{"id":"F2006B02270","name":"AD/AL 250/59 Amdt 3 - Outer Combustion Case Assemblies P/N 6899237 and 23009569","slug":"ad-al-250-59-amdt-3-outer-combustion-case-assemblies-p-n-6899237-and-23009569","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41500,"registerId":"commonwealth-F2006B02270-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/59 Amdt 3 - Outer Combustion Case Assemblies P/N 6899237 and 23009569","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)  \nAllison Turbine Engines \\- 250 Series\n\nAD/AL 250/59\n\nAmdt 3\n\n  \n\nOuter Combustion Case Assemblies P/N 6899237 and 23009569\n\n  \n3/86\n\nApplicability: All Model 250-C28B, \\-C28C, \\-C30, \\-C30P, \\-C30R and \\-C30S engines which incorporate outer combustion case assemblies P/N 6899237 and 23009569.\n\nRequirement: FAA A.D. 85-25-07 R1 Amdt. 39-5188 as revised by letter dated 22 January 1986.\n\nNote: Allison 250-C28B, \\-C28C; CEB-A-72-2113 Rev 1 and Allison 250-C30, C30P, C30S; CEB-A-72-3115 Rev 1 refer.\n\nIn the absence of an appropriately licensed LAME the daily inspection requirement of this Directive may be carried out, and certified for on the Maintenance Release, by the pilot in command providing he is the holder of a Maintenance Authority (M.A.) relating to the daily inspection requirement of this Directive. A copy of the daily inspection detailed in FAA AD 85-25-07 R1 is to be attached to the Maintenance Release document.\n\nCompliance: In accordance with Requirement Document FAA AD-85-25-07 R1 excepting, paragraph (b) which is changed to read: for Model 250-C30 and -C30S engines installed in Sikorsky Model S-76A Helicopters within the next 150 hours’ time-in- service after 7 February 1986 but not later than 5 March 1986.\n\nBackground: This Amdt. 3 specifies FAA AD 85-25-07 R1 as the requirement document for inspection and subsequent modification and/or replacement of suspect outer combustion case assemblies. FAA AD 85-25-07 is referenced in Amdt. 2 of this directive. R1 to FAA AD 85-25-07 decreases the inspection intervals from “within 50 hours” to “prior to the next flight for some models”.","sortOrder":0}],"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"},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original scope — safety oversight of specific Allison engine combustion cases. While Amendment 3 updates the referenced FAA document and tightens deadlines for specific helicopter models, this represents normal iterative safety regulation rather than scope creep. The directive remains tightly focused on its original purpose: preventing failure of outer combustion case assemblies in the 250-C28 and 250-C30 engine series."},"complexity_factors":["Heavy reliance on external documents: the directive's core requirements are contained entirely in referenced FAA AD 85-25-07 R1, which is not reproduced in the text","Nested conditional logic for compliance deadlines: different rules apply based on engine model (250-C30/C30S) AND aircraft type (Sikorsky S-76A) AND date ranges","Exception to normal maintenance rules: creates a specific exemption allowing pilots (not just Licensed Aircraft Maintenance Engineers) to perform and certify daily inspections, subject to holding a Maintenance Authority","Cross-references to multiple other documents: CEB-A-72-2113 Rev 1 and CEB-A-72-3115 Rev 1 (Allison Commercial Engine Bulletins)","Dual part number applicability (P/N 6899237 and 23009569) requiring verification against physical engine records","Amendment structure requires understanding of previous versions (Amdt 2) to fully grasp the change in inspection intervals"],"plain_english_summary":"This CASA Airworthiness Directive mandates inspection and, if required, replacement of Allison 250 outer combustion case assemblies (P/N 6899237 and 23009569) on specified 250-C28/ C30 series engines, following FAA AD 85-25-07 R1. It affects operators of helicopters and fixed-wing aircraft with those engines; Sikorsky S-76A helicopters face a tightened compliance deadline. Qualified pilots with Maintenance Authority may perform and log daily inspections per the AD."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This Amendment 3 changes the scope of obligations compared with the earlier version by incorporating FAA AD 85‑25‑07 R1, which shortens inspection intervals for some engine models (moving some inspections from “within 50 hours” to in some cases “prior to the next flight”). It also imposes a specific accelerated compliance window for 250‑C30 and C30S engines installed in Sikorsky S‑76A helicopters (150 hours after 7 Feb 1986 or by 5 Mar 1986). Additionally, it formalises a limited exception allowing pilots with a Maintenance Authority to perform and certify the daily inspection when a LAME is not available. These changes tighten and accelerate inspection and remediation responsibilities and add a conditional certification pathway, expanding the practical burden on operators relative to the prior amendment."},"complexity_factors":["Short instrument but depends on external document FAA AD 85‑25‑07 R1 (cross‑reference to another regulatory text)","Single focused technical subject (outer combustion case) but covers multiple engine models (6 models listed)","Two specific part numbers cited (P/N 6899237 and 23009569) — limited scope but precise","Exception/modification to the referenced FAA AD for paragraph (b) applicable only to Model 250‑C30 and C30S in Sikorsky S‑76A introduces a narrow conditional deadline (150 hours or by a calendar date)","Pilot‑inspection exception (conditional on pilot holding a Maintenance Authority) adds a personnel/qualification conditionality","Reference to additional Allison service documents (two CEB references) increases cross‑document navigation","Several discrete compliance obligations: inspect, possibly modify or replace, attach FAA AD inspection detail to Maintenance Release — creates administrative steps"],"plain_english_summary":"**What this instrument does (mechanics)**\n\n- It is an airworthiness directive (safety order) that applies to Allison 250 series turbine engines that use the specific outer combustion case assemblies with part numbers (P/N) 6899237 and 23009569. (See “Applicability”.)\n- It makes compliance with the FAA document “AD 85-25-07 R1 (Amendment 39-5188, revised 22 Jan 1986)” compulsory for the affected Australian operators, except that one paragraph (paragraph (b)) is changed for a narrow set of installations. (See “Requirement” and “Compliance”.)\n- For Model 250-C30 and 250-C30S engines fitted to Sikorsky Model S‑76A helicopters, paragraph (b) is altered so that the required action must be done within the next 150 hours’ time-in-service after 7 February 1986 but in any case not later than 5 March 1986. (See “Compliance”.)\n- The directive allows the daily inspection required by the FAA AD to be carried out and certified on the Maintenance Release by the pilot‑in‑command if: (a) no appropriately licensed LAME (Licensed Aircraft Maintenance Engineer) is available, and (b) that pilot holds a Maintenance Authority (M.A.) covering that daily inspection. A copy of the daily inspection procedure from the FAA AD must be attached to the Maintenance Release. (See paragraph beginning “In the absence of an appropriately licensed LAME”.)\n- The FAA R1 revision referenced shortens inspection intervals for some engine models (moving from “within 50 hours” to in some cases “prior to the next flight”). The Amendment therefore tightens inspection timing for those models. (See “Background”.)\n\n**Who this affects**\n\n- Aircraft operators and owners that operate helicopters or aircraft fitted with Allison 250‑series engines that incorporate P/N 6899237 or 23009569 (listed models: 250‑C28B, ‑C28C, ‑C30, ‑C30P, ‑C30R and ‑C30S). (Applicability.)\n- Maintenance organisations, LAMEs, and pilots who hold a Maintenance Authority and may be asked to perform and certify daily inspections when no LAME is available. (See the pilot‑inspection exception.)\n- Parts suppliers and overhaul facilities that service or replace the specified outer combustion case assemblies.\n\n**Why it matters (stated purpose and practical effects)**\n\n- The stated purpose (from the instrument’s Background) is to require inspection and, if necessary, modification or replacement of suspect outer combustion case assemblies to maintain safe engine operation. The R1 revision reduces inspection intervals to detect potential failures sooner. (Background; Requirement.)\n\n- Practical effects and immediate requirements:\n  - Operators must follow FAA AD 85‑25‑07 R1 as the required procedure document, including the tighter inspection timings where specified. (Requirement.)\n  - For affected S‑76A installations, a hard compliance window is imposed (150 flight hours after 7 Feb 1986 or by 5 Mar 1986). (Compliance.)\n  - If defects are found, engines or the combustion case assemblies must be modified or replaced per the FAA AD.\n  - Where a LAME is unavailable, a pilot who holds an appropriate Maintenance Authority may perform and sign off the daily inspection, but must attach the FAA AD’s inspection detail to the Maintenance Release.\n\n**Who pays, who decides, and how behaviour changes**\n\n- Who pays: aircraft operators and owners bear the costs — labour, inspections, any modifications, parts and possible aircraft downtime. Maintenance organisations will also expend resources and may see increased demand for parts or shop time.\n- Who decides: the Civil Aviation Safety Authority enforces compliance by incorporating the FAA AD into the Australian directive; operators decide how to schedule inspections and whether to use LAMEs, maintenance‑qualified pilots, or maintenance organisations to meet the directive.\n- Behaviour changes: operators will tighten inspection scheduling, may accelerate replacement/modification of suspect parts, and where licensed maintenance personnel are unavailable may rely on pilots with Maintenance Authority to do daily inspections and sign the Maintenance Release.\n\n**Costs, incentives, trade‑offs and risks**\n\n- Direct costs: increased inspection frequency (in some cases moving to inspection before the next flight) raises recurring labour cost and may increase parts consumption and shop hours. Urgent compliance deadlines (specific to some S‑76A installations) can cause short‑term spikes in maintenance demand and aircraft downtime.\n- Incentives and substitution: operators may shift inspections to in‑house maintenance teams, qualified pilots (where permitted), or outsource to third‑party MROs (maintenance, repair and overhaul) depending on relative cost and availability. That can concentrate demand on certain service providers and create availability bottlenecks for parts and workshop capacity.\n- Compliance burden and administrative cost: must attach FAA AD inspection details to Maintenance Release; must track specific compliance windows and record inspections/replacements. This increases record‑keeping and oversight costs.\n- Implementation risk: pilot‑performed inspections (allowed only if the pilot holds an M.A.) may lead to uneven inspection quality compared with a LAME, depending on the pilot’s maintenance experience and oversight. Short deadlines increase the risk of non‑compliance or rushed inspections.\n- Opportunity cost: time and funds spent meeting these inspections and modifying/replacing parts cannot be used for other maintenance or operational priorities.\n\n**Concentrated benefits and diffuse costs**\n\n- The safety benefit (reduced risk of engine failure) is concentrated on individual flights and the immediate aircraft occupants and operator; the costs (inspection, modification, downtime) are borne by the operator and maintenance supply chain. The directive tightens inspection timing (Background), increasing operator cost to achieve the stated safety objective.\n\n**Implementation notes / cross‑references**\n\n- The directive cross‑references FAA AD 85‑25‑07 R1 (Amendment 39‑5188) and specific Allison engine service documents cited in the Note. Operators must consult those documents for the exact inspection and modification procedures. (Requirement; Note.)"}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-59-amdt-3-outer-combustion-case-assemblies-p-n-6899237-and-23009569","history":"/api/acts/ad-al-250-59-amdt-3-outer-combustion-case-assemblies-p-n-6899237-and-23009569/history","analysis":"/api/acts/ad-al-250-59-amdt-3-outer-combustion-case-assemblies-p-n-6899237-and-23009569/analysis","conflicts":"/api/acts/ad-al-250-59-amdt-3-outer-combustion-case-assemblies-p-n-6899237-and-23009569/conflicts","importantCases":"/api/acts/ad-al-250-59-amdt-3-outer-combustion-case-assemblies-p-n-6899237-and-23009569/important-cases","documents":"/api/acts/ad-al-250-59-amdt-3-outer-combustion-case-assemblies-p-n-6899237-and-23009569/documents"}}