{"id":"F2006B02292","name":"AD/AL 250/83 - Third-Stage Turbine Wheels","slug":"ad-al-250-83-third-stage-turbine-wheels","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41522,"registerId":"commonwealth-F2006B02292-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# ![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 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\nAllison Turbine Engines \\- 250 Series","sortOrder":0},{"sectionNumber":"AD/AL 250/83 Third-Stage Turbine Wheels ","sectionType":"part","heading":"AD/AL 250/83 Third-Stage Turbine Wheels 10/2004","content":"# AD/AL 250/83 Third-Stage Turbine Wheels 10/2004\n\nApplicability: Rolls-Royce Corporation (formerly Allison Engine Company), models 250-C28, \\- C28B, and \\-C28C turboshaft engines with third-stage turbine wheels, part number (P/N) 6899383, listed by serial number (SN) in Table 1 of this Directive:","sortOrder":1},{"sectionNumber":"Table 1. - SNs of Affected Third Stage T","sectionType":"part","heading":"Table 1. - SNs of Affected Third Stage Turbine Wheels","content":"## Table 1. \\- SNs of Affected Third Stage Turbine Wheels\n\n| HX91922 | X523242 | X523281 |\n| ------- | ------- | ------- |\n| HX91923 | X523243 | X523283 |\n| HX91925 | X523244 | X523284 |\n| HX91926 | X523246 | X523287 |\n| HX91928 | X523249 | X523288 |\n| HX91929 | X523250 | X523289 |\n| HX91930 | X523251 | X523290 |\n| HX91932 | X523253 | X523291 |\n| HX91934 | X523255 | X523292 |\n| HX91936 | X523257 | X523293 |\n| HX91937 | X523260 | X523294 |\n| HX91939 | X523261 | X523295 |\n| HX91940 | X523262 | X523296 |\n| HX91960 | X523263 | X523297 |\n| HX91962 | X523264 | X523298 |\n| HX91966 | X523265 | X523300 |","sortOrder":2}],"analysis":{"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":4,"scope_assessment":{"changed":false,"description":"Based on the supplied text, the AD’s scope is confined to third‑stage turbine wheels P/N 6899383 listed by serial number in Table 1 and applies to Rolls‑Royce (Allison) 250‑C28 series engines; the instrument as supplied contains no indication that that scope was altered from an earlier or original intent (see Applicability; Table 1; background reference to CASR subregulation 39.1(1))."},"complexity_factors":["Narrow, serial-numbered scope: applicability is limited to wheels P/N 6899383 listed by serial number in Table 1 (Applicability; Table 1).","Regulatory basis and delegated discretion: issued under subregulation 39.1(1) of CASR 1998, giving a CASA delegate authority to require corrective action (background paragraph).","Missing operational detail in supplied text: the specific corrective actions, methods and compliance times are referenced only as being in the requirement and compliance sections but those sections are not included here (background/requirement references).","Technical identification burden: operators must positively identify part numbers and serial numbers on installed turbine wheels, which requires parts traceability and maintenance records (Applicability; Table 1).","Compliance cost and downtime: compliance will likely involve inspections, removals or repairs that impose operational and financial costs on aircraft operators and maintenance organisations (background; Applicability).","Verification and recordkeeping: enforcing the AD requires maintenance organisations and regulators to verify serial numbers and compliance records for the affected parts (Applicability; Table 1).","Concentration of effect: a discrete set of serial-numbered parts concentrates obligations and any replacement/repair demand on owners of those specific parts (Table 1)."],"plain_english_summary":"Mechanically, this Airworthiness Directive orders owners/operators to take corrective action for specific Rolls‑Royce (Allison) 250‑C28, -C28B and -C28C turboshaft engines fitted with third‑stage turbine wheels P/N 6899383 listed by serial number in Table 1. It is issued by a CASA delegate under subregulation 39.1(1) of CASR 1998 to address an identified unsafe condition. Affected aircraft operators and maintenance organisations must follow the AD’s requirement and compliance sections and will bear the operational and financial consequences of inspections, repairs or part removals."},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This appears to be a standard, targeted Airworthiness Directive addressing a specific unsafe condition in specific engine components. The scope is precisely limited to the identified defective parts and has not expanded beyond the original safety purpose."},"complexity_factors":["Highly specific applicability limited to 3 engine models and 48 specific serial numbers","Simple structure: Applicability → Requirement → Compliance (standard AD format)","Minimal cross-referencing — primarily references itself (Table 1) and the enabling regulation (CASR 1998, subreg 39.1(1))","No nested exceptions or conditional logic visible in the excerpt provided","Straightforward command structure: 'The AD requires that the action... be taken'","Single technical part number (P/N 6899383) and clear model identification"],"plain_english_summary":"CASA issues a mandatory Airworthiness Directive requiring inspection or corrective action on specific Rolls‑Royce (Allison) 250‑C28, ‑C28B and ‑C28C engines because of a potentially faulty third‑stage turbine wheel (P/N 6899383).\n\nIt applies only to about 48 wheels identified by serial numbers in Table 1 and mandates replacement or repair to prevent engine failure and possible catastrophic accidents."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-83-third-stage-turbine-wheels","history":"/api/acts/ad-al-250-83-third-stage-turbine-wheels/history","analysis":"/api/acts/ad-al-250-83-third-stage-turbine-wheels/analysis","conflicts":"/api/acts/ad-al-250-83-third-stage-turbine-wheels/conflicts","importantCases":"/api/acts/ad-al-250-83-third-stage-turbine-wheels/important-cases","documents":"/api/acts/ad-al-250-83-third-stage-turbine-wheels/documents"}}