{"id":"F2006B07462","name":"AD/TPE 331/50 Amdt 1 - First Stage Compressor Impeller","slug":"ad-tpe-331-50-amdt-1-first-stage-compressor-impeller","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49825,"registerId":"commonwealth-F2006B07462-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TPE 331/50 Amdt 1 - First Stage Compressor Impeller","content":"![](image.001.png)\n\n![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive AD/TPE 331/50 and issues the following AD under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.\n\n![](image.001.png)\n\nAlliedSignal (Garrett/AiResearch) Turbine Engines \\- TPE 331 Series\n\nAD/TPE 331/50\n\nAmdt 1\n\n  \nFirst Stage Compressor Impeller 1/2003\n\nApplicability: All TPE331 series engines fitted with part number 896223-1, \\-2, \\-3, \\-7 or part number 3107109-1, \\-2, \\-4 first stage compressor impellers.\n\n| Requirement: | 1.  | Weld repaired impellers:                                                                                                                               |\n| ------------ | --- | ------------------------------------------------------------------------------------------------------------------------------------------------------ |\n|              |     | Remove from service weld repaired first stage compressor impellers detailed by serial number in Honeywell Service Bulletin TPE331-A72-2083 Revision 1. |\n|              | 2.  | Other then weld repaired impellers:                                                                                                                    |\n|              |     | Remove from service first stage compressor impellers in accordance with Honeywell Service Bulletin TPE331-A72-0971 Revision 2.                         |\n| Compliance:  | 1.  | For weld repaired impellers:                                                                                                                           |\n|              |     | a. As detailed in Honeywell Service Bulletin TPE331-A72-2083 Revision 1                                                                                |\n\nwith a revised effective date of 23 January 2003; or\n\nb. As detailed in Honeywell Service Bulletin TPE331-A72-0971 Revision 2 with a revised effective date of 23 January 2003.\n\nWhichever provides for the least number of cycles before removal.\n\n    2. For impellers other than weld repaired impellers:\n\n    As detailed in Honeywell Service Bulletin TPE331-A72-0971 Revision 2 with a revised effective date of 23 January 2003.\n\nThis Amendment becomes effective on 23 January 2003.\n\nBackground: This Directive has been issued to require removal from service of certain first stage compressor impellers. The requireme nt follows advice of an uncontained first stage compressor failure event. Impellers removed from service in accordance with this Directive are to be subjected to an inspection by AlliedSignal and if appropriate, reworking. Serviceable impellers will be returned to service with a nominated cycle life remaining.\n\nAlliedSignal (Garrett/AiResearch) Turbine Engines \\- TPE 331 Series\n\nAD/TPE 331/50 Amdt 1 (continued)\n\nThis Amendment introduces compliance requirements for weld repaired first stage compressor impellers identified by serial number.\n\nThe original issue of this Airworthiness Directive became effective on 9 November 1995.\n\n![Signature of James Coyne Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nJames Coyne\n\nDelegate of the Civil Aviation Safety Authority 28 November 2002\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 18 December 2002.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"The original 1995 directive covered non-weld-repaired impellers only. This 2002 amendment expands scope to include weld-repaired impellers identified by specific serial numbers, following additional safety data. The amendment maintains the original purpose (preventing compressor failures) but broadens the affected population of parts."},"complexity_factors":["Short, single-purpose document (2 pages)","Only 5 defined part numbers in applicability section","Simple binary classification system (weld-repaired vs non-weld-repaired)","Cross-references to 2 external Honeywell Service Bulletins rather than embedding technical details","Clear compliance table with only 2 main pathways","Minimal conditional logic (essentially one IF-THEN-ELSE structure)","No nested exceptions or definitional sections"],"plain_english_summary":"This CASA Airworthiness Directive mandates removal from service of specific first‑stage compressor impellers (part numbers 896223‑1, ‑2, ‑3, ‑7 and 3107109‑1, ‑2, ‑4) fitted to AlliedSignal/Honeywell TPE331 engines due to risk of uncontained engine failure. It affects aircraft owners, operators and maintenance organisations; weld‑repaired impellers listed in Honeywell’s bulletin must be removed immediately, while non‑weld‑repaired impellers are removed per alternate bulletin timelines. Effective 23 January 2003."},"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":"Yes. The amendment revokes the original AD and adds explicit compliance requirements for weld‑repaired first-stage compressor impellers identified by serial number (\"This Amendment introduces compliance requirements for weld repaired first stage compressor impellers identified by serial number\"). It therefore expands/clarifies the AD's scope and imposes serial-number‑specific removals and inspection/rework procedures not specified in the 1995 issue."},"complexity_factors":["Dependence on external technical documents: compliance actions are defined by Honeywell Service Bulletins TPE331-A72-2083 Rev 1 and TPE331-A72-0971 Rev 2 rather than detailed in the AD text (Requirement/Compliance).","Serial-number‑specific applicability for weld‑repaired impellers increases traceability and recordkeeping burdens (Requirement: remove weld repaired impellers detailed by serial number in SB TPE331-A72-2083 Rev 1).","Two-tier treatment: weld‑repaired impellers are treated differently from other impellers, requiring operators to classify parts before applying the correct SB (Requirement).","Decision rule complexity: operators must apply the timing option that 'provides for the least number of cycles before removal', requiring comparison of two SB schedules (Compliance).","Operational and commercial impact: removal, inspection, possible rework by AlliedSignal, and return-to-service with a nominated cycle life impose direct costs and downtime on operators (Background/Requirement).","Regulatory transition: the AD revokes the prior AD/TPE 331/50 and replaces it with amended requirements and a revised effective date (opening paragraph; effective date 23 January 2003), creating a change-management task for operators.","Legal basis and enforcement: issued under subregulation 39.1(1) of CAR 1998, so compliance is mandatory and enforceable (opening paragraph).","Limited technical detail in the AD itself means practical compliance depends on OEM actions and SB revisions, introducing implementation risk if SBs change or are interpreted differently (overall structure)."],"plain_english_summary":"This Airworthiness Directive orders removal from service of certain first-stage compressor impellers (specific part numbers) fitted to TPE331 engines, distinguishing weld‑repaired impellers (to be removed by serial numbers listed in Honeywell SB TPE331-A72-2083 Rev 1) from other impellers (removed per Honeywell SB TPE331-A72-0971 Rev 2). The stated reason is an uncontained first-stage compressor failure; removed impellers must be inspected and, if suitable, reworked by AlliedSignal and returned with a nominated remaining cycle life."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tpe-331-50-amdt-1-first-stage-compressor-impeller","history":"/api/acts/ad-tpe-331-50-amdt-1-first-stage-compressor-impeller/history","analysis":"/api/acts/ad-tpe-331-50-amdt-1-first-stage-compressor-impeller/analysis","conflicts":"/api/acts/ad-tpe-331-50-amdt-1-first-stage-compressor-impeller/conflicts","importantCases":"/api/acts/ad-tpe-331-50-amdt-1-first-stage-compressor-impeller/important-cases","documents":"/api/acts/ad-tpe-331-50-amdt-1-first-stage-compressor-impeller/documents"}}