{"id":"F2006B09945","name":"AD/FJ44/1 - High Pressure Turbine Disc","slug":"ad-fj44-1-high-pressure-turbine-disc","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":55202,"registerId":"commonwealth-F2006B09945-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/FJ44/1 - High Pressure Turbine Disc","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)  \nWilliams-Rolls Turbine Engines \\- FJ44 Series\n\nAD/FJ44/1 High Pressure Turbine Disc 5/97\n\nApplicability: FJ44-1A engines as detailed by serial number in Williams-Rolls Service Bulletin (SB) Number FJ44-A72-30 and not incorporating a part number (P/N) 55291 high pressure turbine disc.\n\nRequirement: To prevent a possible high pressure turbine (HPT) disc blade retention post separation and the release of turbine blades event, carry out an initial and repetitive eddy current inspection of the P/N 48629 HPT disc in accordance with the requirements of Williams-Rolls SB No. FJ44-A72-30.\n\nNote 1: FAA Airworthiness Directive 97-01-05 refers.\n\nNote 2: Compliance with Williams-Rolls SB No. FJ44-A72-31 constitutes a terminating action for the requirements of this directive.\n\nCompliance: As detailed in the requirement document with a revised effective date of 24 April 1997.\n\nThis Airworthiness Directive becomes effective on 24 April 1997.\n\nBackground: This directive has been issued to require the inspection of certain HPT discs for evidence of cracking in the blade retention posts. The requirement reflects advice of two in-flight HPT disc blade post separation events involving the Williams-Rolls FJ44 engine. One of the events was uncontained. An investigation of the events revealed in both cases, the HPT blade retention posts separated through cracking caused by material creep/fatigue.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific known failure mode in a specific engine model. It has not expanded beyond its original purpose of preventing HPT disc failures through mandated inspections."},"complexity_factors":["Single, specific mechanical component targeted (HPT disc P/N 48629)","Only one main requirement: perform eddy current inspection per referenced Service Bulletin","Clear applicability criteria based on engine serial numbers and part numbers","Single terminating action clearly identified (compliance with SB FJ44-A72-31)","No nested exceptions or conditional logic — straightforward pass/fail applicability","Short document (approximately 200 words)","Only 3 defined/document references (two Service Bulletins and one FAA AD)"],"plain_english_summary":"This CASA Airworthiness Directive mandates eddy‑current inspection of the High Pressure Turbine (HPT) disc on Williams‑Rolls FJ44‑1A engines (those listed in Service Bulletin FJ44‑A72‑30 that have not been replaced with P/N 55291) after in‑flight failures and an uncontained disc rupture caused by creep/fatigue.  \n\nOperators must perform initial and repetitive inspections per the Service Bulletin; installing the upgraded disc (per SB FJ44‑A72‑31) terminates the inspection requirement. Effective 24 April 1997."},"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":3,"scope_assessment":{"changed":false,"description":"The directive implements inspections targeted at the same HPT disc and affected engines identified in the background; it does not broaden to other engine types or unrelated parts. It preserves the original intent to detect cracking following blade‑post failures while offering a manufacturer SB as a terminating fix (Requirement; Background; Note 2)."},"complexity_factors":["Technical inspection method: requires eddy‑current non‑destructive testing (specialist technicians, equipment, and procedures) (Requirement).","Selective applicability: applies only to FJ44‑1A engines listed by serial number and not fitted with P/N 55291, requiring operators to check parts/serial records (Applicability).","Repetitive schedule: inspections are initial and recurring, creating ongoing operational scheduling and maintenance costs (Requirement).","Terminating action: compliance can be ended by following a separate service bulletin (FJ44‑A72‑31), creating an upgrade/repair decision and capital cost trade‑off (Note 2 / Requirement).","Safety‑critical context: stems from in‑flight uncontained and contained blade post separations, so regulators and operators face high safety and liability stakes (Background).","Inter-agency reference: cross‑referenced FAA AD 97‑01‑05, so international/operators with multi‑jurisdiction fleets must track parallel mandates (Note 1).","Recordkeeping and regulatory compliance: inspectors/operators must document compliance to the Civil Aviation Safety Authority timetable (Compliance)."],"plain_english_summary":"This Airworthiness Directive requires operators of certain Williams‑Rolls FJ44‑1A engines (specified by serial number and lacking the upgraded P/N 55291 HPT disc) to carry out initial and repetitive eddy‑current inspections of the P/N 48629 high‑pressure turbine disc, per Williams‑Rolls Service Bulletin FJ44‑A72‑30. It was issued after in‑flight separations and aims to detect cracking in the blade retention posts; compliance creates inspection costs, potential aircraft downtime, and an alternative terminating action via SB FJ44‑A72‑31."}},"importantCases":[],"_links":{"self":"/api/acts/ad-fj44-1-high-pressure-turbine-disc","history":"/api/acts/ad-fj44-1-high-pressure-turbine-disc/history","analysis":"/api/acts/ad-fj44-1-high-pressure-turbine-disc/analysis","conflicts":"/api/acts/ad-fj44-1-high-pressure-turbine-disc/conflicts","importantCases":"/api/acts/ad-fj44-1-high-pressure-turbine-disc/important-cases","documents":"/api/acts/ad-fj44-1-high-pressure-turbine-disc/documents"}}