspected according to Rolls Royce NMSB 72-AF336 and found to be cracked must be replaced with serviceable LPT shafts.Note 3: EASA AD 2007-0310R1 dated 8 January 2008 refers. |\n| Compliance: | 1. If on the effective date of this AD, the engine is undergoing a shop visit where the LPT shaft has been completely disassembled to piece-part level in accordance with the appropriate disassembly procedures contained in the Engine Manual and the LPT shaft has not been reprotected with corrosion resistant coating; prior to installing the engine on an aircraft.For all other engines, at the next engine shop visit after the effective date of this AD when the LPT shaft is completely disassembled to piece-part level in accordance with the appropriate disassembly procedures contained in the Engine Manual.2. Following initial inspection of an LPT shaft in accordance with Requirement 1 of this AD, in accordance with the following schedule: |\n\n```html\n

Engine Model

Maximum Time Between Inspections (engine cycles)

RB211-22B Series

3,500

RB211-524B4-D-02

4,000

RB211-524D4-19,
RB211-524D4-39,
RB211-524D4-B-19,
RB211-524D4-B39,
RB211-524D4X-19 and
RB211-524D4X-B-19

Normal shop visit interval

3. Before installing the engine on an aircraft.

This Airworthiness Directive becomes effective on 13 March 2008.

Background:

Several low pressure turbine (LPT) shafts have been found with cracks originating from the rear cooling air holes. The cracks were found at normal component overhaul, by the standard Magnetic Particle Inspection (MPI) technique defined in the associated engine manual. The cracks have been found to initiate from corrosion pits. Propagation of a crack from the rear cooling air holes may result in shaft failure and subsequently in an uncontained Low Pressure Turbine failure. This AD requires the inspection of the affected engines’ LPT shafts and replacement of the shaft, as necessary.

\n```\n\n![](image.001.png) \nCharles Lenarcic \nDelegate of the Civil Aviation Safety Authority\n\n21 January 2008","sortOrder":0},{"sectionNumber":"AD/RB211/37","sectionType":"part","heading":"AD/RB211/37","content":"## AD/RB211/37","sortOrder":1},{"sectionNumber":"Engine - Low Pressure Turbine Shaft","sectionType":"part","heading":"Engine - Low Pressure Turbine Shaft","content":"## Engine - Low Pressure Turbine Shaft","sortOrder":2},{"sectionNumber":"3/2008","sectionType":"part","heading":"3/2008","content":"## 3/2008","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This AD maintains focused scope on the specific unsafe condition (LPT shaft cracking). The applicability notes clarify exclusions to prevent overreach, which is standard practice for aviation safety directives rather than scope creep."},"complexity_factors":["Multiple engine model variants with different compliance intervals (3 distinct scheduling categories)","Conditional compliance timing based on whether engine is already in shop visit at effective date","Cross-reference to external technical document (Rolls-Royce NMSB 72-AF336) for actual inspection procedures","Nested applicability exclusions (Note 2 excludes certain engine models despite being listed in referenced bulletin)","Technical aviation terminology requiring specialized knowledge (LPT shaft, piece-part level, engine cycles, shop visit, MPI)","Dual trigger mechanism for initial compliance (immediate for in-shop engines, deferred to next shop visit for others)"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspections and, if needed, replacement of the Low Pressure Turbine (LPT) shaft on certain Rolls‑Royce RB211 engines after cracks were found starting from corrosion pits around rear cooling holes. It affects operators of aircraft using those engines (notably some Boeing 747s and Lockheed L‑1011s). Compliance with Rolls‑Royce service instructions and repeat inspections/shop replacements is required to prevent uncontained engine failure and to keep aircraft legally operable."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The AD's scope aligns with its stated safety purpose: it identifies affected RB211 models (and excludes other variants), mandates inspections per the Rolls‑Royce NMSB, and requires replacement of cracked LPT shafts. It does not expand or narrow obligations beyond addressing cracking originating at rear cooling air holes as described in the Background."},"complexity_factors":["Targeted applicability covering multiple RB211 submodels with explicit exclusions (Applicability): requires careful model identification.","Normative external reference to Rolls‑Royce NMSB 72‑AF336 and cross‑reference to EASA AD 2007‑0310R1 (Requirement/Background): compliance depends on an external service document.","Model‑specific inspection intervals and a table of engine cycles (Requirement/Compliance): creates operational scheduling complexity for mixed fleets.","Conditional compliance tied to shop‑visit status and disassembly state (Compliance): timing differs if shaft is already disassembled or prior to installation.","Mandatory replacement of any cracked shafts discovered (Requirement): creates immediate parts and labour cost obligations.","Technical inspection method implication (MPI per Background) and need to follow engine manual disassembly procedures: requires specific maintenance capability and recordkeeping."],"plain_english_summary":"This Airworthiness Directive requires operators of specified Rolls‑Royce RB211 engine models to inspect low‑pressure turbine (LPT) shafts in accordance with Rolls‑Royce NMSB 72‑AF336 and to replace any shafts found cracked. Inspections must be repeated on a model‑specific cycle and carried out at the next shop visit or before installation as stated. \n\nIt affects engine owners/operators (who pay for inspections and replacements) and was issued because cracks starting at rear cooling air holes, from corrosion pits, can lead to uncontained LPT failure. Compliance is enforced by the Civil Aviation Safety Authority (effective 13 March 2008)."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-rb211-37-engine-low-pressure-turbine-shaft","history":"/api/acts/ad-rb211-37-engine-low-pressure-turbine-shaft/history","analysis":"/api/acts/ad-rb211-37-engine-low-pressure-turbine-shaft/analysis","conflicts":"/api/acts/ad-rb211-37-engine-low-pressure-turbine-shaft/conflicts","importantCases":"/api/acts/ad-rb211-37-engine-low-pressure-turbine-shaft/important-cases","documents":"/api/acts/ad-rb211-37-engine-low-pressure-turbine-shaft/documents"}}