{"id":"F2006B07443","name":"AD/TPE 331/33 Amdt 3 - Second Stage Turbine Rotor/Seal Interference","slug":"ad-tpe-331-33-amdt-3-second-stage-turbine-rotor-seal-interference","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49750,"registerId":"commonwealth-F2006B07443-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TPE 331/33 Amdt 3 - Second Stage Turbine Rotor/Seal Interference","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)  \nAlliedSignal (Garrett/AiResearch) Turbine Engines \\- TPE 331 Series\n\nAD/TPE 331/33\n\nAmdt 3\n\n  \nSecond Stage Turbine Rotor/Seal Interference 10/87\n\nTX\n\nApplicability: TPE 331-25, \\-43, \\-47, \\-55 and \\-61 series engines as listed in the Requirement Document.\n\nRequirement: 1. Accomplish interim rotational check in accordance with (IAW) GTEC SB TPE 331-A72-0522 Revision 2 Para 2.A.(1).\n\n2. Radiographically inspect the second stage turbine rotor and seal plate assemblies in accordance with GTEC SB TPE 331-A72-0522, Rev 2 dated 1 July 1987.\n\nPara 2. A(2)(3) and (4).\n\nNote: FAA AD 86-08-06 Amdt 39-5275 refers to SB TPE 331-72-0522 Rev 1.\n\nCompliance: For Item 1 above:\n\nWithin 25 operating hours after 3 August 1987 and thereafter at 25 hourly intervals until the initial radiographic inspection IAW Item 2 is completed.\n\nNote: Initial radiographic inspection is completed when the radiographic film has been submitted and acceptable analysis results received from Garrett.\n\nFor Item 2 above:\n\nUnless already accomplished, initially within 100 engine operating hours after 31 August 1986 or prior to achieving 500 engine operating hours since last engine overhaul whichever is the later, and thereafter at intervals not exceeding 300 hours of engine operation.\n\nBackground: This Directive is amended to reflect the manufacturers Alert Status of SB TPE 331- A72-0522 Rev 2 which also includes the TPE 331-61A engine in applicability. SB TPE 331-A72-0522 Rev 2 also makes reference to Alert SB TPE 331-A72-0560 which is the Requirement Document for new AD/TPE 331/35 which is issued concurrent with this Directive.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"The original directive has expanded in scope through this amendment. The 'Background' section explicitly states this amendment adds the TPE 331-61A engine to the applicability, which was not covered in previous versions. The directive also now references a concurrent new directive (AD/TPE 331/35), indicating the safety issue has spawned multiple regulatory responses beyond the original single directive."},"complexity_factors":["Multiple compliance pathways with conditional timing ('whichever is the later' logic)","Cross-references to external manufacturer documents (GTEC Service Bulletins) that are not reproduced in the text","Interdependent compliance items (Item 1 must continue until Item 2 is completed)","Specific engine model variants listed with partial ranges (-25, -43, -47, -55, -61 series)","Reference to concurrent related directive (AD/TPE 331/35) creating inter-document dependencies","Technical aviation terminology requiring specialised knowledge (radiographic inspection, rotational check, overhaul intervals)"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspections on AlliedSignal (Garrett/AiResearch) TPE331 turboprops (including -25, -43, -47, -55, -61 series and newly added 61A) to detect dangerous interference between the second-stage turbine rotor and its seal. Affected owners, operators and maintenance organisations must perform interim rotational spin-checks and periodic radiographic (X-ray) inspections within prescribed timeframes. Compliance is mandatory: the issue can cause catastrophic engine failure and non‑compliance grounds an aircraft from flying in Australian airspace."},"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":5,"scope_assessment":{"changed":true,"description":"The amendment expands applicability to include the TPE331‑61A engine and updates the directive to reflect Service Bulletin TPE 331‑A72‑0522 Revision 2. It also links to an Alert Service Bulletin (TPE 331‑A72‑0560) referenced as the Requirement Document for a concurrent AD, thereby broadening cross‑document dependencies and the set of engines and procedures covered."},"complexity_factors":["Technical inspection requirement: radiographic inspection of second‑stage turbine rotor and seal plate (requires specialised NDT capability).","Multiple, nested compliance intervals (25‑hour interim checks; initial inspection within 100 hours or before 500 hours since overhaul; recurring 300‑hour intervals).","Administrative step tying completion to manufacturer's receipt and acceptance of radiographic film (film submission and analysis required).","Cross-references to specific Service Bulletin revisions (GTEC SB TPE 331‑A72‑0522 Rev 2) and related Alert SBs and FAA ADs, increasing reliance on external documents for implementation.","Applicability spans multiple engine models and was expanded by amendment to include TPE331‑61A, widening operational scope.","Operator burden: tracking engine operating hours, scheduling inspections, potential downtime and coordination with the manufacturer for analysis."],"plain_english_summary":"This airworthiness directive requires operators of certain AlliedSignal TPE331 turboprop engines (‑25, ‑43, ‑47, ‑55 and ‑61) to perform interim rotational checks every 25 operating hours until a radiographic inspection of the second‑stage turbine rotor and seal plate is done, and to carry out radiographic inspections initially within 100 hours (or before 500 hours since overhaul) and then every 300 hours. Operators must submit radiographic film to the manufacturer for analysis. The amendment adds the TPE331‑61A to the engines covered and references updated manufacturer service bulletins."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tpe-331-33-amdt-3-second-stage-turbine-rotor-seal-interference","history":"/api/acts/ad-tpe-331-33-amdt-3-second-stage-turbine-rotor-seal-interference/history","analysis":"/api/acts/ad-tpe-331-33-amdt-3-second-stage-turbine-rotor-seal-interference/analysis","conflicts":"/api/acts/ad-tpe-331-33-amdt-3-second-stage-turbine-rotor-seal-interference/conflicts","importantCases":"/api/acts/ad-tpe-331-33-amdt-3-second-stage-turbine-rotor-seal-interference/important-cases","documents":"/api/acts/ad-tpe-331-33-amdt-3-second-stage-turbine-rotor-seal-interference/documents"}}