{"id":"F2006B08472","name":"AD/CF6/29 Amdt 1 - High Pressure Turbine - Stage 1 Disc Rim Bolt Holes and Stage 2 Disc Rim and Inner Bolt Holes","slug":"ad-cf6-29-amdt-1-high-pressure-turbine-stage-1-disc-rim-bolt-holes-and-stage-2-disc-rim-and-inner-bo","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51135,"registerId":"commonwealth-F2006B08472-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CF6/29 Amdt 1 - High Pressure Turbine - Stage 1 Disc Rim Bolt Holes and Stage 2 Disc Rim and Inner Bolt Holes","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)  \nGeneral Electric Turbine Engines \\- CF6 Series\n\nAD/CF6/29\n\nAmdt 1\n\n  \n\nHigh Pressure Turbine - Stage 1 Disc Rim Bolt Holes and Stage 2 Disc Rim and Inner Bolt Holes\n\n  \n13/94\n\nApplicability: General Electric CF6-45/50/-6 series engines.\n\nRequirement: Action in accordance with the technical requirements of the September 1994 corrected issue of FAA AD 94-09-18.\n\nNote: General Electric Service Bulletins 72-1002, 1003, 1057 and 1059 refer.\n\nCompliance: As specified in the FAA AD with a revised effective date of 8 December 1994.\n\nBackground: The requirement arises from an uncontained high pressure turbine disc failure which resulted in an aborted take-off. This amendment incorporates changes to two sections but does not constitute a major change in the thrust of the overall AD document.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The amendment incorporates changes to two sections of the earlier AD document but, according to the text, does not constitute a major change in the overall thrust or scope of the AD. The instrument continues to require compliance with the technical requirements of FAA AD 94-09-18 and references the same GE service bulletins, preserving the original applicability to GE CF6-45/50/-6 series engines. (Background, Requirement, Applicability)"},"complexity_factors":["Cross-reference to an external technical document (FAA AD 94-09-18) for the substantive technical requirements","Reference to multiple manufacturer service bulletins (GE SBs 72-1002, 1003, 1057, 1059) for procedural detail","Operational logistics required for inspections/repairs (engine downtime, part procurement, maintenance capacity)","Legal straightforwardness of adoption (prescriptive compliance required) reduces interpretive complexity","Limited information in the instrument itself about the technical steps increases practical reliance on external technical documents"],"plain_english_summary":"What this instrument does\n\n- Requires owners/operators/maintainers of General Electric CF6-45/50/-6 series engines to carry out the specific technical actions set out in the September 1994 corrected issue of FAA Airworthiness Directive (AD) 94-09-18. (Requirement)\n- It refers operators and maintainers to related General Electric Service Bulletins 72-1002, 72-1003, 72-1057 and 72-1059 for detail. (Note)\n- The compliance schedule follows the FAA AD and takes effect with a revised date of 8 December 1994. (Compliance)\n\nWhy the rule exists (official rationale)\n\n- The AD is presented as a response to an uncontained high pressure turbine (HPT) disc failure that caused an aborted take‑off. The amendment updates two sections of the earlier directive but, according to the text, does not change the overall intent of the original AD. (Background)\n\nWho it affects and who decides\n\n- Affected parties: aircraft operators and maintenance organisations that operate aircraft fitted with GE CF6-45/50/-6 engines. (Applicability)\n- Decision authority: the Civil Aviation Safety Authority (CASA) issues the AD by incorporating the FAA AD’s technical requirements; the FAA AD defines the concrete inspection/repair actions and timings. (Requirement, Compliance)\n\nPractical mechanics, incentives and costs\n\n- Mechanical effect: operators must perform the inspection, repair or replacement actions that the FAA AD prescribes for the stage 1 disc rim bolt holes and the stage 2 disc rim and inner bolt holes. The AD points operators to GE service bulletins for the detailed procedures. (Requirement, Note)\n- Who pays: operators bear the direct costs of inspections, maintenance actions, part replacement and any operational downtime required to comply. (Requirement, Compliance)\n- Compliance burden and implementation risk: complying requires technical maintenance capacity, scheduling of engine downtime, possible parts procurement and record-keeping to evidence compliance; that burden varies by operator size and fleet logistics. (Requirement, Note, Compliance)\n- Regulatory discretion: the AD is prescriptive — CASA requires compliance with the FAA AD’s technical content and timing, so there is limited regulatory discretion at the operator level beyond scheduling how and when to carry out the mandated actions. (Requirement, Compliance)\n\nTrade-offs and potential consequences (mechanisms, not value judgments)\n\n- The instrument trades operator costs (inspections, repairs, downtime) for the safety objective stated in the background (prevention of uncontained disc failures). (Background, Requirement)\n- There may be substitution effects for operators: choices about when to schedule maintenance, whether to use spare engines, or whether to retire/replace affected engines sooner than planned. (Applicability, Requirement)\n- Concentration of costs and benefits: the compliance costs fall directly on operators and maintenance providers; the safety benefit, as stated, accrues to aircraft operations generally. (Applicability, Background)\n\nScope change from prior wording\n\n- The amendment modifies two sections of the prior AD document but, per the instrument text, does not materially change the overall thrust or scope of the original directive. (Background)\n\nPrimary source references within this instrument: Applicability; Requirement; Note; Compliance; Background."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a minor amendment to an existing Airworthiness Directive. The document explicitly states that the amendment 'does not constitute a major change in the thrust of the overall AD document.' The scope remains limited to the specific bolt hole inspections and repairs on the specified engine models, exactly as originally intended when the AD was first issued."},"complexity_factors":["Short, single-purpose directive (approximately 200 words)","Only 4 defined/referenced documents (the FAA AD and 4 GE Service Bulletins)","Single applicability criterion (CF6-45/50/-6 series engines)","No nested conditional logic or exceptions — straightforward 'comply with FAA AD' structure","Technical complexity is high for aviation engineers but legislative complexity is low — the document delegates all technical detail to external FAA and GE documents","Cross-references are explicit and limited (FAA AD 94-09-18 plus 4 service bulletins)"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety notice issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific maintenance actions on certain aircraft engines.\n\n**What it does:**\n- Requires inspection and repair of **bolt holes** in specific parts of General Electric CF6 turbine engines — namely the Stage 1 disc rim and Stage 2 disc rim and inner bolt holes in the High Pressure Turbine section.\n- These are critical rotating components that operate under extreme heat and stress.\n\n**Who it affects:**\n- Owners and operators of aircraft powered by **General Electric CF6-45, CF6-50, and CF6-6 series engines**.\n- This includes many older wide-body aircraft like early Boeing 747s, DC-10s, and Airbus A300s.\n\n**Why it matters:**\n- The directive was triggered by a real incident: an **uncontained engine failure** (where engine parts broke through the engine casing) during take-off, caused by a failed high pressure turbine disc.\n- Uncontained failures are extremely dangerous — debris can damage the aircraft structure, fuel tanks, or flight control systems.\n- The AD mandates specific technical procedures originally issued by the US Federal Aviation Administration (FAA) to prevent similar catastrophic failures.\n\n**What must be done:**\n- Maintenance crews must follow the technical instructions in **FAA AD 94-09-18** (September 1994 corrected version).\n- Reference documents include General Electric Service Bulletins 72-1002, 1003, 1057, and 1059.\n- Compliance deadline: **8 December 1994** (revised effective date).\n\nThis amendment (Amendment 1) makes minor updates to two sections but doesn't change the overall safety requirement."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cf6-29-amdt-1-high-pressure-turbine-stage-1-disc-rim-bolt-holes-and-stage-2-disc-rim-and-inner-bo","history":"/api/acts/ad-cf6-29-amdt-1-high-pressure-turbine-stage-1-disc-rim-bolt-holes-and-stage-2-disc-rim-and-inner-bo/history","analysis":"/api/acts/ad-cf6-29-amdt-1-high-pressure-turbine-stage-1-disc-rim-bolt-holes-and-stage-2-disc-rim-and-inner-bo/analysis","conflicts":"/api/acts/ad-cf6-29-amdt-1-high-pressure-turbine-stage-1-disc-rim-bolt-holes-and-stage-2-disc-rim-and-inner-bo/conflicts","importantCases":"/api/acts/ad-cf6-29-amdt-1-high-pressure-turbine-stage-1-disc-rim-bolt-holes-and-stage-2-disc-rim-and-inner-bo/important-cases","documents":"/api/acts/ad-cf6-29-amdt-1-high-pressure-turbine-stage-1-disc-rim-bolt-holes-and-stage-2-disc-rim-and-inner-bo/documents"}}