{"id":"F2006B06363","name":"AD/PT6A/26 - Power Turbine Containment Ring","slug":"ad-pt6a-26-power-turbine-containment-ring","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47605,"registerId":"commonwealth-F2006B06363-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/PT6A/26 - Power Turbine Containment Ring","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)  \nPratt and Whitney Canada Turbine Engines \\- PT6A Series\n\nAD/PT6A/26 Power Turbine Containment Ring 10/95\n\nApplicability: All PT6A-11, \\-11AG, \\-15AG, \\-110, \\-112, \\-20, \\-20A, \\-20B, \\-21, \\-25, \\-25A, \\-25C, \\-27,\n\n\\-28, -34, -34AG, -34B, -36, -114, -116, -135, -135A engines not incorporating an improved power turbine containment ring fitted in accordance with P & WC Service Bulletin No. 12076 Rev. 3 or SB 1427 as applicable.\n\nRequirement: Modify or replace the power turbine containment ring P/N 3022339 in accordance with P & WC Service Bulletin 12076 Rev 3 or SB 1427 as applicable.\n\nNote: AD/PT6A/17 was in issue to require the installation of a P/N 3022339 power turbine containment ring. AD/PT6A/17 has now been cancelled.\n\nCompliance: Effective 14 September 1995: At next engine shop visit that requires the disassembly of any engine flange, but no later than 30 December 1996.\n\nBackground: This Directive has been issued to require an improvement to the capability of the engine to contain a power turbine blade release. The improvement is by the replacement or modification of the power turbine containment ring. The requirement follows the investigation of a local PT6A-15AG uncontained power turbine blade release event. In that event, a de-coupling and subsequent overspeed of the power turbine resulted in the release of power turbine blades. The P/N 3022339 ring fitted to that PT6A-15AG failed to contain the released power turbine blades.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1220},"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This directive maintains its original targeted scope addressing the specific safety risk of power turbine blade containment failure in PT6A engines. It does not expand beyond the original mechanical safety issue identified following the 1995 incident."},"complexity_factors":["References to external technical documents (P&WC Service Bulletin 12076 Rev 3 and SB 1427) not reproduced in the directive","Specific part numbers (P/N 3022339) and 19 different engine model variants listed in applicability","Conditional applicability based on whether improved ring is already fitted","Compliance deadline tied to maintenance events ('next engine shop visit') rather than calendar date alone","Cancellation of previous directive (AD/PT6A/17) creates historical dependency"],"plain_english_summary":"This mandatory airworthiness directive requires owners/operators of certain Pratt & Whitney Canada PT6A engines to upgrade or replace the power-turbine containment ring per the manufacturer’s service instructions. It targets engines without the improved ring design to prevent uncontained turbine blade failures that can breach the engine casing and threaten aircraft and people on the ground. Compliance is required by 30 December 1996 or at the next major engine service requiring flange disassembly."}},"importantCases":[],"_links":{"self":"/api/acts/ad-pt6a-26-power-turbine-containment-ring","history":"/api/acts/ad-pt6a-26-power-turbine-containment-ring/history","analysis":"/api/acts/ad-pt6a-26-power-turbine-containment-ring/analysis","conflicts":"/api/acts/ad-pt6a-26-power-turbine-containment-ring/conflicts","importantCases":"/api/acts/ad-pt6a-26-power-turbine-containment-ring/important-cases","documents":"/api/acts/ad-pt6a-26-power-turbine-containment-ring/documents"}}